Add executor with high and low priority queues.

Add a setting to disable Tor when running on battery

Closes #978

See merge request briar/briar!1032

bramble-android/src/main/java/org/briarproject/bramble/battery/AndroidBatteryManager.java

@@ -19,9 +19,7 @@ import javax.inject.Inject;
 import static android.content.Intent.ACTION_BATTERY_CHANGED;
 import static android.content.Intent.ACTION_POWER_CONNECTED;
 import static android.content.Intent.ACTION_POWER_DISCONNECTED;
-import static android.os.BatteryManager.BATTERY_STATUS_CHARGING;
-import static android.os.BatteryManager.BATTERY_STATUS_FULL;
-import static android.os.BatteryManager.EXTRA_STATUS;
+import static android.os.BatteryManager.EXTRA_PLUGGED;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Logger.getLogger;
 
@@ -48,9 +46,8 @@ class AndroidBatteryManager implements BatteryManager, Service {
 		IntentFilter filter = new IntentFilter(ACTION_BATTERY_CHANGED);
 		Intent i = appContext.registerReceiver(null, filter);
 		if (i == null) return false;
-		int status = i.getIntExtra(EXTRA_STATUS, -1);
-		return status == BATTERY_STATUS_CHARGING ||
-				status == BATTERY_STATUS_FULL;
+		int status = i.getIntExtra(EXTRA_PLUGGED, 0);
+		return status != 0;
 	}
 
 	@Override

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/TorConstants.java

@@ -16,6 +16,7 @@ public interface TorConstants {
 	String PREF_TOR_NETWORK = "network2";
 	String PREF_TOR_PORT = "port";
 	String PREF_TOR_MOBILE = "useMobileData";
+	String PREF_TOR_ONLY_WHEN_CHARGING = "onlyWhenCharging";
 
 	int PREF_TOR_NETWORK_AUTOMATIC = 0;
 	int PREF_TOR_NETWORK_WITHOUT_BRIDGES = 1;

bramble-core/src/main/java/org/briarproject/bramble/PriorityExecutor.java

@@ -0,0 +1,67 @@
+package org.briarproject.bramble;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.util.LinkedList;
+import java.util.Queue;
+import java.util.concurrent.Executor;
+
+import javax.annotation.concurrent.GuardedBy;
+
+@NotNullByDefault
+public class PriorityExecutor {
+
+	private final Object lock = new Object();
+	private final Executor delegate, high, low;
+	@GuardedBy("lock")
+	private final Queue<Runnable> highQueue = new LinkedList<>();
+	@GuardedBy("lock")
+	private final Queue<Runnable> lowQueue = new LinkedList<>();
+
+	@GuardedBy("lock")
+	private boolean isTaskRunning = false;
+
+	public PriorityExecutor(Executor delegate) {
+		this.delegate = delegate;
+		high = r -> submit(r, true);
+		low = r -> submit(r, false);
+	}
+
+	public Executor getHighPriorityExecutor() {
+		return high;
+	}
+
+	public Executor getLowPriorityExecutor() {
+		return low;
+	}
+
+	private void submit(Runnable r, boolean isHighPriority) {
+		Runnable wrapped = () -> {
+			try {
+				r.run();
+			} finally {
+				scheduleNext();
+			}
+		};
+		synchronized (lock) {
+			if (!isTaskRunning && highQueue.isEmpty() &&
+					(isHighPriority || lowQueue.isEmpty())) {
+				isTaskRunning = true;
+				delegate.execute(wrapped);
+			} else if (isHighPriority) {
+				highQueue.add(wrapped);
+			} else {
+				lowQueue.add(wrapped);
+			}
+		}
+	}
+
+	private void scheduleNext() {
+		synchronized (lock) {
+			Runnable next = highQueue.poll();
+			if (next == null) next = lowQueue.poll();
+			if (next == null) isTaskRunning = false;
+			else delegate.execute(next);
+		}
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/plugin/tor/TorPlugin.java

@@ -69,6 +69,7 @@ import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_NETWORK;
 import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_NETWORK_AUTOMATIC;
 import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_NETWORK_NEVER;
 import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_NETWORK_WITH_BRIDGES;
+import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_ONLY_WHEN_CHARGING;
 import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_PORT;
 import static org.briarproject.bramble.api.plugin.TorConstants.PROP_ONION_V2;
 import static org.briarproject.bramble.api.plugin.TorConstants.PROP_ONION_V3;
@@ -648,8 +649,10 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			if (s.getNamespace().equals(ID.getString())) {
 				LOG.info("Tor settings updated");
 				settings = s.getSettings();
-				// Works around a bug introduced in Tor 0.3.4.8. Could be
-				// replaced with callback.transportDisabled() when fixed.
+				// Works around a bug introduced in Tor 0.3.4.8.
+				// https://trac.torproject.org/projects/tor/ticket/28027
+				// Could be replaced with callback.transportDisabled()
+				// when fixed.
 				disableNetwork();
 				updateConnectionStatus(networkManager.getNetworkStatus(),
 						batteryManager.isCharging());
@@ -685,6 +688,8 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			int network = settings.getInt(PREF_TOR_NETWORK,
 					PREF_TOR_NETWORK_AUTOMATIC);
 			boolean useMobile = settings.getBoolean(PREF_TOR_MOBILE, true);
+			boolean onlyWhenCharging =
+					settings.getBoolean(PREF_TOR_ONLY_WHEN_CHARGING, false);
 			boolean bridgesWork = circumventionProvider.doBridgesWork(country);
 			boolean automatic = network == PREF_TOR_NETWORK_AUTOMATIC;
 
@@ -699,9 +704,12 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 				if (!online) {
 					LOG.info("Disabling network, device is offline");
 					enableNetwork(false);
+				} else if (!charging && onlyWhenCharging) {
+					LOG.info("Disabling network, device is on battery");
+					enableNetwork(false);
 				} else if (network == PREF_TOR_NETWORK_NEVER ||
 						(!useMobile && !wifi)) {
-					LOG.info("Disabling network due to setting");
+					LOG.info("Disabling network, device is using mobile data");
 					enableNetwork(false);
 				} else if (automatic && blocked && !bridgesWork) {
 					LOG.info("Disabling network, country is blocked");

bramble-core/src/test/java/org/briarproject/bramble/PriorityExecutorTest.java

@@ -0,0 +1,86 @@
+package org.briarproject.bramble;
+
+import org.briarproject.bramble.test.BrambleTestCase;
+import org.junit.Test;
+
+import java.util.List;
+import java.util.Vector;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.Executor;
+
+import static java.util.Arrays.asList;
+import static java.util.concurrent.Executors.newSingleThreadExecutor;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
+
+public class PriorityExecutorTest extends BrambleTestCase {
+
+	@Test
+	public void testHighPriorityTasksAreDelegatedInOrderOfSubmission()
+			throws Exception {
+		Executor delegate = newSingleThreadExecutor();
+		PriorityExecutor priority = new PriorityExecutor(delegate);
+		Executor high = priority.getHighPriorityExecutor();
+		testTasksAreDelegatedInOrderOfSubmission(high);
+	}
+
+	@Test
+	public void testLowPriorityTasksAreDelegatedInOrderOfSubmission()
+			throws Exception {
+		Executor delegate = newSingleThreadExecutor();
+		PriorityExecutor priority = new PriorityExecutor(delegate);
+		Executor low = priority.getLowPriorityExecutor();
+		testTasksAreDelegatedInOrderOfSubmission(low);
+	}
+
+	@Test
+	public void testHighPriorityTasksAreRunFirst() throws Exception {
+		Executor delegate = newSingleThreadExecutor();
+		PriorityExecutor priority = new PriorityExecutor(delegate);
+		Executor high = priority.getHighPriorityExecutor();
+		Executor low = priority.getLowPriorityExecutor();
+		// Submit a task that will block, causing other tasks to be queued
+		CountDownLatch cork = new CountDownLatch(1);
+		low.execute(() -> {
+			try {
+				cork.await();
+			} catch (InterruptedException e) {
+				fail();
+			}
+		});
+		// Submit alternating tasks to the high and low priority executors
+		List<Integer> results = new Vector<>();
+		CountDownLatch tasksFinished = new CountDownLatch(10);
+		for (int i = 0; i < 10; i++) {
+			int result = i;
+			Runnable task = () -> {
+				results.add(result);
+				tasksFinished.countDown();
+			};
+			if (i % 2 == 0) high.execute(task);
+			else low.execute(task);
+		}
+		// Release the cork and wait for all tasks to finish
+		cork.countDown();
+		tasksFinished.await();
+		// The high-priority tasks should have run before the low-priority tasks
+		assertEquals(asList(0, 2, 4, 6, 8, 1, 3, 5, 7, 9), results);
+	}
+
+	private void testTasksAreDelegatedInOrderOfSubmission(Executor e)
+			throws Exception {
+		List<Integer> results = new Vector<>();
+		CountDownLatch tasksFinished = new CountDownLatch(10);
+		for (int i = 0; i < 10; i++) {
+			int result = i;
+			e.execute(() -> {
+				results.add(result);
+				tasksFinished.countDown();
+			});
+		}
+		// Wait for all the tasks to finish
+		tasksFinished.await();
+		// The tasks should have run in the order they were submitted
+		assertEquals(asList(0, 1, 2, 3, 4, 5, 6, 7, 8, 9), results);
+	}
+}

briar-android/build.gradle

@@ -105,7 +105,6 @@ dependencies {
 	implementation "com.android.support:cardview-v7:$supportVersion"
 	implementation "com.android.support:support-annotations:$supportVersion"
 	implementation "com.android.support:exifinterface:$supportVersion"
-	implementation "com.android.support:palette-v7:$supportVersion"
 	implementation 'com.android.support.constraint:constraint-layout:1.1.3'
 	implementation "android.arch.lifecycle:extensions:1.1.1"
 
@@ -117,7 +116,7 @@ dependencies {
 	implementation 'info.guardianproject.trustedintents:trustedintents:0.2'
 	implementation 'de.hdodenhof:circleimageview:2.2.0'
 	implementation 'com.google.zxing:core:3.3.3'
-	implementation 'uk.co.samuelwall:material-tap-target-prompt:2.12.4'
+	implementation 'uk.co.samuelwall:material-tap-target-prompt:2.14.0'
 	implementation 'com.vanniktech:emoji-google:0.5.1'
 	def glideVersion = '4.8.0'
 	implementation("com.github.bumptech.glide:glide:$glideVersion") {
@@ -135,7 +134,7 @@ dependencies {
 	testImplementation project(path: ':bramble-core', configuration: 'testOutput')
 	testImplementation 'org.robolectric:robolectric:4.0.1'
 	testImplementation 'org.robolectric:shadows-support-v4:3.3.2'
-	testImplementation 'org.mockito:mockito-core:2.13.0'
+	testImplementation 'org.mockito:mockito-core:2.19.0'
 	testImplementation 'junit:junit:4.12'
 	testImplementation "org.jmock:jmock:2.8.2"
 	testImplementation "org.jmock:jmock-junit4:2.8.2"

briar-android/src/androidTestOfficial/java/org/briarproject/briar/android/conversation/AttachmentControllerIntegrationTest.java

@@ -0,0 +1,279 @@
+package org.briarproject.briar.android.conversation;
+
+import android.content.res.AssetManager;
+import android.support.test.InstrumentationRegistry;
+import android.support.test.runner.AndroidJUnit4;
+
+import org.briarproject.bramble.api.UniqueId;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.briar.api.messaging.Attachment;
+import org.briarproject.briar.api.messaging.AttachmentHeader;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.URL;
+import java.util.Random;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+@RunWith(AndroidJUnit4.class)
+public class AttachmentControllerIntegrationTest {
+
+	private static final String smallKitten =
+			"https://upload.wikimedia.org/wikipedia/commons/thumb/0/06/Kitten_in_Rizal_Park%2C_Manila.jpg/160px-Kitten_in_Rizal_Park%2C_Manila.jpg";
+	private static final String originalKitten =
+			"https://upload.wikimedia.org/wikipedia/commons/0/06/Kitten_in_Rizal_Park%2C_Manila.jpg";
+	private static final String pngKitten =
+			"https://upload.wikimedia.org/wikipedia/commons/c/c8/Young_cat.png";
+	private static final String uberGif =
+			"https://raw.githubusercontent.com/fuzzdb-project/fuzzdb/master/attack/file-upload/malicious-images/uber.gif";
+	private static final String lottaPixel =
+			"https://raw.githubusercontent.com/fuzzdb-project/fuzzdb/master/attack/file-upload/malicious-images/lottapixel.jpg";
+	private static final String imageIoCrash =
+			"https://www.landaire.net/img/crasher.png";
+	private static final String gimpCrash =
+			"https://gitlab.gnome.org/GNOME/gimp/uploads/75f5b7ed3b09b3f1c13f1f65bffe784f/31153c919d3aa634e8e6cff82219fe7352dd8a37.png";
+	private static final String optiPngAfl =
+			"https://sourceforge.net/p/optipng/bugs/64/attachment/test.gif";
+	private static final String librawError =
+			"https://www.libraw.org/sites/libraw.org/files/P1010671.JPG";
+
+	private final AttachmentDimensions dimensions = new AttachmentDimensions(
+			100, 50, 200, 75, 300
+	);
+	private final MessageId msgId = new MessageId(getRandomId());
+
+	private final AttachmentController controller =
+			new AttachmentController(null, dimensions);
+
+	@Test
+	public void testSmallJpegImage() throws Exception {
+		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
+		InputStream is = getUrlInputStream(smallKitten);
+		Attachment a = new Attachment(is);
+		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		assertEquals(msgId, item.getMessageId());
+		assertEquals(160, item.getWidth());
+		assertEquals(240, item.getHeight());
+		assertEquals(160, item.getThumbnailWidth());
+		assertEquals(240, item.getThumbnailHeight());
+		assertEquals("image/jpeg", item.getMimeType());
+		assertEquals("jpg", item.getExtension());
+		assertFalse(item.hasError());
+	}
+
+	@Test
+	public void testBigJpegImage() throws Exception {
+		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
+		InputStream is = getUrlInputStream(originalKitten);
+		Attachment a = new Attachment(is);
+		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		assertEquals(msgId, item.getMessageId());
+		assertEquals(1728, item.getWidth());
+		assertEquals(2592, item.getHeight());
+		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
+		assertEquals(dimensions.maxHeight, item.getThumbnailHeight());
+		assertEquals("image/jpeg", item.getMimeType());
+		assertEquals("jpg", item.getExtension());
+		assertFalse(item.hasError());
+	}
+
+	@Test
+	public void testSmallPngImage() throws Exception {
+		AttachmentHeader h = new AttachmentHeader(msgId, "image/png");
+		InputStream is = getUrlInputStream(pngKitten);
+		Attachment a = new Attachment(is);
+		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		assertEquals(msgId, item.getMessageId());
+		assertEquals(737, item.getWidth());
+		assertEquals(510, item.getHeight());
+		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
+		assertEquals(138, item.getThumbnailHeight());
+		assertEquals("image/png", item.getMimeType());
+		assertEquals("png", item.getExtension());
+		assertFalse(item.hasError());
+	}
+
+	@Test
+	public void testUberGif() throws Exception {
+		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
+		InputStream is = getUrlInputStream(uberGif);
+		Attachment a = new Attachment(is);
+		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		assertEquals(1, item.getWidth());
+		assertEquals(1, item.getHeight());
+		assertEquals(dimensions.minHeight, item.getThumbnailWidth());
+		assertEquals(dimensions.minHeight, item.getThumbnailHeight());
+		assertEquals("image/gif", item.getMimeType());
+		assertEquals("gif", item.getExtension());
+		assertFalse(item.hasError());
+	}
+
+	@Test
+	public void testLottaPixels() throws Exception {
+		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
+		InputStream is = getUrlInputStream(lottaPixel);
+		Attachment a = new Attachment(is);
+		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		assertEquals(64250, item.getWidth());
+		assertEquals(64250, item.getHeight());
+		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
+		assertEquals(dimensions.maxWidth, item.getThumbnailHeight());
+		assertEquals("image/jpeg", item.getMimeType());
+		assertEquals("jpg", item.getExtension());
+		assertFalse(item.hasError());
+	}
+
+	@Test
+	public void testImageIoCrash() throws Exception {
+		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
+		InputStream is = getUrlInputStream(imageIoCrash);
+		Attachment a = new Attachment(is);
+		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		assertEquals(1184, item.getWidth());
+		assertEquals(448, item.getHeight());
+		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
+		assertEquals(dimensions.minHeight, item.getThumbnailHeight());
+		assertEquals("image/png", item.getMimeType());
+		assertEquals("png", item.getExtension());
+		assertFalse(item.hasError());
+	}
+
+	@Test
+	public void testGimpCrash() throws Exception {
+		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
+		InputStream is = getUrlInputStream(gimpCrash);
+		Attachment a = new Attachment(is);
+		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		assertEquals(1, item.getWidth());
+		assertEquals(1, item.getHeight());
+		assertEquals(dimensions.minHeight, item.getThumbnailWidth());
+		assertEquals(dimensions.minHeight, item.getThumbnailHeight());
+		assertEquals("image/gif", item.getMimeType());
+		assertEquals("gif", item.getExtension());
+		assertFalse(item.hasError());
+	}
+
+	@Test
+	public void testOptiPngAfl() throws Exception {
+		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
+		InputStream is = getUrlInputStream(optiPngAfl);
+		Attachment a = new Attachment(is);
+		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		assertEquals(32, item.getWidth());
+		assertEquals(32, item.getHeight());
+		assertEquals(dimensions.minHeight, item.getThumbnailWidth());
+		assertEquals(dimensions.minHeight, item.getThumbnailHeight());
+		assertEquals("image/gif", item.getMimeType());
+		assertEquals("gif", item.getExtension());
+		assertFalse(item.hasError());
+	}
+
+	@Test
+	public void testLibrawError() throws Exception {
+		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
+		InputStream is = getUrlInputStream(librawError);
+		Attachment a = new Attachment(is);
+		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		assertTrue(item.hasError());
+	}
+
+	@Test
+	public void testSmallAnimatedGifMaxDimensions() throws Exception {
+		AttachmentHeader h = new AttachmentHeader(msgId, "image/gif");
+		InputStream is = getAssetInputStream("animated.gif");
+		Attachment a = new Attachment(is);
+		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		assertEquals(65535, item.getWidth());
+		assertEquals(65535, item.getHeight());
+		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
+		assertEquals(dimensions.maxWidth, item.getThumbnailHeight());
+		assertEquals("image/gif", item.getMimeType());
+		assertEquals("gif", item.getExtension());
+		assertFalse(item.hasError());
+	}
+
+	@Test
+	public void testSmallAnimatedGifHugeDimensions() throws Exception {
+		AttachmentHeader h = new AttachmentHeader(msgId, "image/gif");
+		InputStream is = getAssetInputStream("animated2.gif");
+		Attachment a = new Attachment(is);
+		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		assertEquals(10000, item.getWidth());
+		assertEquals(10000, item.getHeight());
+		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
+		assertEquals(dimensions.maxWidth, item.getThumbnailHeight());
+		assertEquals("image/gif", item.getMimeType());
+		assertEquals("gif", item.getExtension());
+		assertFalse(item.hasError());
+	}
+
+	@Test
+	public void testSmallGifLargeDimensions() throws Exception {
+		AttachmentHeader h = new AttachmentHeader(msgId, "image/gif");
+		InputStream is = getAssetInputStream("error_large.gif");
+		Attachment a = new Attachment(is);
+		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		assertEquals(16384, item.getWidth());
+		assertEquals(16384, item.getHeight());
+		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
+		assertEquals(dimensions.maxWidth, item.getThumbnailHeight());
+		assertEquals("image/gif", item.getMimeType());
+		assertEquals("gif", item.getExtension());
+		assertFalse(item.hasError());
+	}
+
+	@Test
+	public void testHighError() throws Exception {
+		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
+		InputStream is = getAssetInputStream("error_high.jpg");
+		Attachment a = new Attachment(is);
+		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		assertEquals(1, item.getWidth());
+		assertEquals(10000, item.getHeight());
+		assertEquals(dimensions.minWidth, item.getThumbnailWidth());
+		assertEquals(dimensions.maxHeight, item.getThumbnailHeight());
+		assertEquals("image/jpeg", item.getMimeType());
+		assertEquals("jpg", item.getExtension());
+		assertFalse(item.hasError());
+	}
+
+	@Test
+	public void testWideError() throws Exception {
+		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
+		InputStream is = getAssetInputStream("error_wide.jpg");
+		Attachment a = new Attachment(is);
+		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		assertEquals(1920, item.getWidth());
+		assertEquals(1, item.getHeight());
+		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
+		assertEquals(dimensions.minHeight, item.getThumbnailHeight());
+		assertEquals("image/jpeg", item.getMimeType());
+		assertEquals("jpg", item.getExtension());
+		assertFalse(item.hasError());
+	}
+
+	private InputStream getUrlInputStream(String url) throws IOException {
+		return new URL(url).openStream();
+	}
+
+	private InputStream getAssetInputStream(String name) throws IOException {
+		AssetManager assets = InstrumentationRegistry.getContext().getAssets();
+		return assets.open(name);
+	}
+
+	public static byte[] getRandomBytes(int length) {
+		byte[] b = new byte[length];
+		new Random().nextBytes(b);
+		return b;
+	}
+
+	public static byte[] getRandomId() {
+		return getRandomBytes(UniqueId.LENGTH);
+	}
+
+}

briar-android/src/androidTestOfficial/java/org/briarproject/briar/android/conversation/ConversationActivityNotSignedInTest.java

@@ -0,0 +1,38 @@
+package org.briarproject.briar.android.conversation;
+
+import android.content.Context;
+import android.content.Intent;
+import android.support.test.rule.ActivityTestRule;
+import android.support.test.runner.AndroidJUnit4;
+
+import org.briarproject.briar.R;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import static android.support.test.InstrumentationRegistry.getInstrumentation;
+import static android.support.test.espresso.Espresso.onView;
+import static android.support.test.espresso.matcher.ViewMatchers.isDisplayed;
+import static android.support.test.espresso.matcher.ViewMatchers.withText;
+import static org.briarproject.briar.android.ViewActions.waitUntilMatches;
+import static org.briarproject.briar.android.conversation.ConversationActivity.CONTACT_ID;
+
+@RunWith(AndroidJUnit4.class)
+public class ConversationActivityNotSignedInTest {
+
+	@Rule
+	public ActivityTestRule<ConversationActivity> testRule =
+			new ActivityTestRule<>(ConversationActivity.class, false, false);
+
+	@Test
+	public void openWithoutSignedIn() {
+		Context targetContext = getInstrumentation().getTargetContext();
+		Intent intent = new Intent(targetContext, ConversationActivity.class);
+		intent.putExtra(CONTACT_ID, 1);
+		testRule.launchActivity(intent);
+
+		onView(withText(R.string.sign_in_button))
+				.perform(waitUntilMatches(isDisplayed()));
+	}
+
+}

briar-android/src/main/AndroidManifest.xml

@@ -1,6 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest
 	package="org.briarproject.briar"
+	xmlns:tools="http://schemas.android.com/tools"
 	xmlns:android="http://schemas.android.com/apk/res/android">
 
 	<uses-feature android:name="android.hardware.bluetooth" android:required="false"/>
@@ -29,7 +30,8 @@
 		android:label="@string/app_name"
 		android:logo="@mipmap/ic_launcher_round"
 		android:supportsRtl="true"
-		android:theme="@style/BriarTheme">
+		android:theme="@style/BriarTheme"
+		tools:ignore="GoogleAppIndexingWarning">
 
 		<receiver
 			android:name="org.briarproject.briar.android.login.SignInReminderReceiver"
@@ -117,7 +119,7 @@
 		<activity
 			android:name=".android.conversation.ImageActivity"
 			android:parentActivityName="org.briarproject.briar.android.conversation.ConversationActivity"
-			android:theme="@style/BriarTheme.Transparent.NoActionBar">
+			android:theme="@style/BriarTheme.ActionBarOverlay">
 			<meta-data
 				android:name="android.support.PARENT_ACTIVITY"
 				android:value="org.briarproject.briar.android.conversation.ConversationActivity"/>
@@ -155,7 +157,7 @@
 				android:value="org.briarproject.briar.android.navdrawer.NavDrawerActivity"/>
 		</activity>
 
-			<activity
+		<activity
 			android:name="org.briarproject.briar.android.privategroup.memberlist.GroupMemberListActivity"
 			android:label="@string/groups_member_list"
 			android:parentActivityName="org.briarproject.briar.android.privategroup.conversation.GroupActivity"
@@ -398,7 +400,7 @@
 		<activity
 			android:name="org.briarproject.briar.android.panic.PanicResponderActivity"
 			android:noHistory="true"
-			android:theme="@style/Theme.AppCompat.NoActionBar">
+			android:theme="@style/TranslucentTheme">
 			<!-- this can never have launchMode singleTask or singleInstance! -->
 			<intent-filter>
 				<action android:name="info.guardianproject.panic.action.TRIGGER"/>
@@ -408,12 +410,12 @@
 
 		<activity
 			android:name="org.briarproject.briar.android.logout.ExitActivity"
-			android:theme="@style/Theme.AppCompat.NoActionBar">
+			android:theme="@android:style/Theme.NoDisplay">
 		</activity>
 
 		<activity
 			android:name=".android.logout.HideUiActivity"
-			android:theme="@style/Theme.AppCompat.NoActionBar">
+			android:theme="@android:style/Theme.NoDisplay">
 		</activity>
 
 		<activity

briar-android/src/main/java/org/briarproject/briar/android/BackgroundMonitor.java

@@ -0,0 +1,54 @@
+package org.briarproject.briar.android;
+
+import android.app.Activity;
+import android.app.Application.ActivityLifecycleCallbacks;
+import android.os.Bundle;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.util.concurrent.atomic.AtomicInteger;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.ThreadSafe;
+
+@ThreadSafe
+@NotNullByDefault
+class BackgroundMonitor implements ActivityLifecycleCallbacks {
+
+	private final AtomicInteger foregroundActivities = new AtomicInteger(0);
+
+	boolean isRunningInBackground() {
+		return foregroundActivities.get() == 0;
+	}
+
+	@Override
+	public void onActivityCreated(Activity a, @Nullable Bundle state) {
+	}
+
+	@Override
+	public void onActivityStarted(Activity a) {
+		foregroundActivities.incrementAndGet();
+	}
+
+	@Override
+	public void onActivityResumed(Activity a) {
+	}
+
+	@Override
+	public void onActivityPaused(Activity a) {
+	}
+
+	@Override
+	public void onActivityStopped(Activity a) {
+		foregroundActivities.decrementAndGet();
+	}
+
+	@Override
+	public void onActivitySaveInstanceState(Activity a,
+			@Nullable Bundle outState) {
+	}
+
+	@Override
+	public void onActivityDestroyed(Activity a) {
+	}
+}

briar-android/src/main/java/org/briarproject/briar/android/BriarApplication.java

@@ -16,4 +16,6 @@ public interface BriarApplication {
 	AndroidComponent getApplicationComponent();
 
 	SharedPreferences getDefaultSharedPreferences();
+
+	boolean isRunningInBackground();
 }

briar-android/src/main/java/org/briarproject/briar/android/BriarApplicationImpl.java

@@ -1,5 +1,7 @@
 package org.briarproject.briar.android;
 
+import android.app.ActivityManager;
+import android.app.ActivityManager.RunningAppProcessInfo;
 import android.app.Application;
 import android.content.Context;
 import android.content.SharedPreferences;
@@ -30,6 +32,8 @@ import java.util.logging.Handler;
 import java.util.logging.LogRecord;
 import java.util.logging.Logger;
 
+import static android.app.ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND;
+import static android.os.Build.VERSION.SDK_INT;
 import static java.util.logging.Level.FINE;
 import static java.util.logging.Level.INFO;
 import static org.acra.ReportField.ANDROID_VERSION;
@@ -79,6 +83,7 @@ public class BriarApplicationImpl extends Application
 			Logger.getLogger(BriarApplicationImpl.class.getName());
 
 	private final CachingLogHandler logHandler = new CachingLogHandler();
+	private final BackgroundMonitor backgroundMonitor = new BackgroundMonitor();
 
 	private AndroidComponent applicationComponent;
 	private volatile SharedPreferences prefs;
@@ -115,6 +120,9 @@ public class BriarApplicationImpl extends Application
 
 		applicationComponent = createApplicationComponent();
 		EmojiManager.install(new GoogleEmojiProvider());
+
+		if (SDK_INT < 16)
+			registerActivityLifecycleCallbacks(backgroundMonitor);
 	}
 
 	protected AndroidComponent createApplicationComponent() {
@@ -173,4 +181,15 @@ public class BriarApplicationImpl extends Application
 	public SharedPreferences getDefaultSharedPreferences() {
 		return prefs;
 	}
+
+	@Override
+	public boolean isRunningInBackground() {
+		if (SDK_INT >= 16) {
+			RunningAppProcessInfo info = new RunningAppProcessInfo();
+			ActivityManager.getMyMemoryState(info);
+			return (info.importance != IMPORTANCE_FOREGROUND);
+		} else {
+			return backgroundMonitor.isRunningInBackground();
+		}
+	}
 }

briar-android/src/main/java/org/briarproject/briar/android/BriarService.java

@@ -1,7 +1,5 @@
 package org.briarproject.briar.android;
 
-import android.app.ActivityManager;
-import android.app.ActivityManager.RunningAppProcessInfo;
 import android.app.Notification;
 import android.app.NotificationChannel;
 import android.app.NotificationManager;
@@ -35,7 +33,6 @@ import java.util.logging.Logger;
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
-import static android.app.ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND;
 import static android.app.NotificationManager.IMPORTANCE_DEFAULT;
 import static android.app.NotificationManager.IMPORTANCE_NONE;
 import static android.app.PendingIntent.FLAG_UPDATE_CURRENT;
@@ -74,6 +71,7 @@ public class BriarService extends Service {
 
 	@Nullable
 	private BroadcastReceiver receiver = null;
+	private BriarApplication app;
 
 	@Inject
 	AndroidNotificationManager notificationManager;
@@ -93,8 +91,8 @@ public class BriarService extends Service {
 	public void onCreate() {
 		super.onCreate();
 
-		BriarApplication application = (BriarApplication) getApplication();
-		application.getApplicationComponent().inject(this);
+		app = (BriarApplication) getApplication();
+		app.getApplicationComponent().inject(this);
 
 		LOG.info("Created");
 		if (created.getAndSet(true)) {
@@ -220,8 +218,8 @@ public class BriarService extends Service {
 	public void onLowMemory() {
 		super.onLowMemory();
 		LOG.warning("Memory is low");
-		// Clear the UI - this is done in onTrimMemory() if SDK_INT >= 16
-		if (SDK_INT < 16) hideUi();
+		// If we're not in the foreground, clear the UI to save memory
+		if (app.isRunningInBackground()) hideUi();
 	}
 
 	@Override
@@ -235,20 +233,16 @@ public class BriarService extends Service {
 			LOG.info("Trim memory: near middle of LRU list");
 		} else if (level == TRIM_MEMORY_COMPLETE) {
 			LOG.info("Trim memory: near end of LRU list");
-		} else if (SDK_INT >= 16) {
-			if (level == TRIM_MEMORY_RUNNING_MODERATE) {
-				LOG.info("Trim memory: running moderately low");
-			} else if (level == TRIM_MEMORY_RUNNING_LOW) {
-				LOG.info("Trim memory: running low");
-			} else if (level == TRIM_MEMORY_RUNNING_CRITICAL) {
-				LOG.info("Trim memory: running critically low");
-				// If we're not in the foreground, clear the UI to save memory
-				RunningAppProcessInfo info = new RunningAppProcessInfo();
-				ActivityManager.getMyMemoryState(info);
-				if (info.importance != IMPORTANCE_FOREGROUND) hideUi();
-			} else if (LOG.isLoggable(INFO)) {
-				LOG.info("Trim memory: unknown level " + level);
-			}
+		} else if (level == TRIM_MEMORY_RUNNING_MODERATE) {
+			LOG.info("Trim memory: running moderately low");
+		} else if (level == TRIM_MEMORY_RUNNING_LOW) {
+			LOG.info("Trim memory: running low");
+		} else if (level == TRIM_MEMORY_RUNNING_CRITICAL) {
+			// This level may be received if SDK_INT < 16, although the
+			// constant isn't declared until API level 16
+			LOG.warning("Trim memory: running critically low");
+			// If we're not in the foreground, clear the UI to save memory
+			if (app.isRunningInBackground()) hideUi();
 		} else if (LOG.isLoggable(INFO)) {
 			LOG.info("Trim memory: unknown level " + level);
 		}

briar-android/src/main/java/org/briarproject/briar/android/StartupFailureActivity.java

@@ -3,22 +3,29 @@ package org.briarproject.briar.android;
 import android.app.NotificationManager;
 import android.content.Intent;
 import android.os.Bundle;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.activity.BaseActivity;
 import org.briarproject.briar.android.fragment.BaseFragment.BaseFragmentListener;
 import org.briarproject.briar.android.fragment.ErrorFragment;
 
+import static java.util.Objects.requireNonNull;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.StartResult;
 import static org.briarproject.briar.android.BriarService.EXTRA_NOTIFICATION_ID;
 import static org.briarproject.briar.android.BriarService.EXTRA_START_RESULT;
 
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
 public class StartupFailureActivity extends BaseActivity implements
 		BaseFragmentListener {
 
 	@Override
-	public void onCreate(Bundle state) {
+	public void onCreate(@Nullable Bundle state) {
 		super.onCreate(state);
 
 		setContentView(R.layout.activity_fragment_container);
@@ -38,7 +45,7 @@ public class StartupFailureActivity extends BaseActivity implements
 		// cancel notification
 		if (notificationId > -1) {
 			Object o = getSystemService(NOTIFICATION_SERVICE);
-			NotificationManager nm = (NotificationManager) o;
+			NotificationManager nm = (NotificationManager) requireNonNull(o);
 			nm.cancel(notificationId);
 		}
 
@@ -66,7 +73,7 @@ public class StartupFailureActivity extends BaseActivity implements
 	}
 
 	@Override
-	public void runOnDbThread(Runnable runnable) {
+	public void runOnDbThread(@NonNull Runnable runnable) {
 		throw new AssertionError("Deprecated and should not be used");
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/activity/ActivityComponent.java

@@ -20,6 +20,7 @@ import org.briarproject.briar.android.contact.ContactModule;
 import org.briarproject.briar.android.conversation.AliasDialogFragment;
 import org.briarproject.briar.android.conversation.ConversationActivity;
 import org.briarproject.briar.android.conversation.ImageActivity;
+import org.briarproject.briar.android.conversation.ImageFragment;
 import org.briarproject.briar.android.forum.CreateForumActivity;
 import org.briarproject.briar.android.forum.ForumActivity;
 import org.briarproject.briar.android.forum.ForumListFragment;
@@ -30,7 +31,6 @@ import org.briarproject.briar.android.introduction.IntroductionActivity;
 import org.briarproject.briar.android.introduction.IntroductionMessageFragment;
 import org.briarproject.briar.android.keyagreement.ContactExchangeActivity;
 import org.briarproject.briar.android.keyagreement.ContactExchangeErrorFragment;
-import org.briarproject.briar.android.keyagreement.IntroFragment;
 import org.briarproject.briar.android.keyagreement.KeyAgreementActivity;
 import org.briarproject.briar.android.keyagreement.KeyAgreementFragment;
 import org.briarproject.briar.android.login.AuthorNameFragment;
@@ -48,7 +48,6 @@ import org.briarproject.briar.android.privategroup.conversation.GroupActivity;
 import org.briarproject.briar.android.privategroup.conversation.GroupConversationModule;
 import org.briarproject.briar.android.privategroup.creation.CreateGroupActivity;
 import org.briarproject.briar.android.privategroup.creation.CreateGroupFragment;
-import org.briarproject.briar.android.privategroup.creation.CreateGroupMessageFragment;
 import org.briarproject.briar.android.privategroup.creation.CreateGroupModule;
 import org.briarproject.briar.android.privategroup.creation.GroupInviteActivity;
 import org.briarproject.briar.android.privategroup.creation.GroupInviteFragment;
@@ -69,10 +68,8 @@ import org.briarproject.briar.android.sharing.ForumInvitationActivity;
 import org.briarproject.briar.android.sharing.ForumSharingStatusActivity;
 import org.briarproject.briar.android.sharing.ShareBlogActivity;
 import org.briarproject.briar.android.sharing.ShareBlogFragment;
-import org.briarproject.briar.android.sharing.ShareBlogMessageFragment;
 import org.briarproject.briar.android.sharing.ShareForumActivity;
 import org.briarproject.briar.android.sharing.ShareForumFragment;
-import org.briarproject.briar.android.sharing.ShareForumMessageFragment;
 import org.briarproject.briar.android.sharing.SharingModule;
 import org.briarproject.briar.android.splash.SplashScreenActivity;
 import org.briarproject.briar.android.test.TestDataActivity;
@@ -182,8 +179,6 @@ public interface ActivityComponent {
 
 	void inject(CreateGroupFragment fragment);
 
-	void inject(CreateGroupMessageFragment fragment);
-
 	void inject(GroupListFragment fragment);
 
 	void inject(GroupInviteFragment fragment);
@@ -194,20 +189,14 @@ public interface ActivityComponent {
 
 	void inject(FeedFragment fragment);
 
-	void inject(IntroFragment fragment);
-
 	void inject(KeyAgreementFragment fragment);
 
 	void inject(ContactChooserFragment fragment);
 
 	void inject(ShareForumFragment fragment);
 
-	void inject(ShareForumMessageFragment fragment);
-
 	void inject(ShareBlogFragment fragment);
 
-	void inject(ShareBlogMessageFragment fragment);
-
 	void inject(IntroductionMessageFragment fragment);
 
 	void inject(SettingsFragment fragment);
@@ -218,4 +207,6 @@ public interface ActivityComponent {
 
 	void inject(AliasDialogFragment aliasDialogFragment);
 
+	void inject(ImageFragment imageFragment);
+
 }

briar-android/src/main/java/org/briarproject/briar/android/activity/BaseActivity.java

@@ -15,6 +15,8 @@ import android.view.ViewGroup.LayoutParams;
 import android.view.inputmethod.InputMethodManager;
 
 import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.AndroidComponent;
 import org.briarproject.briar.android.BriarApplication;
@@ -51,6 +53,8 @@ import static org.briarproject.briar.android.TestingConstants.PREVENT_SCREENSHOT
  * Warning: Some activities don't extend {@link BaseActivity}.
  *          E.g. {@link DevReportActivity}
  */
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
 public abstract class BaseActivity extends AppCompatActivity
 		implements DestroyableContext, OnTapFilteredListener {
 
@@ -77,6 +81,17 @@ public abstract class BaseActivity extends AppCompatActivity
 
 	@Override
 	public void onCreate(@Nullable Bundle state) {
+		// create the ActivityComponent *before* calling super.onCreate()
+		// because it already attaches fragments which need access
+		// to the component for their own injection
+		AndroidComponent applicationComponent =
+				((BriarApplication) getApplication()).getApplicationComponent();
+		activityComponent = DaggerActivityComponent.builder()
+				.androidComponent(applicationComponent)
+				.activityModule(getActivityModule())
+				.forumModule(getForumModule())
+				.build();
+		injectActivity(activityComponent);
 		super.onCreate(state);
 
 		// WARNING: When removing this or making it possible to turn it off,
@@ -86,17 +101,6 @@ public abstract class BaseActivity extends AppCompatActivity
 		//          unlock screen is shown.
 		if (PREVENT_SCREENSHOTS) getWindow().addFlags(FLAG_SECURE);
 
-		AndroidComponent applicationComponent =
-				((BriarApplication) getApplication()).getApplicationComponent();
-
-		activityComponent = DaggerActivityComponent.builder()
-				.androidComponent(applicationComponent)
-				.activityModule(getActivityModule())
-				.forumModule(getForumModule())
-				.build();
-
-		injectActivity(activityComponent);
-
 		for (ActivityLifecycleController alc : lifecycleControllers) {
 			alc.onActivityCreate(this);
 		}

briar-android/src/main/java/org/briarproject/briar/android/activity/BriarActivity.java

@@ -1,6 +1,5 @@
 package org.briarproject.briar.android.activity;
 
-import android.annotation.SuppressLint;
 import android.content.Intent;
 import android.support.annotation.RequiresApi;
 import android.support.v7.app.ActionBar;
@@ -10,6 +9,8 @@ import android.transition.Transition;
 import android.view.Window;
 import android.widget.CheckBox;
 
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.controller.BriarController;
 import org.briarproject.briar.android.controller.DbController;
@@ -36,7 +37,8 @@ import static org.briarproject.briar.android.util.UiUtils.excludeSystemUi;
 import static org.briarproject.briar.android.util.UiUtils.getDozeWhitelistingIntent;
 import static org.briarproject.briar.android.util.UiUtils.isSamsung7;
 
-@SuppressLint("Registered")
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
 public abstract class BriarActivity extends BaseActivity {
 
 	public static final String GROUP_ID = "briar.GROUP_ID";
@@ -60,7 +62,8 @@ public abstract class BriarActivity extends BaseActivity {
 	}
 
 	@Override
-	protected void onActivityResult(int request, int result, Intent data) {
+	protected void onActivityResult(int request, int result,
+			@Nullable Intent data) {
 		super.onActivityResult(request, result, data);
 		if (request == REQUEST_PASSWORD) {
 			// The result can be RESULT_CANCELED if there's no account
@@ -89,7 +92,7 @@ public abstract class BriarActivity extends BaseActivity {
 		} else if (lockManager.isLocked() && !isFinishing()) {
 			// Also check that the activity isn't finishing already.
 			// This is possible if we finished in onActivityResult().
-			// Lauching another UnlockActivity would cause a loop.
+			// Launching another UnlockActivity would cause a loop.
 			Intent i = new Intent(this, UnlockActivity.class);
 			startActivityForResult(i, REQUEST_UNLOCK);
 		} else if (SDK_INT >= 23) {
@@ -111,6 +114,10 @@ public abstract class BriarActivity extends BaseActivity {
 		lockManager.onActivityStop();
 	}
 
+	protected boolean signedIn() {
+		return briarController.accountSignedIn();
+	}
+
 	/**
 	 * Sets the transition animations.
 	 * @param enterTransition used to move views into initial positions

briar-android/src/main/java/org/briarproject/briar/android/blog/BasePostFragment.java

@@ -24,6 +24,8 @@ import javax.annotation.Nullable;
 import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
 import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
+import static java.util.Objects.requireNonNull;
+import static java.util.logging.Logger.getLogger;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
 import static org.briarproject.briar.android.util.UiUtils.MIN_DATE_RESOLUTION;
 
@@ -35,7 +37,7 @@ abstract class BasePostFragment extends BaseFragment {
 	static final String POST_ID = "briar.POST_ID";
 
 	private static final Logger LOG =
-			Logger.getLogger(BasePostFragment.class.getName());
+			getLogger(BasePostFragment.class.getName());
 
 	private final Handler handler = new Handler(Looper.getMainLooper());
 
@@ -52,7 +54,7 @@ abstract class BasePostFragment extends BaseFragment {
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
 		// retrieve MessageId of blog post from arguments
-		byte[] p = getArguments().getByteArray(POST_ID);
+		byte[] p = requireNonNull(getArguments()).getByteArray(POST_ID);
 		if (p == null) throw new IllegalStateException("No post ID in args");
 		postId = new MessageId(p);
 
@@ -68,6 +70,7 @@ abstract class BasePostFragment extends BaseFragment {
 
 			@Override
 			public void onAuthorClick(BlogPostItem post) {
+				if (getContext() == null) return;
 				Intent i = new Intent(getContext(), BlogActivity.class);
 				i.putExtra(GROUP_ID, post.getGroupId().getBytes());
 				i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogFragment.java

@@ -43,6 +43,7 @@ import javax.inject.Inject;
 import static android.app.Activity.RESULT_OK;
 import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
 import static android.widget.Toast.LENGTH_SHORT;
+import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_SHARE_BLOG;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_WRITE_BLOG_POST;
@@ -69,7 +70,6 @@ public class BlogFragment extends BaseFragment
 	private boolean isMyBlog = false, canDeleteBlog = false;
 
 	static BlogFragment newInstance(GroupId groupId) {
-
 		BlogFragment f = new BlogFragment();
 
 		Bundle bundle = new Bundle();
@@ -79,20 +79,27 @@ public class BlogFragment extends BaseFragment
 		return f;
 	}
 
+	@Override
+	public void injectFragment(ActivityComponent component) {
+		component.inject(this);
+		blogController.setBlogSharingListener(this);
+		sharingController.setSharingListener(this);
+	}
+
 	@Nullable
 	@Override
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-		Bundle args = getArguments();
+		Bundle args = requireNonNull(getArguments());
 		byte[] b = args.getByteArray(GROUP_ID);
 		if (b == null) throw new IllegalStateException("No group ID in args");
 		groupId = new GroupId(b);
 
 		View v = inflater.inflate(R.layout.fragment_blog, container, false);
 
-		adapter =
-				new BlogPostAdapter(getActivity(), this, getFragmentManager());
+		adapter = new BlogPostAdapter(requireNonNull(getActivity()), this,
+				getFragmentManager());
 		list = v.findViewById(R.id.postList);
 		list.setLayoutManager(new LinearLayoutManager(getActivity()));
 		list.setAdapter(adapter);
@@ -102,13 +109,6 @@ public class BlogFragment extends BaseFragment
 		return v;
 	}
 
-	@Override
-	public void injectFragment(ActivityComponent component) {
-		component.inject(this);
-		blogController.setBlogSharingListener(this);
-		sharingController.setSharingListener(this);
-	}
-
 	@Override
 	public void onStart() {
 		super.onStart();
@@ -218,7 +218,10 @@ public class BlogFragment extends BaseFragment
 
 	@Override
 	public void onAuthorClick(BlogPostItem post) {
-		if (post.getGroupId().equals(groupId)) return; // We're already there
+		if (post.getGroupId().equals(groupId) || getContext() == null) {
+			// We're already there
+			return;
+		}
 		Intent i = new Intent(getContext(), BlogActivity.class);
 		i.putExtra(GROUP_ID, post.getGroupId().getBytes());
 		i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedFragment.java

@@ -35,6 +35,7 @@ import javax.inject.Inject;
 import static android.app.Activity.RESULT_OK;
 import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
 import static android.support.design.widget.Snackbar.LENGTH_LONG;
+import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_WRITE_BLOG_POST;
 
@@ -64,13 +65,18 @@ public class FeedFragment extends BaseFragment implements
 		return f;
 	}
 
+	@Override
+	public void injectFragment(ActivityComponent component) {
+		component.inject(this);
+		feedController.setFeedListener(this);
+	}
+
 	@Nullable
 	@Override
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-
-		getActivity().setTitle(R.string.blogs_button);
+		requireNonNull(getActivity()).setTitle(R.string.blogs_button);
 
 		View v = inflater.inflate(R.layout.fragment_blog, container, false);
 
@@ -88,12 +94,6 @@ public class FeedFragment extends BaseFragment implements
 		return v;
 	}
 
-	@Override
-	public void injectFragment(ActivityComponent component) {
-		component.inject(this);
-		feedController.setFeedListener(this);
-	}
-
 	@Override
 	public void onActivityResult(int requestCode, int resultCode, Intent data) {
 		super.onActivityResult(requestCode, resultCode, data);

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedPostFragment.java

@@ -17,6 +17,7 @@ import org.briarproject.briar.android.controller.handler.UiResultExceptionHandle
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
+import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
 
 @UiThread
@@ -42,13 +43,17 @@ public class FeedPostFragment extends BasePostFragment {
 		return f;
 	}
 
+	@Override
+	public void injectFragment(ActivityComponent component) {
+		component.inject(this);
+	}
+
 	@Nullable
 	@Override
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-
-		Bundle args = getArguments();
+		Bundle args = requireNonNull(getArguments());
 		byte[] b = args.getByteArray(GROUP_ID);
 		if (b == null) throw new IllegalStateException("No group ID in args");
 		blogId = new GroupId(b);
@@ -61,11 +66,6 @@ public class FeedPostFragment extends BasePostFragment {
 		return TAG;
 	}
 
-	@Override
-	public void injectFragment(ActivityComponent component) {
-		component.inject(this);
-	}
-
 	@Override
 	public void onStart() {
 		super.onStart();

briar-android/src/main/java/org/briarproject/briar/android/blog/ReblogFragment.java

@@ -31,6 +31,7 @@ import static android.view.View.FOCUS_DOWN;
 import static android.view.View.GONE;
 import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
+import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
 import static org.briarproject.briar.android.blog.BasePostFragment.POST_ID;
 import static org.briarproject.briar.api.blog.BlogConstants.MAX_BLOG_POST_TEXT_LENGTH;
@@ -42,8 +43,6 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 	public static final String TAG = ReblogFragment.class.getName();
 
 	private ViewHolder ui;
-	private GroupId blogId;
-	private MessageId postId;
 	private BlogPostItem item;
 
 	@Inject
@@ -75,9 +74,11 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
 
-		Bundle args = getArguments();
-		blogId = new GroupId(args.getByteArray(GROUP_ID));
-		postId = new MessageId(args.getByteArray(POST_ID));
+		Bundle args = requireNonNull(getArguments());
+		GroupId blogId =
+				new GroupId(requireNonNull(args.getByteArray(GROUP_ID)));
+		MessageId postId =
+				new MessageId(requireNonNull(args.getByteArray(POST_ID)));
 
 		View v = inflater.inflate(R.layout.fragment_reblog, container, false);
 		ui = new ViewHolder(v);
@@ -89,14 +90,6 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 		ui.input.setMaxTextLength(MAX_BLOG_POST_TEXT_LENGTH);
 		showProgressBar();
 
-		return v;
-	}
-
-	@Override
-	public void onStart() {
-		super.onStart();
-
-		// TODO: Load blog post when fragment is created. #631
 		feedController.loadBlogPost(blogId, postId,
 				new UiResultExceptionHandler<BlogPostItem, DbException>(
 						this) {
@@ -111,6 +104,8 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 						handleDbException(exception);
 					}
 				});
+
+		return v;
 	}
 
 	private void bindViewHolder() {

briar-android/src/main/java/org/briarproject/briar/android/contact/ContactListFragment.java

@@ -51,11 +51,13 @@ import javax.inject.Inject;
 import static android.os.Build.VERSION.SDK_INT;
 import static android.support.v4.app.ActivityOptionsCompat.makeSceneTransitionAnimation;
 import static android.support.v4.view.ViewCompat.getTransitionName;
+import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.LogUtils.now;
 import static org.briarproject.briar.android.conversation.ConversationActivity.CONTACT_ID;
+import static org.briarproject.briar.android.util.UiUtils.isSamsung7;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
@@ -102,8 +104,7 @@ public class ContactListFragment extends BaseFragment implements EventListener {
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-
-		getActivity().setTitle(R.string.contact_list_button);
+		requireNonNull(getActivity()).setTitle(R.string.contact_list_button);
 
 		View contentView = inflater.inflate(R.layout.list, container, false);
 
@@ -114,7 +115,7 @@ public class ContactListFragment extends BaseFragment implements EventListener {
 					ContactId contactId = item.getContact().getId();
 					i.putExtra(CONTACT_ID, contactId.getInt());
 
-					if (SDK_INT >= 23) {
+					if (SDK_INT >= 23 && !isSamsung7()) {
 						ContactListItemViewHolder holder =
 								(ContactListItemViewHolder) list
 										.getRecyclerView()

briar-android/src/main/java/org/briarproject/briar/android/contactselection/BaseContactSelectorFragment.java

@@ -25,6 +25,7 @@ import java.util.Collection;
 
 import javax.annotation.Nullable;
 
+import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
 import static org.briarproject.briar.android.contactselection.ContactSelectorActivity.CONTACTS;
 import static org.briarproject.briar.android.contactselection.ContactSelectorActivity.getContactsFromIds;
@@ -50,10 +51,10 @@ public abstract class BaseContactSelectorFragment<I extends SelectableContactIte
 	}
 
 	@Override
-	public void onCreate(Bundle savedInstanceState) {
+	public void onCreate(@Nullable Bundle savedInstanceState) {
 		super.onCreate(savedInstanceState);
 
-		Bundle args = getArguments();
+		Bundle args = requireNonNull(getArguments());
 		byte[] b = args.getByteArray(GROUP_ID);
 		if (b == null) throw new IllegalStateException("No GroupId");
 		groupId = new GroupId(b);
@@ -72,7 +73,7 @@ public abstract class BaseContactSelectorFragment<I extends SelectableContactIte
 		list.setEmptyImage(R.drawable.ic_empty_state_contact_list);
 		list.setEmptyText(getString(R.string.no_contacts_selector));
 		list.setEmptyAction(getString(R.string.no_contacts_selector_action));
-		adapter = getAdapter(getContext(), this);
+		adapter = getAdapter(requireNonNull(getContext()), this);
 		list.setAdapter(adapter);
 
 		// restore selected contacts if available

briar-android/src/main/java/org/briarproject/briar/android/conversation/AliasDialogFragment.java

@@ -39,8 +39,8 @@ public class AliasDialogFragment extends AppCompatDialogFragment {
 
 		setStyle(STYLE_NO_TITLE, R.style.BriarDialogTheme);
 
-		if (getActivity() == null) return;
-		((BriarActivity) getActivity()).getActivityComponent().inject(this);
+		BriarActivity a = (BriarActivity) requireNonNull(getActivity());
+		a.getActivityComponent().inject(this);
 		viewModel = ViewModelProviders.of(getActivity(), viewModelFactory)
 				.get(ConversationViewModel.class);
 	}
@@ -48,7 +48,6 @@ public class AliasDialogFragment extends AppCompatDialogFragment {
 	@Override
 	public View onCreateView(@NonNull LayoutInflater inflater,
 			ViewGroup container, Bundle savedInstanceState) {
-
 		View v = inflater.inflate(R.layout.fragment_alias_dialog, container,
 				false);
 
@@ -69,4 +68,5 @@ public class AliasDialogFragment extends AppCompatDialogFragment {
 
 		return v;
 	}
+
 }

briar-android/src/main/java/org/briarproject/briar/android/conversation/AttachmentController.java

@@ -1,17 +1,19 @@
 package org.briarproject.briar.android.conversation;
 
-import android.content.res.Resources;
 import android.graphics.BitmapFactory;
+import android.graphics.BitmapFactory.Options;
 import android.support.annotation.Nullable;
 import android.support.media.ExifInterface;
 import android.webkit.MimeTypeMap;
 
+import com.bumptech.glide.util.MarkEnforcingInputStream;
+
 import org.briarproject.bramble.api.Pair;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.briar.R;
+import org.briarproject.briar.android.conversation.ImageHelper.DecodeResult;
 import org.briarproject.briar.api.messaging.Attachment;
 import org.briarproject.briar.api.messaging.AttachmentHeader;
 import org.briarproject.briar.api.messaging.MessagingManager;
@@ -44,8 +46,10 @@ class AttachmentController {
 
 	private static final Logger LOG =
 			getLogger(AttachmentController.class.getName());
+	private static final int READ_LIMIT = 1024 * 8192;
 
 	private final MessagingManager messagingManager;
+	private final ImageHelper imageHelper;
 	private final int defaultSize;
 	private final int minWidth, maxWidth;
 	private final int minHeight, maxHeight;
@@ -53,18 +57,38 @@ class AttachmentController {
 	private final Map<MessageId, List<AttachmentItem>> attachmentCache =
 			new ConcurrentHashMap<>();
 
-	AttachmentController(MessagingManager messagingManager, Resources res) {
+	AttachmentController(MessagingManager messagingManager,
+			AttachmentDimensions dimensions, ImageHelper imageHelper) {
 		this.messagingManager = messagingManager;
-		defaultSize =
-				res.getDimensionPixelSize(R.dimen.message_bubble_image_default);
-		minWidth = res.getDimensionPixelSize(
-				R.dimen.message_bubble_image_min_width);
-		maxWidth = res.getDimensionPixelSize(
-				R.dimen.message_bubble_image_max_width);
-		minHeight = res.getDimensionPixelSize(
-				R.dimen.message_bubble_image_min_height);
-		maxHeight = res.getDimensionPixelSize(
-				R.dimen.message_bubble_image_max_height);
+		this.imageHelper = imageHelper;
+		defaultSize = dimensions.defaultSize;
+		minWidth = dimensions.minWidth;
+		maxWidth = dimensions.maxWidth;
+		minHeight = dimensions.minHeight;
+		maxHeight = dimensions.maxHeight;
+	}
+
+	AttachmentController(MessagingManager messagingManager,
+			AttachmentDimensions dimensions) {
+		this(messagingManager, dimensions, new ImageHelper() {
+			@Override
+			public DecodeResult decodeStream(InputStream is) {
+				Options options = new Options();
+				options.inJustDecodeBounds = true;
+				BitmapFactory.decodeStream(is, null, options);
+				String mimeType = options.outMimeType;
+				if (mimeType == null) mimeType = "";
+				return new DecodeResult(options.outWidth, options.outHeight,
+						mimeType);
+			}
+
+			@Nullable
+			@Override
+			public String getExtensionFromMimeType(String mimeType) {
+				MimeTypeMap mimeTypeMap = MimeTypeMap.getSingleton();
+				return mimeTypeMap.getExtensionFromMimeType(mimeType);
+			}
+		});
 	}
 
 	void put(MessageId messageId, List<AttachmentItem> attachments) {
@@ -83,8 +107,7 @@ class AttachmentController {
 		List<Pair<AttachmentHeader, Attachment>> attachments =
 				new ArrayList<>(headers.size());
 		for (AttachmentHeader h : headers) {
-			Attachment a =
-					messagingManager.getAttachment(h.getMessageId());
+			Attachment a = messagingManager.getAttachment(h.getMessageId());
 			attachments.add(new Pair<>(h, a));
 		}
 		logDuration(LOG, "Loading attachment", start);
@@ -93,7 +116,7 @@ class AttachmentController {
 
 	/**
 	 * Creates {@link AttachmentItem}s from the passed headers and Attachments.
-	 *
+	 * <p>
 	 * Note: This closes the {@link Attachment}'s {@link InputStream}.
 	 */
 	List<AttachmentItem> getAttachmentItems(
@@ -117,7 +140,7 @@ class AttachmentController {
 		MessageId messageId = h.getMessageId();
 		if (!needsSize) {
 			String mimeType = h.getContentType();
-			String extension = getExtensionFromMimeType(mimeType);
+			String extension = imageHelper.getExtensionFromMimeType(mimeType);
 			boolean hasError = false;
 			if (extension == null) {
 				extension = "";
@@ -128,8 +151,9 @@ class AttachmentController {
 		}
 
 		Size size = new Size();
-		InputStream is = new BufferedInputStream(a.getStream());
-		is.mark(Integer.MAX_VALUE);
+		InputStream is = new MarkEnforcingInputStream(
+				new BufferedInputStream(a.getStream()));
+		is.mark(READ_LIMIT);
 		try {
 			// use exif to get size
 			if (h.getContentType().equals("image/jpeg")) {
@@ -142,6 +166,8 @@ class AttachmentController {
 			// use BitmapFactory to get size
 			if (size.error) {
 				is.reset();
+				// need to mark again to re-add read limit
+				is.mark(READ_LIMIT);
 				size = getSizeFromBitmap(is);
 			}
 		} catch (IOException e) {
@@ -157,26 +183,18 @@ class AttachmentController {
 					getThumbnailSize(size.width, size.height, size.mimeType);
 		}
 		// get file extension
-		String extension = getExtensionFromMimeType(size.mimeType);
-		if (extension == null) {
-			return new AttachmentItem(messageId, 0, 0, "", "", 0, 0, true);
-		}
+		String extension = imageHelper.getExtensionFromMimeType(size.mimeType);
+		boolean hasError = extension == null || size.error;
+		if (extension == null) extension = "";
 		return new AttachmentItem(messageId, size.width, size.height,
 				size.mimeType, extension, thumbnailSize.width,
-				thumbnailSize.height, size.error);
-	}
-
-	@Nullable
-	private String getExtensionFromMimeType(String mimeType) {
-		MimeTypeMap mimeTypeMap = MimeTypeMap.getSingleton();
-		return mimeTypeMap.getExtensionFromMimeType(mimeType);
+				thumbnailSize.height, hasError);
 	}
 
 	/**
 	 * Gets the size of a JPEG {@link InputStream} if EXIF info is available.
 	 */
-	private static Size getSizeFromExif(InputStream is)
-			throws IOException {
+	private Size getSizeFromExif(InputStream is) throws IOException {
 		ExifInterface exif = new ExifInterface(is);
 		// these can return 0 independent of default value
 		int width = exif.getAttributeInt(TAG_IMAGE_WIDTH, 0);
@@ -196,14 +214,10 @@ class AttachmentController {
 	/**
 	 * Gets the size of any image {@link InputStream}.
 	 */
-	private static Size getSizeFromBitmap(InputStream is) {
-		BitmapFactory.Options options = new BitmapFactory.Options();
-		options.inJustDecodeBounds = true;
-		BitmapFactory.decodeStream(is, null, options);
-		if (options.outWidth < 1 || options.outHeight < 1)
-			return new Size();
-		return new Size(options.outWidth, options.outHeight,
-				options.outMimeType);
+	private Size getSizeFromBitmap(InputStream is) {
+		DecodeResult result = imageHelper.decodeStream(is);
+		if (result.width < 1 || result.height < 1) return new Size();
+		return new Size(result.width, result.height, result.mimeType);
 	}
 
 	private Size getThumbnailSize(int width, int height, String mimeType) {

briar-android/src/main/java/org/briarproject/briar/android/conversation/AttachmentDimensions.java

@@ -0,0 +1,39 @@
+package org.briarproject.briar.android.conversation;
+
+import android.content.res.Resources;
+import android.support.annotation.VisibleForTesting;
+
+import org.briarproject.briar.R;
+
+class AttachmentDimensions {
+
+	final int defaultSize;
+	final int minWidth, maxWidth;
+	final int minHeight, maxHeight;
+
+	@VisibleForTesting
+	AttachmentDimensions(int defaultSize, int minWidth, int maxWidth,
+			int minHeight, int maxHeight) {
+		this.defaultSize = defaultSize;
+		this.minWidth = minWidth;
+		this.maxWidth = maxWidth;
+		this.minHeight = minHeight;
+		this.maxHeight = maxHeight;
+	}
+
+	static AttachmentDimensions getAttachmentDimensions(Resources res) {
+		int defaultSize =
+				res.getDimensionPixelSize(R.dimen.message_bubble_image_default);
+		int minWidth = res.getDimensionPixelSize(
+				R.dimen.message_bubble_image_min_width);
+		int maxWidth = res.getDimensionPixelSize(
+				R.dimen.message_bubble_image_max_width);
+		int minHeight = res.getDimensionPixelSize(
+				R.dimen.message_bubble_image_min_height);
+		int maxHeight = res.getDimensionPixelSize(
+				R.dimen.message_bubble_image_max_height);
+		return new AttachmentDimensions(defaultSize, minWidth, maxWidth,
+				minHeight, minHeight);
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/conversation/AttachmentItem.java

@@ -2,10 +2,13 @@ package org.briarproject.briar.android.conversation;
 
 import android.os.Parcel;
 import android.os.Parcelable;
+import android.support.annotation.Nullable;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageId;
 
+import java.util.concurrent.atomic.AtomicLong;
+
 import javax.annotation.concurrent.Immutable;
 
 @Immutable
@@ -17,6 +20,7 @@ public class AttachmentItem implements Parcelable {
 	private final String mimeType, extension;
 	private final int thumbnailWidth, thumbnailHeight;
 	private final boolean hasError;
+	private final long instanceId;
 
 	public static final Creator<AttachmentItem> CREATOR =
 			new Creator<AttachmentItem>() {
@@ -31,6 +35,8 @@ public class AttachmentItem implements Parcelable {
 				}
 			};
 
+	private static final AtomicLong NEXT_INSTANCE_ID = new AtomicLong(0);
+
 	AttachmentItem(MessageId messageId, int width, int height, String mimeType,
 			String extension, int thumbnailWidth, int thumbnailHeight,
 			boolean hasError) {
@@ -42,6 +48,7 @@ public class AttachmentItem implements Parcelable {
 		this.thumbnailWidth = thumbnailWidth;
 		this.thumbnailHeight = thumbnailHeight;
 		this.hasError = hasError;
+		instanceId = NEXT_INSTANCE_ID.getAndIncrement();
 	}
 
 	protected AttachmentItem(Parcel in) {
@@ -55,6 +62,7 @@ public class AttachmentItem implements Parcelable {
 		thumbnailWidth = in.readInt();
 		thumbnailHeight = in.readInt();
 		hasError = in.readByte() != 0;
+		instanceId = in.readLong();
 	}
 
 	public MessageId getMessageId() {
@@ -89,9 +97,8 @@ public class AttachmentItem implements Parcelable {
 		return hasError;
 	}
 
-	// TODO use counter instead, because in theory one attachment can appear in more than one messages
 	String getTransitionName() {
-		return String.valueOf(messageId.hashCode());
+		return String.valueOf(instanceId);
 	}
 
 	@Override
@@ -109,6 +116,13 @@ public class AttachmentItem implements Parcelable {
 		dest.writeInt(thumbnailWidth);
 		dest.writeInt(thumbnailHeight);
 		dest.writeByte((byte) (hasError ? 1 : 0));
+		dest.writeLong(instanceId);
+	}
+
+	@Override
+	public boolean equals(@Nullable Object o) {
+		return o instanceof AttachmentItem &&
+				instanceId == ((AttachmentItem) o).instanceId;
 	}
 
 }

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationActivity.java

@@ -8,6 +8,7 @@ import android.content.DialogInterface;
 import android.content.Intent;
 import android.net.Uri;
 import android.os.Bundle;
+import android.os.Parcelable;
 import android.support.annotation.Nullable;
 import android.support.annotation.UiThread;
 import android.support.design.widget.Snackbar;
@@ -45,7 +46,6 @@ import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.plugin.ConnectionRegistry;
 import org.briarproject.bramble.api.plugin.event.ContactConnectedEvent;
 import org.briarproject.bramble.api.plugin.event.ContactDisconnectedEvent;
-import org.briarproject.bramble.api.settings.Settings;
 import org.briarproject.bramble.api.settings.SettingsManager;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.MessageId;
@@ -102,12 +102,12 @@ import im.delight.android.identicons.IdenticonDrawable;
 import uk.co.samuelwall.materialtaptargetprompt.MaterialTapTargetPrompt;
 import uk.co.samuelwall.materialtaptargetprompt.MaterialTapTargetPrompt.PromptStateChangeListener;
 
+import static android.arch.lifecycle.Lifecycle.State.STARTED;
 import static android.os.Build.VERSION.SDK_INT;
 import static android.support.v4.app.ActivityOptionsCompat.makeSceneTransitionAnimation;
 import static android.support.v4.view.ViewCompat.setTransitionName;
 import static android.support.v7.util.SortedList.INVALID_POSITION;
 import static android.view.Gravity.RIGHT;
-import static android.widget.Toast.LENGTH_LONG;
 import static android.widget.Toast.LENGTH_SHORT;
 import static java.util.Collections.emptyList;
 import static java.util.Collections.sort;
@@ -121,10 +121,10 @@ import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
 import static org.briarproject.briar.android.TestingConstants.FEATURE_FLAG_IMAGE_ATTACHMENTS;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_ATTACH_IMAGE;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_INTRODUCTION;
-import static org.briarproject.briar.android.conversation.ImageActivity.ATTACHMENT;
+import static org.briarproject.briar.android.conversation.ImageActivity.ATTACHMENTS;
+import static org.briarproject.briar.android.conversation.ImageActivity.ATTACHMENT_POSITION;
 import static org.briarproject.briar.android.conversation.ImageActivity.DATE;
 import static org.briarproject.briar.android.conversation.ImageActivity.NAME;
-import static org.briarproject.briar.android.settings.SettingsFragment.SETTINGS_NAMESPACE;
 import static org.briarproject.briar.android.util.UiUtils.getAvatarTransitionName;
 import static org.briarproject.briar.android.util.UiUtils.getBulbTransitionName;
 import static org.briarproject.briar.android.util.UiUtils.observeOnce;
@@ -142,8 +142,9 @@ public class ConversationActivity extends BriarActivity
 
 	private static final Logger LOG =
 			Logger.getLogger(ConversationActivity.class.getName());
-	private static final String SHOW_ONBOARDING_INTRODUCTION =
-			"showOnboardingIntroduction";
+
+	private static final int TRANSITION_DURATION_MS = 500;
+	private static final int ONBOARDING_DELAY_MS = 250;
 
 	@Inject
 	AndroidNotificationManager notificationManager;
@@ -152,21 +153,8 @@ public class ConversationActivity extends BriarActivity
 	@Inject
 	@CryptoExecutor
 	Executor cryptoExecutor;
-
-	private final Map<MessageId, String> textCache = new ConcurrentHashMap<>();
-	private AttachmentController attachmentController;
-
-	private ConversationViewModel viewModel;
-	private ConversationVisitor visitor;
-	private ConversationAdapter adapter;
-	private Toolbar toolbar;
-	private CircleImageView toolbarAvatar;
-	private ImageView toolbarStatus;
-	private TextView toolbarTitle;
-	private BriarRecyclerView list;
-	private LinearLayoutManager layoutManager;
-	private TextInputView textInputView;
-	private TextSendController sendController;
+	@Inject
+	ViewModelProvider.Factory viewModelFactory;
 
 	// Fields that are accessed from background threads must be volatile
 	@Inject
@@ -189,22 +177,37 @@ public class ConversationActivity extends BriarActivity
 	volatile BlogSharingManager blogSharingManager;
 	@Inject
 	volatile GroupInvitationManager groupInvitationManager;
-	@Inject
-	ViewModelProvider.Factory viewModelFactory;
-
-	private volatile ContactId contactId;
 
+	private final Map<MessageId, String> textCache = new ConcurrentHashMap<>();
 	private final Observer<String> contactNameObserver = name -> {
 		requireNonNull(name);
 		loadMessages();
 	};
 
+	private AttachmentController attachmentController;
+	private ConversationViewModel viewModel;
+	private ConversationVisitor visitor;
+	private ConversationAdapter adapter;
+	private Toolbar toolbar;
+	private CircleImageView toolbarAvatar;
+	private ImageView toolbarStatus;
+	private TextView toolbarTitle;
+	private BriarRecyclerView list;
+	private LinearLayoutManager layoutManager;
+	private TextInputView textInputView;
+	private TextSendController sendController;
+	@Nullable
+	private Parcelable layoutManagerState;
+
+	private volatile ContactId contactId;
+
 	@Override
 	public void onCreate(@Nullable Bundle state) {
 		if (SDK_INT >= 21) {
 			// Spurious lint warning - using END causes a crash
 			@SuppressLint("RtlHardcoded")
 			Transition slide = new Slide(RIGHT);
+			slide.setDuration(TRANSITION_DURATION_MS);
 			setSceneTransitionAnimation(slide, null, slide);
 		}
 		super.onCreate(state);
@@ -216,7 +219,6 @@ public class ConversationActivity extends BriarActivity
 
 		viewModel = ViewModelProviders.of(this, viewModelFactory)
 				.get(ConversationViewModel.class);
-		viewModel.setContactId(contactId);
 		attachmentController = viewModel.getAttachmentController();
 
 		setContentView(R.layout.activity_conversation);
@@ -240,8 +242,8 @@ public class ConversationActivity extends BriarActivity
 			requireNonNull(deleted);
 			if (deleted) finish();
 		});
-		viewModel.getAddedPrivateMessage()
-				.observe(this, this::onAddedPrivateMessage);
+		viewModel.getAddedPrivateMessage().observe(this,
+				this::onAddedPrivateMessage);
 
 		setTransitionName(toolbarAvatar, getAvatarTransitionName(contactId));
 		setTransitionName(toolbarStatus, getBulbTransitionName(contactId));
@@ -260,12 +262,25 @@ public class ConversationActivity extends BriarActivity
 			ImagePreview imagePreview = findViewById(R.id.imagePreview);
 			sendController = new TextAttachmentController(textInputView,
 					imagePreview, this, this);
+			observeOnce(viewModel.hasImageSupport(), this, hasSupport -> {
+				if (hasSupport != null && hasSupport) {
+					// remove cast when removing FEATURE_FLAG_IMAGE_ATTACHMENTS
+					((TextAttachmentController) sendController)
+							.setImagesSupported();
+				}
+			});
 		} else {
 			sendController = new TextSendController(textInputView, this, false);
 		}
 		textInputView.setSendController(sendController);
 		textInputView.setMaxTextLength(MAX_PRIVATE_MESSAGE_TEXT_LENGTH);
 		textInputView.setEnabled(false);
+		textInputView.addOnKeyboardShownListener(this::scrollToBottom);
+	}
+
+	private void scrollToBottom() {
+		int items = adapter.getItemCount();
+		if (items > 0) list.scrollToPosition(items - 1);
 	}
 
 	@Override
@@ -274,7 +289,8 @@ public class ConversationActivity extends BriarActivity
 	}
 
 	@Override
-	protected void onActivityResult(int request, int result, Intent data) {
+	protected void onActivityResult(int request, int result,
+			@Nullable Intent data) {
 		super.onActivityResult(request, result, data);
 
 		if (request == REQUEST_INTRODUCTION && result == RESULT_OK) {
@@ -299,6 +315,16 @@ public class ConversationActivity extends BriarActivity
 		list.startPeriodicUpdate();
 	}
 
+	@Override
+	public void onResume() {
+		super.onResume();
+		// Trigger loading of contact data, noop if data was loaded already.
+		//
+		// We can only start loading data *after* we are sure
+		// the user has signed in. After sign-in, onCreate() isn't run again.
+		if (signedIn()) viewModel.setContactId(contactId);
+	}
+
 	@Override
 	public void onStop() {
 		super.onStop();
@@ -308,16 +334,39 @@ public class ConversationActivity extends BriarActivity
 		list.stopPeriodicUpdate();
 	}
 
+	@Override
+	protected void onSaveInstanceState(Bundle outState) {
+		super.onSaveInstanceState(outState);
+		if (layoutManager != null) {
+			layoutManagerState = layoutManager.onSaveInstanceState();
+			outState.putParcelable("layoutManager", layoutManagerState);
+		}
+	}
+
+	@Override
+	protected void onRestoreInstanceState(Bundle savedInstanceState) {
+		super.onRestoreInstanceState(savedInstanceState);
+		layoutManagerState = savedInstanceState.getParcelable("layoutManager");
+	}
+
 	@Override
 	public boolean onCreateOptionsMenu(Menu menu) {
 		// Inflate the menu items for use in the action bar
 		MenuInflater inflater = getMenuInflater();
 		inflater.inflate(R.menu.conversation_actions, menu);
 
-		enableIntroductionActionIfAvailable(
-				menu.findItem(R.id.action_introduction));
-		enableAliasActionIfAvailable(
-				menu.findItem(R.id.action_set_alias));
+		// enable introduction action if available
+		observeOnce(viewModel.showIntroductionAction(), this, enable -> {
+			if (enable != null && enable) {
+				menu.findItem(R.id.action_introduction).setEnabled(true);
+				// show introduction onboarding, if needed
+				observeOnce(viewModel.showIntroductionOnboarding(), this,
+						this::showIntroductionOnboarding);
+			}
+		});
+		// enable alias action if available
+		observeOnce(viewModel.getContact(), this, contact ->
+				menu.findItem(R.id.action_set_alias).setEnabled(true));
 
 		return super.onCreateOptionsMenu(menu);
 	}
@@ -380,33 +429,10 @@ public class ConversationActivity extends BriarActivity
 						Long.compare(b.getTimestamp(), a.getTimestamp()));
 				if (!sorted.isEmpty()) {
 					// If the latest header is a private message, eagerly load
-					// its text so we can set the scroll position correctly
+					// its size so we can set the scroll position correctly
 					ConversationMessageHeader latest = sorted.get(0);
 					if (latest instanceof PrivateMessageHeader) {
-						MessageId id = latest.getId();
-						PrivateMessageHeader h = (PrivateMessageHeader) latest;
-						if (h.hasText()) {
-							String text = textCache.get(id);
-							if (text == null) {
-								LOG.info(
-										"Eagerly loading text of latest message");
-								text = messagingManager.getMessageText(id);
-								textCache.put(id, text);
-							}
-						}
-						if (h.getAttachmentHeaders().size() == 1) {
-							List<AttachmentItem> items =
-									attachmentController.get(id);
-							if (items == null) {
-								LOG.info(
-										"Eagerly loading image size for latest message");
-								items = attachmentController.getAttachmentItems(
-										attachmentController
-												.getMessageAttachments(
-														h.getAttachmentHeaders()));
-								attachmentController.put(id, items);
-							}
-						}
+						eagerlyLoadMessageSize((PrivateMessageHeader) latest);
 					}
 				}
 				displayMessages(revision, sorted);
@@ -418,17 +444,51 @@ public class ConversationActivity extends BriarActivity
 		});
 	}
 
+	private void eagerlyLoadMessageSize(PrivateMessageHeader h)
+			throws DbException {
+		MessageId id = h.getId();
+		// If the message has text, load it
+		if (h.hasText()) {
+			String text = textCache.get(id);
+			if (text == null) {
+				LOG.info("Eagerly loading text for latest message");
+				text = messagingManager.getMessageText(id);
+				textCache.put(id, text);
+			}
+		}
+		// If the message has a single image, load its size - for multiple
+		// images we use a grid so the size is fixed
+		if (h.getAttachmentHeaders().size() == 1) {
+			List<AttachmentItem> items = attachmentController.get(id);
+			if (items == null) {
+				LOG.info("Eagerly loading image size for latest message");
+				items = attachmentController.getAttachmentItems(
+						attachmentController.getMessageAttachments(
+								h.getAttachmentHeaders()));
+				attachmentController.put(id, items);
+			}
+		}
+	}
+
 	private void displayMessages(int revision,
 			Collection<ConversationMessageHeader> headers) {
 		runOnUiThreadUnlessDestroyed(() -> {
 			if (revision == adapter.getRevision()) {
 				adapter.incrementRevision();
 				textInputView.setEnabled(true);
+				// start observing onboarding after enabling (only once, because
+				// we only update this when an onboarding should be shown)
+				observeOnce(viewModel.showImageOnboarding(), this,
+						this::showImageOnboarding);
 				List<ConversationItem> items = createItems(headers);
 				adapter.addAll(items);
 				list.showData();
-				// Scroll to the bottom
-				list.scrollToPosition(adapter.getItemCount() - 1);
+				if (layoutManagerState == null) {
+					scrollToBottom();
+				} else {
+					// Restore the previous scroll position
+					layoutManager.onRestoreInstanceState(layoutManagerState);
+				}
 			} else {
 				LOG.info("Concurrent update, reloading");
 				loadMessages();
@@ -469,14 +529,21 @@ public class ConversationActivity extends BriarActivity
 			Pair<Integer, ConversationMessageItem> pair =
 					adapter.getMessageItem(m);
 			if (pair != null) {
+				boolean scroll = shouldScrollWhenUpdatingMessage();
 				pair.getSecond().setText(text);
-				boolean bottom = adapter.isScrolledToBottom(layoutManager);
 				adapter.notifyItemChanged(pair.getFirst());
-				if (bottom) list.scrollToPosition(adapter.getItemCount() - 1);
+				if (scroll) scrollToBottom();
 			}
 		});
 	}
 
+	// When a message's text or attachments are loaded, scroll to the bottom
+	// if the conversation is visible and we were previously at the bottom
+	private boolean shouldScrollWhenUpdatingMessage() {
+		return getLifecycle().getCurrentState().isAtLeast(STARTED)
+				&& adapter.isScrolledToBottom(layoutManager);
+	}
+
 	private void loadMessageAttachments(MessageId messageId,
 			List<AttachmentHeader> headers) {
 		runOnDbThread(() -> {
@@ -500,10 +567,10 @@ public class ConversationActivity extends BriarActivity
 			Pair<Integer, ConversationMessageItem> pair =
 					adapter.getMessageItem(m);
 			if (pair != null) {
+				boolean scroll = shouldScrollWhenUpdatingMessage();
 				pair.getSecond().setAttachments(items);
-				boolean bottom = adapter.isScrolledToBottom(layoutManager);
 				adapter.notifyItemChanged(pair.getFirst());
-				if (bottom) list.scrollToPosition(adapter.getItemCount() - 1);
+				if (scroll) scrollToBottom();
 			}
 		});
 	}
@@ -552,10 +619,13 @@ public class ConversationActivity extends BriarActivity
 
 	private void addConversationItem(ConversationItem item) {
 		runOnUiThreadUnlessDestroyed(() -> {
-			boolean bottom = adapter.isScrolledToBottom(layoutManager);
 			adapter.incrementRevision();
 			adapter.add(item);
-			if (bottom) list.scrollToPosition(adapter.getItemCount() - 1);
+			// When adding a new message, scroll to the bottom if the
+			// conversation is visible, even if we're not currently at
+			// the bottom
+			if (getLifecycle().getCurrentState().isAtLeast(STARTED))
+				scrollToBottom();
 		});
 	}
 
@@ -651,74 +721,70 @@ public class ConversationActivity extends BriarActivity
 		});
 	}
 
-	private void enableIntroductionActionIfAvailable(MenuItem item) {
-		runOnDbThread(() -> {
-			try {
-				if (contactManager.getActiveContacts().size() > 1) {
-					enableIntroductionAction(item);
-					Settings settings =
-							settingsManager.getSettings(SETTINGS_NAMESPACE);
-					if (settings.getBoolean(SHOW_ONBOARDING_INTRODUCTION,
-							true)) {
-						showIntroductionOnboarding();
-					}
-				}
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-			}
-		});
+	private void showImageOnboarding(@Nullable Boolean show) {
+		if (show == null || !show) return;
+		if (SDK_INT >= 21) {
+			// show onboarding only after the enter transition has ended
+			// otherwise the tap target animation won't play
+			textInputView.postDelayed(this::showImageOnboarding,
+					TRANSITION_DURATION_MS + ONBOARDING_DELAY_MS);
+		} else {
+			showImageOnboarding();
+		}
 	}
 
-	private void enableAliasActionIfAvailable(MenuItem item) {
-		observeOnce(viewModel.getContact(), this, c -> item.setEnabled(true));
+	private void showImageOnboarding() {
+		// remove cast when removing FEATURE_FLAG_IMAGE_ATTACHMENTS
+		((TextAttachmentController) sendController)
+				.showImageOnboarding(this, () ->
+						viewModel.onImageOnboardingSeen());
 	}
 
-	private void enableIntroductionAction(MenuItem item) {
-		runOnUiThreadUnlessDestroyed(() -> item.setEnabled(true));
+	private void showIntroductionOnboarding(@Nullable Boolean show) {
+		if (show == null || !show) return;
+		if (SDK_INT >= 21) {
+			// show onboarding only after the enter transition has ended
+			// otherwise the tap target animation won't play
+			textInputView.postDelayed(this::showIntroductionOnboarding,
+					TRANSITION_DURATION_MS + ONBOARDING_DELAY_MS);
+		} else {
+			showIntroductionOnboarding();
+		}
 	}
 
 	private void showIntroductionOnboarding() {
-		runOnUiThreadUnlessDestroyed(() -> {
-			// find view of overflow icon
-			View target = null;
-			for (int i = 0; i < toolbar.getChildCount(); i++) {
-				if (toolbar.getChildAt(i) instanceof ActionMenuView) {
-					ActionMenuView menu =
-							(ActionMenuView) toolbar.getChildAt(i);
-					target = menu.getChildAt(menu.getChildCount() - 1);
-					break;
-				}
-			}
-			if (target == null) {
-				LOG.warning("No Overflow Icon found!");
-				return;
+		// find view of overflow icon
+		View target = null;
+		for (int i = 0; i < toolbar.getChildCount(); i++) {
+			if (toolbar.getChildAt(i) instanceof ActionMenuView) {
+				ActionMenuView menu = (ActionMenuView) toolbar.getChildAt(i);
+				// The overflow icon should be the last child of the menu
+				target = menu.getChildAt(menu.getChildCount() - 1);
+				// If the menu hasn't been populated yet, use the menu itself
+				// as the target
+				if (target == null) target = menu;
+				break;
 			}
+		}
+		if (target == null) {
+			LOG.warning("No Overflow Icon found!");
+			return;
+		}
 
-			PromptStateChangeListener listener = (prompt, state) -> {
-				if (state == STATE_DISMISSED || state == STATE_FINISHED) {
-					introductionOnboardingSeen();
-				}
-			};
-			new MaterialTapTargetPrompt.Builder(ConversationActivity.this,
-					R.style.OnboardingDialogTheme).setTarget(target)
-					.setPrimaryText(R.string.introduction_onboarding_title)
-					.setSecondaryText(R.string.introduction_onboarding_text)
-					.setIcon(R.drawable.ic_more_vert_accent)
-					.setPromptStateChangeListener(listener)
-					.show();
-		});
-	}
-
-	private void introductionOnboardingSeen() {
-		runOnDbThread(() -> {
-			try {
-				Settings settings = new Settings();
-				settings.putBoolean(SHOW_ONBOARDING_INTRODUCTION, false);
-				settingsManager.mergeSettings(settings, SETTINGS_NAMESPACE);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
+		PromptStateChangeListener listener = (prompt, state) -> {
+			if (state == STATE_DISMISSED || state == STATE_FINISHED) {
+				viewModel.onIntroductionOnboardingSeen();
 			}
-		});
+		};
+		new MaterialTapTargetPrompt.Builder(ConversationActivity.this,
+				R.style.OnboardingDialogTheme).setTarget(target)
+				.setPrimaryText(R.string.introduction_onboarding_title)
+				.setSecondaryText(R.string.introduction_onboarding_text)
+				.setIcon(R.drawable.ic_more_vert_accent)
+				.setBackgroundColour(
+						ContextCompat.getColor(this, R.color.briar_primary))
+				.setPromptStateChangeListener(listener)
+				.show();
 	}
 
 	@Override
@@ -812,19 +878,18 @@ public class ConversationActivity extends BriarActivity
 		} else {
 			name = getString(R.string.you);
 		}
+		ArrayList<AttachmentItem> attachments =
+				new ArrayList<>(messageItem.getAttachments());
 		Intent i = new Intent(this, ImageActivity.class);
-		i.putExtra(ATTACHMENT, item);
+		i.putParcelableArrayListExtra(ATTACHMENTS, attachments);
+		i.putExtra(ATTACHMENT_POSITION, attachments.indexOf(item));
 		i.putExtra(NAME, name);
 		i.putExtra(DATE, messageItem.getTime());
-		if (SDK_INT >= 23) {
-			String transitionName = item.getTransitionName();
-			ActivityOptionsCompat options =
-					makeSceneTransitionAnimation(this, view, transitionName);
-			ActivityCompat.startActivity(this, i, options.toBundle());
-		} else {
-			// work-around for android bug #224270
-			startActivity(i);
-		}
+		// restoring list position should not trigger android bug #224270
+		String transitionName = item.getTransitionName();
+		ActivityOptionsCompat options =
+				makeSceneTransitionAnimation(this, view, transitionName);
+		ActivityCompat.startActivity(this, i, options.toBundle());
 	}
 
 	@DatabaseExecutor

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationViewModel.java

@@ -16,11 +16,14 @@ import org.briarproject.bramble.api.contact.Contact;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.contact.ContactManager;
 import org.briarproject.bramble.api.crypto.CryptoExecutor;
+import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.NoSuchContactException;
 import org.briarproject.bramble.api.identity.AuthorId;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.settings.Settings;
+import org.briarproject.bramble.api.settings.SettingsManager;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.briar.android.util.UiUtils;
@@ -34,6 +37,7 @@ import org.briarproject.briar.api.messaging.PrivateMessageHeader;
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.List;
 import java.util.concurrent.Executor;
 import java.util.logging.Logger;
@@ -47,6 +51,8 @@ import static org.briarproject.bramble.util.IoUtils.tryToClose;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.LogUtils.now;
+import static org.briarproject.briar.android.conversation.AttachmentDimensions.getAttachmentDimensions;
+import static org.briarproject.briar.android.settings.SettingsFragment.SETTINGS_NAMESPACE;
 import static org.briarproject.briar.android.util.UiUtils.observeForeverOnce;
 
 @NotNullByDefault
@@ -54,13 +60,20 @@ public class ConversationViewModel extends AndroidViewModel {
 
 	private static Logger LOG =
 			getLogger(ConversationViewModel.class.getName());
+	private static final String SHOW_ONBOARDING_IMAGE =
+			"showOnboardingImage";
+	private static final String SHOW_ONBOARDING_INTRODUCTION =
+			"showOnboardingIntroduction";
 
 	@DatabaseExecutor
 	private final Executor dbExecutor;
 	@CryptoExecutor
 	private final Executor cryptoExecutor;
+	// TODO replace with TransactionManager once it exists
+	private final DatabaseComponent db;
 	private final MessagingManager messagingManager;
 	private final ContactManager contactManager;
+	private final SettingsManager settingsManager;
 	private final PrivateMessageFactory privateMessageFactory;
 	private final AttachmentController attachmentController;
 
@@ -71,6 +84,14 @@ public class ConversationViewModel extends AndroidViewModel {
 			Transformations.map(contact, c -> c.getAuthor().getId());
 	private final LiveData<String> contactName =
 			Transformations.map(contact, UiUtils::getContactDisplayName);
+	private final MutableLiveData<Boolean> imageSupport =
+			new MutableLiveData<>();
+	private final MutableLiveData<Boolean> showImageOnboarding =
+			new MutableLiveData<>();
+	private final MutableLiveData<Boolean> showIntroductionOnboarding =
+			new MutableLiveData<>();
+	private final MutableLiveData<Boolean> showIntroductionAction =
+			new MutableLiveData<>();
 	private final MutableLiveData<Boolean> contactDeleted =
 			new MutableLiveData<>();
 	private final MutableLiveData<GroupId> messagingGroupId =
@@ -81,38 +102,46 @@ public class ConversationViewModel extends AndroidViewModel {
 	@Inject
 	ConversationViewModel(Application application,
 			@DatabaseExecutor Executor dbExecutor,
-			@CryptoExecutor Executor cryptoExecutor,
-			MessagingManager messagingManager,
-			ContactManager contactManager,
+			@CryptoExecutor Executor cryptoExecutor, DatabaseComponent db,
+			MessagingManager messagingManager, ContactManager contactManager,
+			SettingsManager settingsManager,
 			PrivateMessageFactory privateMessageFactory) {
 		super(application);
 		this.dbExecutor = dbExecutor;
 		this.cryptoExecutor = cryptoExecutor;
+		this.db = db;
 		this.messagingManager = messagingManager;
 		this.contactManager = contactManager;
+		this.settingsManager = settingsManager;
 		this.privateMessageFactory = privateMessageFactory;
 		this.attachmentController = new AttachmentController(messagingManager,
-				application.getResources());
+				getAttachmentDimensions(application.getResources()));
 		contactDeleted.setValue(false);
 	}
 
+	/**
+	 * Setting the {@link ContactId} automatically triggers loading of other
+	 * data.
+	 */
 	void setContactId(ContactId contactId) {
 		if (this.contactId == null) {
 			this.contactId = contactId;
-			loadContact();
+			loadContact(contactId);
 		} else if (!contactId.equals(this.contactId)) {
 			throw new IllegalStateException();
 		}
 	}
 
-	private void loadContact() {
+	private void loadContact(ContactId contactId) {
 		dbExecutor.execute(() -> {
 			try {
 				long start = now();
-				Contact c =
-						contactManager.getContact(requireNonNull(contactId));
+				Contact c = contactManager.getContact(contactId);
 				contact.postValue(c);
 				logDuration(LOG, "Loading contact", start);
+				start = now();
+				checkFeaturesAndOnboarding(contactId);
+				logDuration(LOG, "Checking for image support", start);
 			} catch (NoSuchContactException e) {
 				contactDeleted.postValue(true);
 			} catch (DbException e) {
@@ -126,7 +155,7 @@ public class ConversationViewModel extends AndroidViewModel {
 			try {
 				contactManager.setContactAlias(requireNonNull(contactId),
 						alias.isEmpty() ? null : alias);
-				loadContact();
+				loadContact(contactId);
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
 			}
@@ -154,6 +183,59 @@ public class ConversationViewModel extends AndroidViewModel {
 		});
 	}
 
+	@DatabaseExecutor
+	private void checkFeaturesAndOnboarding(ContactId c) throws DbException {
+		// check if images are supported
+		boolean imagesSupported = db.transactionWithResult(true, txn ->
+				messagingManager.contactSupportsImages(txn, c));
+		imageSupport.postValue(imagesSupported);
+
+		// check if introductions are supported
+		Collection<Contact> contacts = contactManager.getActiveContacts();
+		boolean introductionSupported = contacts.size() > 1;
+		showIntroductionAction.postValue(introductionSupported);
+
+		Settings settings = settingsManager.getSettings(SETTINGS_NAMESPACE);
+		if (imagesSupported &&
+				settings.getBoolean(SHOW_ONBOARDING_IMAGE, true)) {
+			// check if we should show onboarding, only if images are supported
+			showImageOnboarding.postValue(true);
+			// allow observer to stop listening for changes
+			showIntroductionOnboarding.postValue(false);
+		} else {
+			// allow observer to stop listening for changes
+			showImageOnboarding.postValue(false);
+			// we only show one onboarding dialog at a time
+			if (introductionSupported &&
+					settings.getBoolean(SHOW_ONBOARDING_INTRODUCTION, true)) {
+				showIntroductionOnboarding.postValue(true);
+			} else {
+				// allow observer to stop listening for changes
+				showIntroductionOnboarding.postValue(false);
+			}
+		}
+	}
+
+	void onImageOnboardingSeen() {
+		onOnboardingSeen(SHOW_ONBOARDING_IMAGE);
+	}
+
+	void onIntroductionOnboardingSeen() {
+		onOnboardingSeen(SHOW_ONBOARDING_INTRODUCTION);
+	}
+
+	private void onOnboardingSeen(String key) {
+		dbExecutor.execute(() -> {
+			try {
+				Settings settings = new Settings();
+				settings.putBoolean(key, false);
+				settingsManager.mergeSettings(settings, SETTINGS_NAMESPACE);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
 	private void storeAttachments(GroupId groupId, @Nullable String text,
 			List<Uri> uris, long timestamp) {
 		dbExecutor.execute(() -> {
@@ -262,6 +344,22 @@ public class ConversationViewModel extends AndroidViewModel {
 		return contactName;
 	}
 
+	LiveData<Boolean> hasImageSupport() {
+		return imageSupport;
+	}
+
+	LiveData<Boolean> showImageOnboarding() {
+		return showImageOnboarding;
+	}
+
+	LiveData<Boolean> showIntroductionOnboarding() {
+		return showIntroductionOnboarding;
+	}
+
+	LiveData<Boolean> showIntroductionAction() {
+		return showIntroductionAction;
+	}
+
 	LiveData<Boolean> isContactDeleted() {
 		return contactDeleted;
 	}

briar-android/src/main/java/org/briarproject/briar/android/conversation/ImageActivity.java

@@ -4,15 +4,18 @@ import android.arch.lifecycle.ViewModelProvider;
 import android.arch.lifecycle.ViewModelProviders;
 import android.content.DialogInterface.OnClickListener;
 import android.content.Intent;
-import android.graphics.drawable.Animatable;
 import android.graphics.drawable.Drawable;
 import android.os.Bundle;
 import android.support.annotation.Nullable;
 import android.support.annotation.RequiresApi;
 import android.support.design.widget.AppBarLayout;
 import android.support.design.widget.Snackbar;
+import android.support.v4.app.Fragment;
+import android.support.v4.app.FragmentManager;
+import android.support.v4.app.FragmentStatePagerAdapter;
 import android.support.v4.content.ContextCompat;
 import android.support.v4.graphics.drawable.DrawableCompat;
+import android.support.v4.view.ViewPager;
 import android.support.v7.app.AlertDialog.Builder;
 import android.support.v7.widget.Toolbar;
 import android.transition.Fade;
@@ -20,23 +23,20 @@ import android.transition.Transition;
 import android.view.Menu;
 import android.view.MenuItem;
 import android.view.View;
+import android.view.ViewTreeObserver.OnGlobalLayoutListener;
 import android.view.Window;
 import android.widget.TextView;
 
-import com.bumptech.glide.load.DataSource;
-import com.bumptech.glide.load.engine.GlideException;
-import com.bumptech.glide.request.RequestListener;
-import com.bumptech.glide.request.target.Target;
-import com.github.chrisbanes.photoview.PhotoView;
-
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.activity.BriarActivity;
-import org.briarproject.briar.android.conversation.glide.GlideApp;
 import org.briarproject.briar.android.view.PullDownLayout;
 
 import java.text.SimpleDateFormat;
 import java.util.Date;
+import java.util.List;
 import java.util.Locale;
 
 import javax.inject.Inject;
@@ -53,16 +53,17 @@ import static android.view.View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN;
 import static android.view.View.SYSTEM_UI_FLAG_LAYOUT_STABLE;
 import static android.view.View.VISIBLE;
 import static android.view.WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS;
-import static android.widget.ImageView.ScaleType.FIT_START;
-import static com.bumptech.glide.load.engine.DiskCacheStrategy.NONE;
 import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_SAVE_ATTACHMENT;
 import static org.briarproject.briar.android.util.UiUtils.formatDateAbsolute;
 
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
 public class ImageActivity extends BriarActivity
-		implements PullDownLayout.Callback {
+		implements PullDownLayout.Callback, OnGlobalLayoutListener {
 
-	final static String ATTACHMENT = "attachment";
+	final static String ATTACHMENTS = "attachments";
+	final static String ATTACHMENT_POSITION = "position";
 	final static String NAME = "name";
 	final static String DATE = "date";
 
@@ -72,8 +73,8 @@ public class ImageActivity extends BriarActivity
 	private ImageViewModel viewModel;
 	private PullDownLayout layout;
 	private AppBarLayout appBarLayout;
-	private PhotoView photoView;
-	private AttachmentItem attachment;
+	private ViewPager viewPager;
+	private List<AttachmentItem> attachments;
 
 	@Override
 	public void injectActivity(ActivityComponent component) {
@@ -85,7 +86,7 @@ public class ImageActivity extends BriarActivity
 		super.onCreate(state);
 
 		// Transitions
-		supportPostponeEnterTransition();
+		if (state == null) supportPostponeEnterTransition();
 		Window window = getWindow();
 		if (SDK_INT >= 21) {
 			Transition transition = new Fade();
@@ -100,8 +101,8 @@ public class ImageActivity extends BriarActivity
 		// inflate layout
 		setContentView(R.layout.activity_image);
 		layout = findViewById(R.id.layout);
-		layout.getBackground().setAlpha(255);
 		layout.setCallback(this);
+		layout.getViewTreeObserver().addOnGlobalLayoutListener(this);
 
 		// Status Bar
 		if (SDK_INT >= 21) {
@@ -118,59 +119,29 @@ public class ImageActivity extends BriarActivity
 		TextView dateView = toolbar.findViewById(R.id.dateView);
 
 		// Intent Extras
-		attachment = getIntent().getParcelableExtra(ATTACHMENT);
-		String name = getIntent().getStringExtra(NAME);
-		long time = getIntent().getLongExtra(DATE, 0);
+		Intent i = getIntent();
+		attachments = i.getParcelableArrayListExtra(ATTACHMENTS);
+		int position = i.getIntExtra(ATTACHMENT_POSITION, -1);
+		if (position == -1) throw new IllegalStateException();
+		String name = i.getStringExtra(NAME);
+		long time = i.getLongExtra(DATE, 0);
 		String date = formatDateAbsolute(this, time);
 		contactName.setText(name);
 		dateView.setText(date);
 
-		// Image View
-		photoView = findViewById(R.id.photoView);
+		// Set up image ViewPager
+		viewPager = findViewById(R.id.viewPager);
+		ImagePagerAdapter pagerAdapter =
+				new ImagePagerAdapter(getSupportFragmentManager());
+		viewPager.setAdapter(pagerAdapter);
+		viewPager.setCurrentItem(position);
+
 		if (SDK_INT >= 16) {
-			photoView.setOnClickListener(view -> toggleSystemUi());
+			viewModel.getOnImageClicked().observe(this, this::onImageClicked);
 			window.getDecorView().setSystemUiVisibility(
 					SYSTEM_UI_FLAG_LAYOUT_STABLE |
 							SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN);
 		}
-
-		// Request Listener
-		RequestListener<Drawable> listener = new RequestListener<Drawable>() {
-			@Override
-			public boolean onLoadFailed(@Nullable GlideException e,
-					Object model, Target<Drawable> target,
-					boolean isFirstResource) {
-				supportStartPostponedEnterTransition();
-				return false;
-			}
-
-			@Override
-			public boolean onResourceReady(Drawable resource, Object model,
-					Target<Drawable> target, DataSource dataSource,
-					boolean isFirstResource) {
-				if (SDK_INT >= 21 && !(resource instanceof Animatable)) {
-					// set transition name only when not animatable,
-					// because the animation won't start otherwise
-					photoView.setTransitionName(
-							attachment.getTransitionName());
-				}
-				// Move image to the top if overlapping toolbar
-				if (isOverlappingToolbar(resource)) {
-					photoView.setScaleType(FIT_START);
-				}
-				supportStartPostponedEnterTransition();
-				return false;
-			}
-		};
-
-		// Load Image
-		GlideApp.with(this)
-				.load(attachment)
-				.diskCacheStrategy(NONE)
-				.error(R.drawable.ic_image_broken)
-				.dontTransform()
-				.addListener(listener)
-				.into(photoView);
 	}
 
 	@Override
@@ -194,10 +165,24 @@ public class ImageActivity extends BriarActivity
 	}
 
 	@Override
-	protected void onActivityResult(int request, int result, Intent data) {
+	public void onGlobalLayout() {
+		viewModel.setToolbarPosition(
+				appBarLayout.getTop(), appBarLayout.getBottom()
+		);
+		if (SDK_INT >= 16) {
+			layout.getViewTreeObserver().removeOnGlobalLayoutListener(this);
+		} else {
+			layout.getViewTreeObserver().removeGlobalOnLayoutListener(this);
+		}
+	}
+
+	@Override
+	protected void onActivityResult(int request, int result,
+			@Nullable Intent data) {
 		super.onActivityResult(request, result, data);
-		if (request == REQUEST_SAVE_ATTACHMENT && result == RESULT_OK) {
-			viewModel.saveImage(attachment, data.getData());
+		if (request == REQUEST_SAVE_ATTACHMENT && result == RESULT_OK &&
+				data != null) {
+			viewModel.saveImage(getVisibleAttachment(), data.getData());
 		}
 	}
 
@@ -210,7 +195,6 @@ public class ImageActivity extends BriarActivity
 
 	@Override
 	public void onPull(float progress) {
-		layout.getBackground().setAlpha(Math.round((1 - progress) * 255));
 	}
 
 	@Override
@@ -225,6 +209,14 @@ public class ImageActivity extends BriarActivity
 		supportFinishAfterTransition();
 	}
 
+	@RequiresApi(api = 16)
+	private void onImageClicked(@Nullable Boolean clicked) {
+		if (clicked != null && clicked) {
+			toggleSystemUi();
+			viewModel.onOnImageClickSeen();
+		}
+	}
+
 	@RequiresApi(api = 16)
 	private void toggleSystemUi() {
 		View decorView = getWindow().getDecorView();
@@ -259,29 +251,13 @@ public class ImageActivity extends BriarActivity
 				.start();
 	}
 
-	private boolean isOverlappingToolbar(Drawable drawable) {
-		int width = drawable.getIntrinsicWidth();
-		int height = drawable.getIntrinsicHeight();
-		float widthPercentage = photoView.getWidth() / (float) width;
-		float heightPercentage = photoView.getHeight() / (float) height;
-		float scaleFactor = Math.min(widthPercentage, heightPercentage);
-		int realWidth = (int) (width * scaleFactor);
-		int realHeight = (int) (height * scaleFactor);
-		// return if photo doesn't use the full width,
-		// because it will be moved to the right otherwise
-		if (realWidth < photoView.getWidth()) return false;
-		int drawableTop = (photoView.getHeight() - realHeight) / 2;
-		return drawableTop < appBarLayout.getBottom() &&
-				drawableTop != appBarLayout.getTop();
-	}
-
 	private void showSaveImageDialog() {
 		OnClickListener okListener = (dialog, which) -> {
 			if (SDK_INT >= 19) {
 				Intent intent = getCreationIntent();
 				startActivityForResult(intent, REQUEST_SAVE_ATTACHMENT);
 			} else {
-				viewModel.saveImage(attachment);
+				viewModel.saveImage(getVisibleAttachment());
 			}
 		};
 		Builder builder = new Builder(this, R.style.BriarDialogTheme);
@@ -303,7 +279,7 @@ public class ImageActivity extends BriarActivity
 		String fileName = sdf.format(new Date());
 		Intent intent = new Intent(ACTION_CREATE_DOCUMENT);
 		intent.addCategory(CATEGORY_OPENABLE);
-		intent.setType(attachment.getMimeType());
+		intent.setType(getVisibleAttachment().getMimeType());
 		intent.putExtra(EXTRA_TITLE, fileName);
 		return intent;
 	}
@@ -320,4 +296,31 @@ public class ImageActivity extends BriarActivity
 		viewModel.onSaveStateSeen();
 	}
 
+	AttachmentItem getVisibleAttachment() {
+		return attachments.get(viewPager.getCurrentItem());
+	}
+
+	private class ImagePagerAdapter extends FragmentStatePagerAdapter {
+
+		private boolean isFirst = true;
+
+		private ImagePagerAdapter(FragmentManager fm) {
+			super(fm);
+		}
+
+		@Override
+		public Fragment getItem(int position) {
+			Fragment f = ImageFragment
+					.newInstance(attachments.get(position), isFirst);
+			isFirst = false;
+			return f;
+		}
+
+		@Override
+		public int getCount() {
+			return attachments.size();
+		}
+
+	}
+
 }

briar-android/src/main/java/org/briarproject/briar/android/conversation/ImageFragment.java

@@ -0,0 +1,133 @@
+package org.briarproject.briar.android.conversation;
+
+import android.arch.lifecycle.ViewModelProvider;
+import android.arch.lifecycle.ViewModelProviders;
+import android.graphics.drawable.Animatable;
+import android.graphics.drawable.Drawable;
+import android.os.Bundle;
+import android.support.annotation.Nullable;
+import android.support.v4.app.Fragment;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+
+import com.bumptech.glide.load.DataSource;
+import com.bumptech.glide.load.engine.GlideException;
+import com.bumptech.glide.request.RequestListener;
+import com.bumptech.glide.request.target.Target;
+import com.github.chrisbanes.photoview.PhotoView;
+
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.briar.R;
+import org.briarproject.briar.android.activity.BaseActivity;
+import org.briarproject.briar.android.conversation.glide.GlideApp;
+
+import javax.annotation.ParametersAreNonnullByDefault;
+import javax.inject.Inject;
+
+import static android.os.Build.VERSION.SDK_INT;
+import static android.widget.ImageView.ScaleType.FIT_START;
+import static com.bumptech.glide.load.engine.DiskCacheStrategy.NONE;
+import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
+import static org.briarproject.briar.android.conversation.ImageActivity.ATTACHMENT_POSITION;
+
+@MethodsNotNullByDefault
+@ParametersAreNonnullByDefault
+public class ImageFragment extends Fragment {
+
+	private final static String IS_FIRST = "isFirst";
+
+	@Inject
+	ViewModelProvider.Factory viewModelFactory;
+
+	private AttachmentItem attachment;
+	private boolean isFirst;
+	private ImageViewModel viewModel;
+	private PhotoView photoView;
+
+	static ImageFragment newInstance(AttachmentItem a, boolean isFirst) {
+		ImageFragment f = new ImageFragment();
+		Bundle args = new Bundle();
+		args.putParcelable(ATTACHMENT_POSITION, a);
+		args.putBoolean(IS_FIRST, isFirst);
+		f.setArguments(args);
+		return f;
+	}
+
+	@Override
+	public void onActivityCreated(@Nullable Bundle savedInstanceState) {
+		super.onActivityCreated(savedInstanceState);
+		BaseActivity a = (BaseActivity) requireNonNull(getActivity());
+		a.getActivityComponent().inject(this);
+	}
+
+	@Override
+	public void onCreate(@Nullable Bundle savedInstanceState) {
+		super.onCreate(savedInstanceState);
+
+		Bundle args = requireNonNull(getArguments());
+		attachment = requireNonNull(args.getParcelable(ATTACHMENT_POSITION));
+		isFirst = args.getBoolean(IS_FIRST);
+	}
+
+	@Nullable
+	@Override
+	public View onCreateView(LayoutInflater inflater,
+			@Nullable ViewGroup container,
+			@Nullable Bundle savedInstanceState) {
+		View v = inflater.inflate(R.layout.fragment_image, container,
+				false);
+
+		viewModel = ViewModelProviders.of(requireNonNull(getActivity()),
+				viewModelFactory).get(ImageViewModel.class);
+
+		photoView = v.findViewById(R.id.photoView);
+		photoView.setScaleLevels(1, 2, 4);
+		photoView.setOnClickListener(view -> viewModel.clickImage());
+
+		// Request Listener
+		RequestListener<Drawable> listener = new RequestListener<Drawable>() {
+			@Override
+			public boolean onLoadFailed(@Nullable GlideException e,
+					Object model, Target<Drawable> target,
+					boolean isFirstResource) {
+				if (getActivity() != null && isFirst)
+					getActivity().supportStartPostponedEnterTransition();
+				return false;
+			}
+
+			@Override
+			public boolean onResourceReady(Drawable resource, Object model,
+					Target<Drawable> target, DataSource dataSource,
+					boolean isFirstResource) {
+				if (SDK_INT >= 21 && !(resource instanceof Animatable)) {
+					// set transition name only when not animatable,
+					// because the animation won't start otherwise
+					photoView.setTransitionName(
+							attachment.getTransitionName());
+				}
+				// Move image to the top if overlapping toolbar
+				if (viewModel.isOverlappingToolbar(photoView, resource)) {
+					photoView.setScaleType(FIT_START);
+				}
+				if (getActivity() != null && isFirst) {
+					getActivity().supportStartPostponedEnterTransition();
+				}
+				return false;
+			}
+		};
+
+		// Load Image
+		GlideApp.with(this)
+				.load(attachment)
+				// TODO allow if size < maxTextureSize ?
+//				.override(SIZE_ORIGINAL)
+				.diskCacheStrategy(NONE)
+				.error(R.drawable.ic_image_broken)
+				.addListener(listener)
+				.into(photoView);
+
+		return v;
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/conversation/ImageHelper.java

@@ -0,0 +1,29 @@
+package org.briarproject.briar.android.conversation;
+
+import android.support.annotation.Nullable;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.io.InputStream;
+
+@NotNullByDefault
+interface ImageHelper {
+
+	DecodeResult decodeStream(InputStream is);
+
+	@Nullable
+	String getExtensionFromMimeType(String mimeType);
+
+	class DecodeResult {
+
+		final int width;
+		final int height;
+		final String mimeType;
+
+		DecodeResult(int width, int height, String mimeType) {
+			this.width = width;
+			this.height = height;
+			this.mimeType = mimeType;
+		}
+	}
+}

briar-android/src/main/java/org/briarproject/briar/android/conversation/ImageItemDecoration.java

@@ -10,12 +10,12 @@ import android.view.View;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.util.UiUtils;
 
 import static org.briarproject.briar.android.conversation.ImageAdapter.isBottomRow;
 import static org.briarproject.briar.android.conversation.ImageAdapter.isLeft;
 import static org.briarproject.briar.android.conversation.ImageAdapter.isTopRow;
 import static org.briarproject.briar.android.conversation.ImageAdapter.singleInRow;
+import static org.briarproject.briar.android.util.UiUtils.isRtl;
 
 @NotNullByDefault
 class ImageItemDecoration extends ItemDecoration {
@@ -35,7 +35,7 @@ class ImageItemDecoration extends ItemDecoration {
 		border = realBorderSize / 2;
 
 		// find out if we are showing a RTL language
-		isRtl = UiUtils.isRtl(ctx);
+		isRtl = isRtl(ctx);
 	}
 
 	@Override

briar-android/src/main/java/org/briarproject/briar/android/conversation/ImageViewHolder.java

@@ -15,6 +15,7 @@ import org.briarproject.briar.android.conversation.glide.BriarImageTransformatio
 import org.briarproject.briar.android.conversation.glide.GlideApp;
 import org.briarproject.briar.android.conversation.glide.Radii;
 
+import static android.os.Build.VERSION.SDK_INT;
 import static com.bumptech.glide.load.engine.DiskCacheStrategy.NONE;
 import static com.bumptech.glide.load.resource.drawable.DrawableTransitionOptions.withCrossFade;
 
@@ -42,6 +43,9 @@ class ImageViewHolder extends ViewHolder {
 		} else {
 			setImageViewDimensions(attachment, single, needsStretch);
 			loadImage(attachment, r);
+			if (SDK_INT >= 21) {
+				imageView.setTransitionName(attachment.getTransitionName());
+			}
 		}
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/conversation/ImageViewModel.java

@@ -4,9 +4,11 @@ import android.app.Application;
 import android.arch.lifecycle.AndroidViewModel;
 import android.arch.lifecycle.LiveData;
 import android.arch.lifecycle.MutableLiveData;
+import android.graphics.drawable.Drawable;
 import android.net.Uri;
 import android.support.annotation.Nullable;
 import android.support.annotation.UiThread;
+import android.view.View;
 
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
@@ -48,7 +50,13 @@ public class ImageViewModel extends AndroidViewModel {
 	@IoExecutor
 	private final Executor ioExecutor;
 
+	/**
+	 * true means there was an error saving the image, false if image was saved.
+	 */
 	private final MutableLiveData<Boolean> saveState = new MutableLiveData<>();
+	private final MutableLiveData<Boolean> imageClicked =
+			new MutableLiveData<>();
+	private int toolbarTop, toolbarBottom;
 
 	@Inject
 	ImageViewModel(Application application,
@@ -61,9 +69,49 @@ public class ImageViewModel extends AndroidViewModel {
 		this.ioExecutor = ioExecutor;
 	}
 
+	void clickImage() {
+		imageClicked.setValue(true);
+	}
+
 	/**
-	 * A LiveData that is true if the image was saved,
-	 * false if there was an error and null otherwise.
+	 * A LiveData that is true if the image was clicked,
+	 * false if it wasn't.
+	 *
+	 * Call {@link #onOnImageClickSeen()} after consuming an update.
+	 */
+	LiveData<Boolean> getOnImageClicked() {
+		return imageClicked;
+	}
+
+	@UiThread
+	void onOnImageClickSeen() {
+		imageClicked.setValue(false);
+	}
+
+	void setToolbarPosition(int top, int bottom) {
+		toolbarTop = top;
+		toolbarBottom = bottom;
+	}
+
+	boolean isOverlappingToolbar(View screenView, Drawable drawable) {
+		int width = drawable.getIntrinsicWidth();
+		int height = drawable.getIntrinsicHeight();
+		float widthPercentage = screenView.getWidth() / (float) width;
+		float heightPercentage = screenView.getHeight() / (float) height;
+		float scaleFactor = Math.min(widthPercentage, heightPercentage);
+		int realWidth = (int) (width * scaleFactor);
+		int realHeight = (int) (height * scaleFactor);
+		// return if image doesn't use the full width,
+		// because it will be moved to the right otherwise
+		if (realWidth < screenView.getWidth()) return false;
+		int drawableTop = (screenView.getHeight() - realHeight) / 2;
+		return drawableTop < toolbarBottom && drawableTop != toolbarTop;
+	}
+
+	/**
+	 * A LiveData that is true if there was an error
+	 * and false if the image was saved.
+	 * It can be null otherwise, if no image was saved recently.
 	 *
 	 * Call {@link #onSaveStateSeen()} after consuming an update.
 	 */
@@ -82,7 +130,7 @@ public class ImageViewModel extends AndroidViewModel {
 	@UiThread
 	void saveImage(AttachmentItem attachment, @Nullable Uri uri) {
 		if (uri == null) {
-			saveState.setValue(false);
+			saveState.setValue(true);
 		} else {
 			saveImage(attachment, () -> getOutputStream(uri), null);
 		}

briar-android/src/main/java/org/briarproject/briar/android/conversation/glide/BriarDataFetcher.java

@@ -40,7 +40,7 @@ class BriarDataFetcher implements DataFetcher<InputStream> {
 	private volatile boolean cancel = false;
 
 	@Inject
-	public BriarDataFetcher(MessagingManager messagingManager,
+	BriarDataFetcher(MessagingManager messagingManager,
 			@DatabaseExecutor Executor dbExecutor, AttachmentItem attachment) {
 		this.messagingManager = messagingManager;
 		this.dbExecutor = dbExecutor;

briar-android/src/main/java/org/briarproject/briar/android/conversation/glide/BriarModelLoader.java

@@ -22,7 +22,7 @@ public final class BriarModelLoader
 	@Inject
 	BriarDataFetcherFactory dataFetcherFactory;
 
-	public BriarModelLoader(BriarApplication app) {
+	BriarModelLoader(BriarApplication app) {
 		app.getApplicationComponent().inject(this);
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/conversation/glide/BriarModelLoaderFactory.java

@@ -16,7 +16,7 @@ class BriarModelLoaderFactory
 
 	private final BriarApplication app;
 
-	public BriarModelLoaderFactory(BriarApplication app) {
+	BriarModelLoaderFactory(BriarApplication app) {
 		this.app = app;
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/conversation/glide/CustomCornersTransformation.java

@@ -21,13 +21,14 @@ import static android.graphics.Shader.TileMode.CLAMP;
 
 @Immutable
 @NotNullByDefault
-public class CustomCornersTransformation extends BitmapTransformation {
+class CustomCornersTransformation extends BitmapTransformation {
 
-	private static final String ID = CustomCornersTransformation.class.getName();
+	private static final String ID =
+			CustomCornersTransformation.class.getName();
 
 	private final Radii radii;
 
-	public CustomCornersTransformation(Radii radii) {
+	CustomCornersTransformation(Radii radii) {
 		this.radii = radii;
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumListFragment.java

@@ -44,6 +44,7 @@ import javax.annotation.Nullable;
 import javax.inject.Inject;
 
 import static android.support.design.widget.Snackbar.LENGTH_INDEFINITE;
+import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.logException;
@@ -80,13 +81,18 @@ public class ForumListFragment extends BaseEventFragment implements
 		return fragment;
 	}
 
+	@Override
+	public void injectFragment(ActivityComponent component) {
+		component.inject(this);
+	}
+
 	@Nullable
 	@Override
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
 
-		getActivity().setTitle(R.string.forums_button);
+		requireNonNull(getActivity()).setTitle(R.string.forums_button);
 
 		View contentView =
 				inflater.inflate(R.layout.fragment_forum_list, container,
@@ -102,7 +108,7 @@ public class ForumListFragment extends BaseEventFragment implements
 		snackbar.getView().setBackgroundResource(R.color.briar_primary);
 		snackbar.setAction(R.string.show, this);
 		snackbar.setActionTextColor(ContextCompat
-				.getColor(getContext(), R.color.briar_button_text_positive));
+				.getColor(getActivity(), R.color.briar_button_text_positive));
 
 		return contentView;
 	}
@@ -112,11 +118,6 @@ public class ForumListFragment extends BaseEventFragment implements
 		return TAG;
 	}
 
-	@Override
-	public void injectFragment(ActivityComponent component) {
-		component.inject(this);
-	}
-
 	@Override
 	public void onStart() {
 		super.onStart();

briar-android/src/main/java/org/briarproject/briar/android/fragment/BaseFragment.java

@@ -10,11 +10,15 @@ import android.support.v4.app.FragmentActivity;
 import android.view.MenuItem;
 
 import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.android.DestroyableContext;
 import org.briarproject.briar.android.activity.ActivityComponent;
 
 import javax.annotation.Nullable;
 
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
 public abstract class BaseFragment extends Fragment
 		implements DestroyableContext {
 
@@ -22,12 +26,15 @@ public abstract class BaseFragment extends Fragment
 
 	public abstract String getUniqueTag();
 
-	public abstract void injectFragment(ActivityComponent component);
-
 	@Override
 	public void onAttach(Context context) {
 		super.onAttach(context);
 		listener = (BaseFragmentListener) context;
+		injectFragment(listener.getActivityComponent());
+	}
+
+	public void injectFragment(ActivityComponent component) {
+		// fragments that need to inject, can override this method
 	}
 
 	@Override
@@ -38,12 +45,6 @@ public abstract class BaseFragment extends Fragment
 		setHasOptionsMenu(true);
 	}
 
-	@Override
-	public void onActivityCreated(@Nullable Bundle savedInstanceState) {
-		super.onActivityCreated(savedInstanceState);
-		injectFragment(listener.getActivityComponent());
-	}
-
 	@Override
 	public boolean onOptionsItemSelected(MenuItem item) {
 		switch (item.getItemId()) {

briar-android/src/main/java/org/briarproject/briar/android/fragment/ErrorFragment.java

@@ -10,7 +10,6 @@ import android.widget.TextView;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.activity.ActivityComponent;
 
 
 @MethodsNotNullByDefault
@@ -57,9 +56,4 @@ public class ErrorFragment extends BaseFragment {
 		return v;
 	}
 
-	@Override
-	public void injectFragment(ActivityComponent component) {
-		// not necessary
-	}
-
 }

briar-android/src/main/java/org/briarproject/briar/android/introduction/ContactChooserFragment.java

@@ -1,7 +1,8 @@
 package org.briarproject.briar.android.introduction;
 
-import android.content.Context;
 import android.os.Bundle;
+import android.support.annotation.Nullable;
+import android.support.annotation.UiThread;
 import android.support.v7.widget.LinearLayoutManager;
 import android.view.LayoutInflater;
 import android.view.View;
@@ -11,6 +12,8 @@ import org.briarproject.bramble.api.contact.Contact;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.contact.ContactManager;
 import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.plugin.ConnectionRegistry;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
@@ -28,10 +31,14 @@ import java.util.logging.Logger;
 
 import javax.inject.Inject;
 
+import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.briar.android.conversation.ConversationActivity.CONTACT_ID;
 
+@UiThread
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
 public class ContactChooserFragment extends BaseFragment {
 
 	public static final String TAG = ContactChooserFragment.class.getName();
@@ -51,7 +58,6 @@ public class ContactChooserFragment extends BaseFragment {
 	volatile ConnectionRegistry connectionRegistry;
 
 	public static ContactChooserFragment newInstance(ContactId id) {
-
 		Bundle args = new Bundle();
 
 		ContactChooserFragment fragment = new ContactChooserFragment();
@@ -61,13 +67,13 @@ public class ContactChooserFragment extends BaseFragment {
 	}
 
 	@Override
-	public void onAttach(Context context) {
-		super.onAttach(context);
+	public void injectFragment(ActivityComponent component) {
+		component.inject(this);
 	}
 
 	@Override
-	public View onCreateView(LayoutInflater inflater, ViewGroup container,
-			Bundle savedInstanceState) {
+	public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container,
+			@Nullable Bundle savedInstanceState) {
 
 		View contentView = inflater.inflate(R.layout.list, container, false);
 
@@ -77,14 +83,16 @@ public class ContactChooserFragment extends BaseFragment {
 					Contact c2 = item.getContact();
 					showMessageScreen(c1, c2);
 				};
-		adapter = new ContactListAdapter(getActivity(), onContactClickListener);
+		adapter = new ContactListAdapter(requireNonNull(getActivity()),
+				onContactClickListener);
 
 		list = contentView.findViewById(R.id.list);
 		list.setLayoutManager(new LinearLayoutManager(getActivity()));
 		list.setAdapter(adapter);
 		list.setEmptyText(R.string.no_contacts);
 
-		contactId = new ContactId(getArguments().getInt(CONTACT_ID));
+		contactId = new ContactId(
+				requireNonNull(getArguments()).getInt(CONTACT_ID));
 
 		return contentView;
 	}
@@ -107,11 +115,6 @@ public class ContactChooserFragment extends BaseFragment {
 		return TAG;
 	}
 
-	@Override
-	public void injectFragment(ActivityComponent component) {
-		component.inject(this);
-	}
-
 	private void loadContacts() {
 		listener.runOnDbThread(() -> {
 			try {

briar-android/src/main/java/org/briarproject/briar/android/introduction/IntroductionMessageFragment.java

@@ -39,6 +39,7 @@ import static android.app.Activity.RESULT_OK;
 import static android.view.View.GONE;
 import static android.view.View.VISIBLE;
 import static android.widget.Toast.LENGTH_SHORT;
+import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.briar.android.util.UiUtils.getContactDisplayName;
@@ -77,17 +78,17 @@ public class IntroductionMessageFragment extends BaseFragment
 		return fragment;
 	}
 
-	@Override
-	public void injectFragment(ActivityComponent component) {
-		component.inject(this);
-	}
-
 	@Override
 	public void onAttach(Context context) {
 		super.onAttach(context);
 		introductionActivity = (IntroductionActivity) context;
 	}
 
+	@Override
+	public void injectFragment(ActivityComponent component) {
+		component.inject(this);
+	}
+
 	@Override
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
@@ -99,6 +100,14 @@ public class IntroductionMessageFragment extends BaseFragment
 			actionBar.setTitle(R.string.introduction_message_title);
 		}
 
+		// get contact IDs from fragment arguments
+		Bundle args = requireNonNull(getArguments());
+		int contactId1 = args.getInt(CONTACT_ID_1, -1);
+		int contactId2 = args.getInt(CONTACT_ID_2, -1);
+		if (contactId1 == -1 || contactId2 == -1) {
+			throw new AssertionError("Use newInstance() to instantiate");
+		}
+
 		// inflate view
 		View v = inflater.inflate(R.layout.introduction_message, container,
 				false);
@@ -109,22 +118,15 @@ public class IntroductionMessageFragment extends BaseFragment
 		ui.message.setMaxTextLength(MAX_INTRODUCTION_TEXT_LENGTH);
 		ui.message.setEnabled(false);
 
+		// get contacts and then show view
+		prepareToSetUpViews(contactId1, contactId2);
+
 		return v;
 	}
 
 	@Override
 	public void onStart() {
 		super.onStart();
-
-		// get contact IDs from fragment arguments
-		int contactId1 = getArguments().getInt(CONTACT_ID_1, -1);
-		int contactId2 = getArguments().getInt(CONTACT_ID_2, -1);
-		if (contactId1 == -1 || contactId2 == -1) {
-			throw new java.lang.InstantiationError(
-					"You need to use newInstance() to instantiate");
-		}
-		// get contacts and then show view
-		prepareToSetUpViews(contactId1, contactId2);
 	}
 
 	@Override

briar-android/src/main/java/org/briarproject/briar/android/keyagreement/ContactExchangeErrorFragment.java

@@ -44,6 +44,11 @@ public class ContactExchangeErrorFragment extends BaseFragment {
 		return TAG;
 	}
 
+	@Override
+	public void injectFragment(ActivityComponent component) {
+		component.inject(this);
+	}
+
 	@Nullable
 	@Override
 	public View onCreateView(LayoutInflater inflater,
@@ -74,11 +79,6 @@ public class ContactExchangeErrorFragment extends BaseFragment {
 		return v;
 	}
 
-	@Override
-	public void injectFragment(ActivityComponent component) {
-		component.inject(this);
-	}
-
 	private void triggerFeedback() {
 		finish();
 		UiUtils.triggerFeedback(androidExecutor);

briar-android/src/main/java/org/briarproject/briar/android/keyagreement/IntroFragment.java

@@ -10,7 +10,6 @@ import android.widget.ScrollView;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.fragment.BaseFragment;
 
 import javax.annotation.Nullable;
@@ -39,11 +38,6 @@ public class IntroFragment extends BaseFragment {
 		return fragment;
 	}
 
-	@Override
-	public void injectFragment(ActivityComponent component) {
-		component.inject(this);
-	}
-
 	@Override
 	public void onAttach(Context context) {
 		super.onAttach(context);

briar-android/src/main/java/org/briarproject/briar/android/keyagreement/KeyAgreementFragment.java

@@ -53,6 +53,7 @@ import static android.view.View.VISIBLE;
 import static android.view.ViewGroup.LayoutParams.MATCH_PARENT;
 import static android.widget.LinearLayout.HORIZONTAL;
 import static android.widget.Toast.LENGTH_LONG;
+import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.util.LogUtils.logException;
@@ -136,7 +137,8 @@ public class KeyAgreementFragment extends BaseEventFragment
 	@Override
 	public void onActivityCreated(@Nullable Bundle savedInstanceState) {
 		super.onActivityCreated(savedInstanceState);
-		getActivity().setRequestedOrientation(SCREEN_ORIENTATION_NOSENSOR);
+		requireNonNull(getActivity())
+				.setRequestedOrientation(SCREEN_ORIENTATION_NOSENSOR);
 		cameraView.setPreviewConsumer(new QrCodeDecoder(this));
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/login/AuthorNameFragment.java

@@ -18,6 +18,7 @@ import javax.annotation.Nullable;
 
 import static android.view.inputmethod.EditorInfo.IME_ACTION_NEXT;
 import static android.view.inputmethod.EditorInfo.IME_ACTION_NONE;
+import static java.util.Objects.requireNonNull;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_AUTHOR_NAME_LENGTH;
 import static org.briarproject.briar.android.util.UiUtils.setError;
 
@@ -35,11 +36,16 @@ public class AuthorNameFragment extends SetupFragment {
 		return new AuthorNameFragment();
 	}
 
+	@Override
+	public void injectFragment(ActivityComponent component) {
+		component.inject(this);
+	}
+
 	@Override
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-		getActivity().setTitle(getString(R.string.setup_title));
+		requireNonNull(getActivity()).setTitle(getString(R.string.setup_title));
 		View v = inflater.inflate(R.layout.fragment_setup_author_name,
 				container, false);
 		authorNameWrapper = v.findViewById(R.id.nickname_entry_wrapper);
@@ -57,11 +63,6 @@ public class AuthorNameFragment extends SetupFragment {
 		return TAG;
 	}
 
-	@Override
-	public void injectFragment(ActivityComponent component) {
-		component.inject(this);
-	}
-
 	@Override
 	protected String getHelpText() {
 		return getString(R.string.setup_name_explanation);

briar-android/src/main/java/org/briarproject/briar/android/login/DozeFragment.java

@@ -19,6 +19,7 @@ import org.briarproject.briar.android.util.UiUtils;
 
 import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
+import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_DOZE_WHITELISTING;
 import static org.briarproject.briar.android.util.UiUtils.showOnboardingDialog;
 
@@ -39,11 +40,16 @@ public class DozeFragment extends SetupFragment
 		return new DozeFragment();
 	}
 
+	@Override
+	public void injectFragment(ActivityComponent component) {
+		component.inject(this);
+	}
+
 	@Override
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-		getActivity().setTitle(getString(R.string.setup_doze_title));
+		requireNonNull(getActivity()).setTitle(getString(R.string.setup_doze_title));
 		setHasOptionsMenu(false);
 		View v = inflater.inflate(R.layout.fragment_setup_doze, container,
 						false);
@@ -65,11 +71,6 @@ public class DozeFragment extends SetupFragment
 		return TAG;
 	}
 
-	@Override
-	public void injectFragment(ActivityComponent component) {
-		component.inject(this);
-	}
-
 	@Override
 	protected String getHelpText() {
 		return getString(R.string.setup_doze_explanation);

briar-android/src/main/java/org/briarproject/briar/android/login/PasswordFragment.java

@@ -23,6 +23,7 @@ import static android.content.Context.INPUT_METHOD_SERVICE;
 import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
 import static android.view.inputmethod.EditorInfo.IME_ACTION_DONE;
+import static java.util.Objects.requireNonNull;
 import static org.briarproject.bramble.api.crypto.PasswordStrengthEstimator.QUITE_WEAK;
 
 @MethodsNotNullByDefault
@@ -43,11 +44,16 @@ public class PasswordFragment extends SetupFragment {
 		return new PasswordFragment();
 	}
 
+	@Override
+	public void injectFragment(ActivityComponent component) {
+		component.inject(this);
+	}
+
 	@Override
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-		getActivity().setTitle(getString(R.string.setup_password_intro));
+		requireNonNull(getActivity()).setTitle(getString(R.string.setup_password_intro));
 		View v = inflater.inflate(R.layout.fragment_setup_password, container,
 						false);
 
@@ -64,6 +70,11 @@ public class PasswordFragment extends SetupFragment {
 		passwordConfirmation.addTextChangedListener(this);
 		nextButton.setOnClickListener(this);
 
+		if (!setupController.needToShowDozeFragment()) {
+			nextButton.setText(R.string.create_account_button);
+			passwordConfirmation.setImeOptions(IME_ACTION_DONE);
+		}
+
 		return v;
 	}
 
@@ -72,17 +83,6 @@ public class PasswordFragment extends SetupFragment {
 		return TAG;
 	}
 
-	@Override
-	public void injectFragment(ActivityComponent component) {
-		component.inject(this);
-
-		// the controller is not yet available in onCreateView()
-		if (!setupController.needToShowDozeFragment()) {
-			nextButton.setText(R.string.create_account_button);
-			passwordConfirmation.setImeOptions(IME_ACTION_DONE);
-		}
-	}
-
 	@Override
 	protected String getHelpText() {
 		return getString(R.string.setup_password_explanation);

briar-android/src/main/java/org/briarproject/briar/android/login/SetupFragment.java

@@ -11,7 +11,8 @@ import android.view.View.OnClickListener;
 import android.widget.TextView;
 import android.widget.TextView.OnEditorActionListener;
 
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.fragment.BaseFragment;
 
@@ -22,7 +23,8 @@ import static android.view.inputmethod.EditorInfo.IME_ACTION_NEXT;
 import static org.briarproject.briar.android.util.UiUtils.enterPressed;
 import static org.briarproject.briar.android.util.UiUtils.showOnboardingDialog;
 
-@NotNullByDefault
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
 abstract class SetupFragment extends BaseFragment implements TextWatcher,
 		OnEditorActionListener, OnClickListener {
 

briar-android/src/main/java/org/briarproject/briar/android/logout/ExitActivity.java

@@ -1,14 +1,13 @@
 package org.briarproject.briar.android.logout;
 
-import android.os.Build;
+import android.app.Activity;
 import android.os.Bundle;
 
-import org.briarproject.briar.android.activity.ActivityComponent;
-import org.briarproject.briar.android.activity.BaseActivity;
-
 import java.util.logging.Logger;
 
-public class ExitActivity extends BaseActivity {
+import static android.os.Build.VERSION.SDK_INT;
+
+public class ExitActivity extends Activity {
 
 	private static final Logger LOG =
 			Logger.getLogger(ExitActivity.class.getName());
@@ -16,14 +15,9 @@ public class ExitActivity extends BaseActivity {
 	@Override
 	public void onCreate(Bundle state) {
 		super.onCreate(state);
-		if (Build.VERSION.SDK_INT >= 21) finishAndRemoveTask();
+		if (SDK_INT >= 21) finishAndRemoveTask();
 		else finish();
 		LOG.info("Exiting");
 		System.exit(0);
 	}
-
-	@Override
-	public void injectActivity(ActivityComponent component) {
-
-	}
 }

briar-android/src/main/java/org/briarproject/briar/android/logout/HideUiActivity.java

@@ -1,20 +1,13 @@
 package org.briarproject.briar.android.logout;
 
+import android.app.Activity;
 import android.os.Bundle;
 
-import org.briarproject.briar.android.activity.ActivityComponent;
-import org.briarproject.briar.android.activity.BaseActivity;
-
-public class HideUiActivity extends BaseActivity {
+public class HideUiActivity extends Activity {
 
 	@Override
 	public void onCreate(Bundle state) {
 		super.onCreate(state);
 		finish();
 	}
-
-	@Override
-	public void injectActivity(ActivityComponent component) {
-
-	}
 }

briar-android/src/main/java/org/briarproject/briar/android/logout/SignOutFragment.java

@@ -5,19 +5,21 @@ import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.fragment.BaseFragment;
 
-import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
 public class SignOutFragment extends BaseFragment {
 
 	public static final String TAG = SignOutFragment.class.getName();
 
 	@Override
-	public View onCreateView(@Nonnull LayoutInflater inflater,
+	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
 		return inflater.inflate(R.layout.fragment_sign_out, container, false);
@@ -27,9 +29,4 @@ public class SignOutFragment extends BaseFragment {
 	public String getUniqueTag() {
 		return TAG;
 	}
-
-	@Override
-	public void injectFragment(ActivityComponent component) {
-		// no need to inject
-	}
 }

briar-android/src/main/java/org/briarproject/briar/android/navdrawer/NavDrawerActivity.java

@@ -5,6 +5,7 @@ import android.content.Intent;
 import android.content.res.Configuration;
 import android.os.Bundle;
 import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 import android.support.design.widget.NavigationView;
 import android.support.design.widget.NavigationView.OnNavigationItemSelectedListener;
 import android.support.v4.app.ActivityCompat;
@@ -12,6 +13,7 @@ import android.support.v4.app.FragmentManager;
 import android.support.v4.app.FragmentTransaction;
 import android.support.v4.content.ContextCompat;
 import android.support.v4.widget.DrawerLayout;
+import android.support.v7.app.ActionBar;
 import android.support.v7.app.ActionBarDrawerToggle;
 import android.support.v7.widget.Toolbar;
 import android.view.LayoutInflater;
@@ -25,6 +27,8 @@ import android.widget.TextView;
 
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.plugin.BluetoothConstants;
 import org.briarproject.bramble.api.plugin.LanTcpConstants;
 import org.briarproject.bramble.api.plugin.TorConstants;
@@ -54,6 +58,7 @@ import static android.support.v4.view.GravityCompat.START;
 import static android.support.v4.widget.DrawerLayout.LOCK_MODE_LOCKED_CLOSED;
 import static android.view.View.GONE;
 import static android.view.View.VISIBLE;
+import static java.util.Objects.requireNonNull;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.RUNNING;
 import static org.briarproject.briar.android.BriarService.EXTRA_STARTUP_FAILED;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_PASSWORD;
@@ -61,6 +66,8 @@ import static org.briarproject.briar.android.navdrawer.NavDrawerController.Expir
 import static org.briarproject.briar.android.navdrawer.NavDrawerController.ExpiryWarning.UPDATE;
 import static org.briarproject.briar.android.util.UiUtils.getDaysUntilExpiry;
 
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
 public class NavDrawerActivity extends BriarActivity implements
 		BaseFragmentListener, TransportStateListener,
 		OnNavigationItemSelectedListener {
@@ -112,9 +119,8 @@ public class NavDrawerActivity extends BriarActivity implements
 		component.inject(this);
 	}
 
-	@SuppressWarnings("ConstantConditions")
 	@Override
-	public void onCreate(Bundle state) {
+	public void onCreate(@Nullable Bundle state) {
 		super.onCreate(state);
 		exitIfStartupFailed(getIntent());
 		setContentView(R.layout.activity_nav_drawer);
@@ -125,8 +131,9 @@ public class NavDrawerActivity extends BriarActivity implements
 		GridView transportsView = findViewById(R.id.transportsView);
 
 		setSupportActionBar(toolbar);
-		getSupportActionBar().setDisplayHomeAsUpEnabled(true);
-		getSupportActionBar().setHomeButtonEnabled(true);
+		ActionBar actionBar = requireNonNull(getSupportActionBar());
+		actionBar.setDisplayHomeAsUpEnabled(true);
+		actionBar.setHomeButtonEnabled(true);
 
 		drawerToggle = new ActionBarDrawerToggle(this, drawerLayout, toolbar,
 				R.string.nav_drawer_open_description,
@@ -165,7 +172,8 @@ public class NavDrawerActivity extends BriarActivity implements
 	}
 
 	@Override
-	protected void onActivityResult(int request, int result, Intent data) {
+	protected void onActivityResult(int request, int result,
+			@Nullable Intent data) {
 		super.onActivityResult(request, result, data);
 		if (request == REQUEST_PASSWORD && result == RESULT_OK) {
 			controller.shouldAskForDozeWhitelisting(this,
@@ -253,7 +261,7 @@ public class NavDrawerActivity extends BriarActivity implements
 	}
 
 	@Override
-	public void onPostCreate(Bundle savedInstanceState) {
+	public void onPostCreate(@Nullable Bundle savedInstanceState) {
 		super.onPostCreate(savedInstanceState);
 		drawerToggle.syncState();
 	}

briar-android/src/main/java/org/briarproject/briar/android/panic/PanicResponderActivity.java

@@ -2,7 +2,6 @@ package org.briarproject.briar.android.panic;
 
 import android.content.Intent;
 import android.content.SharedPreferences;
-import android.os.Build;
 import android.os.Bundle;
 import android.support.v7.preference.PreferenceManager;
 
@@ -20,6 +19,7 @@ import info.guardianproject.panic.Panic;
 import info.guardianproject.panic.PanicResponder;
 import info.guardianproject.trustedintents.TrustedIntents;
 
+import static android.os.Build.VERSION.SDK_INT;
 import static org.briarproject.briar.android.panic.PanicPreferencesFragment.KEY_LOCK;
 import static org.briarproject.briar.android.panic.PanicPreferencesFragment.KEY_PURGE;
 
@@ -69,7 +69,7 @@ public class PanicResponderActivity extends BriarActivity {
 			}
 		}
 
-		if (Build.VERSION.SDK_INT >= 21) {
+		if (SDK_INT >= 21) {
 			finishAndRemoveTask();
 		} else {
 			finish();

briar-android/src/main/java/org/briarproject/briar/android/privategroup/creation/CreateGroupFragment.java

@@ -2,6 +2,7 @@ package org.briarproject.briar.android.privategroup.creation;
 
 import android.content.Context;
 import android.os.Bundle;
+import android.support.annotation.Nullable;
 import android.support.design.widget.TextInputLayout;
 import android.text.Editable;
 import android.text.TextWatcher;
@@ -12,6 +13,8 @@ import android.widget.Button;
 import android.widget.EditText;
 import android.widget.ProgressBar;
 
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.util.StringUtils;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
@@ -23,6 +26,8 @@ import static android.view.inputmethod.EditorInfo.IME_ACTION_DONE;
 import static org.briarproject.briar.android.util.UiUtils.enterPressed;
 import static org.briarproject.briar.api.privategroup.PrivateGroupConstants.MAX_GROUP_NAME_LENGTH;
 
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
 public class CreateGroupFragment extends BaseFragment {
 
 	public final static String TAG = CreateGroupFragment.class.getName();
@@ -40,8 +45,13 @@ public class CreateGroupFragment extends BaseFragment {
 	}
 
 	@Override
-	public View onCreateView(LayoutInflater inflater, ViewGroup container,
-			Bundle savedInstanceState) {
+	public void injectFragment(ActivityComponent component) {
+		component.inject(this);
+	}
+
+	@Override
+	public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container,
+			@Nullable Bundle savedInstanceState) {
 
 		View v = inflater.inflate(R.layout.fragment_create_group, container,
 				false);
@@ -87,11 +97,6 @@ public class CreateGroupFragment extends BaseFragment {
 		listener.showSoftKeyboard(nameEntry);
 	}
 
-	@Override
-	public void injectFragment(ActivityComponent component) {
-		component.inject(this);
-	}
-
 	@Override
 	public String getUniqueTag() {
 		return TAG;

briar-android/src/main/java/org/briarproject/briar/android/privategroup/creation/CreateGroupMessageFragment.java

@@ -2,10 +2,13 @@ package org.briarproject.briar.android.privategroup.creation;
 
 import android.support.annotation.StringRes;
 
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.sharing.BaseMessageFragment;
 
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
 public class CreateGroupMessageFragment extends BaseMessageFragment {
 
 	private final static String TAG =
@@ -28,9 +31,4 @@ public class CreateGroupMessageFragment extends BaseMessageFragment {
 		return TAG;
 	}
 
-	@Override
-	public void injectFragment(ActivityComponent component) {
-		component.inject(this);
-	}
-
 }

briar-android/src/main/java/org/briarproject/briar/android/privategroup/creation/GroupInviteFragment.java

@@ -1,6 +1,7 @@
 package org.briarproject.briar.android.privategroup.creation;
 
 import android.os.Bundle;
+import android.support.annotation.Nullable;
 
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
@@ -13,6 +14,7 @@ import org.briarproject.briar.android.contactselection.SelectableContactItem;
 
 import javax.inject.Inject;
 
+import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
 
 @MethodsNotNullByDefault
@@ -33,14 +35,14 @@ public class GroupInviteFragment extends ContactSelectorFragment {
 	}
 
 	@Override
-	public void onCreate(Bundle savedInstanceState) {
-		super.onCreate(savedInstanceState);
-		getActivity().setTitle(R.string.groups_invite_members);
+	public void injectFragment(ActivityComponent component) {
+		component.inject(this);
 	}
 
 	@Override
-	public void injectFragment(ActivityComponent component) {
-		component.inject(this);
+	public void onCreate(@Nullable Bundle savedInstanceState) {
+		super.onCreate(savedInstanceState);
+		requireNonNull(getActivity()).setTitle(R.string.groups_invite_members);
 	}
 
 	@Override

briar-android/src/main/java/org/briarproject/briar/android/privategroup/list/GroupListFragment.java

@@ -37,6 +37,7 @@ import javax.annotation.Nullable;
 import javax.inject.Inject;
 
 import static android.support.design.widget.Snackbar.LENGTH_INDEFINITE;
+import static java.util.Objects.requireNonNull;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
@@ -57,17 +58,23 @@ public class GroupListFragment extends BaseFragment implements
 	private GroupListAdapter adapter;
 	private Snackbar snackbar;
 
+	@Override
+	public void injectFragment(ActivityComponent component) {
+		component.inject(this);
+		controller.setGroupListListener(this);
+	}
+
 	@Nullable
 	@Override
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
 
-		getActivity().setTitle(R.string.groups_button);
+		requireNonNull(getActivity()).setTitle(R.string.groups_button);
 
 		View v = inflater.inflate(R.layout.list, container, false);
 
-		adapter = new GroupListAdapter(getContext(), this);
+		adapter = new GroupListAdapter(getActivity(), this);
 		list = v.findViewById(R.id.list);
 		list.setEmptyImage(R.drawable.ic_empty_state_group_list);
 		list.setEmptyText(R.string.groups_list_empty);
@@ -79,17 +86,11 @@ public class GroupListFragment extends BaseFragment implements
 		snackbar.getView().setBackgroundResource(R.color.briar_primary);
 		snackbar.setAction(R.string.show, this);
 		snackbar.setActionTextColor(ContextCompat
-				.getColor(getContext(), R.color.briar_button_text_positive));
+				.getColor(getActivity(), R.color.briar_button_text_positive));
 
 		return v;
 	}
 
-	@Override
-	public void injectFragment(ActivityComponent component) {
-		component.inject(this);
-		controller.setGroupListListener(this);
-	}
-
 	@Override
 	public void onStart() {
 		super.onStart();

briar-android/src/main/java/org/briarproject/briar/android/settings/SettingsFragment.java

@@ -75,6 +75,7 @@ import static org.briarproject.bramble.api.plugin.BluetoothConstants.PREF_BT_ENA
 import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_MOBILE;
 import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_NETWORK;
 import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_NETWORK_AUTOMATIC;
+import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_ONLY_WHEN_CHARGING;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.LogUtils.now;
@@ -111,6 +112,8 @@ public class SettingsFragment extends PreferenceFragmentCompat
 	public static final String NOTIFY_SIGN_IN = "pref_key_notify_sign_in";
 	public static final String TOR_NETWORK = "pref_key_tor_network";
 	public static final String TOR_MOBILE = "pref_key_tor_mobile_data";
+	public static final String TOR_ONLY_WHEN_CHARGING =
+			"pref_key_tor_only_when_charging";
 
 	private static final Logger LOG =
 			Logger.getLogger(SettingsFragment.class.getName());
@@ -120,6 +123,7 @@ public class SettingsFragment extends PreferenceFragmentCompat
 	private ListPreference enableBluetooth;
 	private ListPreference torNetwork;
 	private SwitchPreference torMobile;
+	private SwitchPreference torOnlyWhenCharging;
 	private SwitchPreference screenLock;
 	private ListPreference screenLockTimeout;
 	private SwitchPreference notifyPrivateMessages;
@@ -165,6 +169,8 @@ public class SettingsFragment extends PreferenceFragmentCompat
 		enableBluetooth = (ListPreference) findPreference("pref_key_bluetooth");
 		torNetwork = (ListPreference) findPreference(TOR_NETWORK);
 		torMobile = (SwitchPreference) findPreference(TOR_MOBILE);
+		torOnlyWhenCharging =
+				(SwitchPreference) findPreference(TOR_ONLY_WHEN_CHARGING);
 		screenLock = (SwitchPreference) findPreference(PREF_SCREEN_LOCK);
 		screenLockTimeout =
 				(ListPreference) findPreference(PREF_SCREEN_LOCK_TIMEOUT);
@@ -202,6 +208,7 @@ public class SettingsFragment extends PreferenceFragmentCompat
 		enableBluetooth.setOnPreferenceChangeListener(this);
 		torNetwork.setOnPreferenceChangeListener(this);
 		torMobile.setOnPreferenceChangeListener(this);
+		torOnlyWhenCharging.setOnPreferenceChangeListener(this);
 		screenLock.setOnPreferenceChangeListener(this);
 		screenLockTimeout.setOnPreferenceChangeListener(this);
 
@@ -362,6 +369,10 @@ public class SettingsFragment extends PreferenceFragmentCompat
 					torSettings.getBoolean(PREF_TOR_MOBILE, true);
 			torMobile.setChecked(torMobileSetting);
 
+			boolean torChargingSetting =
+					torSettings.getBoolean(PREF_TOR_ONLY_WHEN_CHARGING, false);
+			torOnlyWhenCharging.setChecked(torChargingSetting);
+
 			displayScreenLockSetting();
 
 			if (SDK_INT < 26) {
@@ -423,6 +434,7 @@ public class SettingsFragment extends PreferenceFragmentCompat
 		enableBluetooth.setEnabled(enabled);
 		torNetwork.setEnabled(enabled);
 		torMobile.setEnabled(enabled);
+		torOnlyWhenCharging.setEnabled(enabled);
 		if (!enabled) screenLock.setEnabled(false);
 		notifyPrivateMessages.setEnabled(enabled);
 		notifyGroupMessages.setEnabled(enabled);
@@ -519,6 +531,9 @@ public class SettingsFragment extends PreferenceFragmentCompat
 		} else if (preference == torMobile) {
 			boolean torMobileSetting = (Boolean) newValue;
 			storeTorMobileSetting(torMobileSetting);
+		} else if (preference == torOnlyWhenCharging) {
+			boolean torChargingSetting = (Boolean) newValue;
+			storeTorChargingSetting(torChargingSetting);
 		} else if (preference == screenLock) {
 			Settings s = new Settings();
 			s.putBoolean(PREF_SCREEN_LOCK, (Boolean) newValue);
@@ -585,6 +600,12 @@ public class SettingsFragment extends PreferenceFragmentCompat
 		mergeSettings(s, TOR_NAMESPACE);
 	}
 
+	private void storeTorChargingSetting(boolean torChargingSetting) {
+		Settings s = new Settings();
+		s.putBoolean(PREF_TOR_ONLY_WHEN_CHARGING, torChargingSetting);
+		mergeSettings(s, TOR_NAMESPACE);
+	}
+
 	private void storeBluetoothSettings(boolean btSetting) {
 		Settings s = new Settings();
 		s.putBoolean(PREF_BT_ENABLE, btSetting);

briar-android/src/main/java/org/briarproject/briar/android/sharing/BaseMessageFragment.java

@@ -37,7 +37,7 @@ public abstract class BaseMessageFragment extends BaseFragment
 	}
 
 	@Override
-	public View onCreateView(@Nullable LayoutInflater inflater,
+	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
 

briar-android/src/main/java/org/briarproject/briar/android/sharing/ShareBlogMessageFragment.java

@@ -1,14 +1,18 @@
 package org.briarproject.briar.android.sharing;
 
 import android.os.Bundle;
+import android.support.annotation.Nullable;
 import android.support.annotation.StringRes;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.activity.ActivityComponent;
 
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
 public class ShareBlogMessageFragment extends BaseMessageFragment {
 
 	public final static String TAG = ShareBlogMessageFragment.class.getName();
@@ -18,9 +22,9 @@ public class ShareBlogMessageFragment extends BaseMessageFragment {
 	}
 
 	@Override
-	public View onCreateView(LayoutInflater inflater, ViewGroup container,
-			Bundle savedInstanceState) {
-
+	public View onCreateView(LayoutInflater inflater,
+			@Nullable ViewGroup container,
+			@Nullable Bundle savedInstanceState) {
 		setTitle(R.string.blogs_sharing_share);
 		return super.onCreateView(inflater, container, savedInstanceState);
 	}
@@ -37,11 +41,6 @@ public class ShareBlogMessageFragment extends BaseMessageFragment {
 		return R.string.forum_share_message;
 	}
 
-	@Override
-	public void injectFragment(ActivityComponent component) {
-		component.inject(this);
-	}
-
 	@Override
 	public String getUniqueTag() {
 		return TAG;

briar-android/src/main/java/org/briarproject/briar/android/sharing/ShareForumMessageFragment.java

@@ -1,14 +1,18 @@
 package org.briarproject.briar.android.sharing;
 
 import android.os.Bundle;
+import android.support.annotation.Nullable;
 import android.support.annotation.StringRes;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.activity.ActivityComponent;
 
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
 public class ShareForumMessageFragment extends BaseMessageFragment {
 
 	public final static String TAG = ShareForumMessageFragment.class.getName();
@@ -18,8 +22,9 @@ public class ShareForumMessageFragment extends BaseMessageFragment {
 	}
 
 	@Override
-	public View onCreateView(LayoutInflater inflater, ViewGroup container,
-			Bundle savedInstanceState) {
+	public View onCreateView(LayoutInflater inflater,
+			@Nullable ViewGroup container,
+			@Nullable Bundle savedInstanceState) {
 
 		setTitle(R.string.forum_share_button);
 		return super.onCreateView(inflater, container, savedInstanceState);
@@ -37,11 +42,6 @@ public class ShareForumMessageFragment extends BaseMessageFragment {
 		return R.string.forum_share_message;
 	}
 
-	@Override
-	public void injectFragment(ActivityComponent component) {
-		component.inject(this);
-	}
-
 	@Override
 	public String getUniqueTag() {
 		return TAG;

briar-android/src/main/java/org/briarproject/briar/android/util/UiUtils.java

@@ -258,7 +258,8 @@ public class UiUtils {
 	}
 
 	public static boolean isSamsung7() {
-		return SDK_INT == 24 && MANUFACTURER.equalsIgnoreCase("Samsung");
+		return (SDK_INT == 24 || SDK_INT == 25) &&
+				MANUFACTURER.equalsIgnoreCase("Samsung");
 	}
 
 	public static void setFilterTouchesWhenObscured(View v, boolean filter) {

briar-android/src/main/java/org/briarproject/briar/android/view/ImagePreview.java

@@ -1,43 +1,27 @@
 package org.briarproject.briar.android.view;
 
 import android.content.Context;
-import android.graphics.Bitmap;
 import android.net.Uri;
 import android.support.annotation.Nullable;
 import android.support.constraint.ConstraintLayout;
-import android.support.v7.graphics.Palette;
+import android.support.v7.widget.RecyclerView;
 import android.util.AttributeSet;
 import android.view.LayoutInflater;
-import android.widget.ImageView;
-import android.widget.Toast;
-
-import com.bumptech.glide.load.DataSource;
-import com.bumptech.glide.load.engine.GlideException;
-import com.bumptech.glide.request.RequestListener;
-import com.bumptech.glide.request.target.Target;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.conversation.glide.GlideApp;
 
-import java.util.List;
+import java.util.Collection;
 
 import static android.content.Context.LAYOUT_INFLATER_SERVICE;
-import static android.graphics.Color.BLACK;
-import static android.graphics.Color.WHITE;
-import static android.support.v7.app.AppCompatDelegate.MODE_NIGHT_YES;
-import static android.support.v7.app.AppCompatDelegate.getDefaultNightMode;
-import static android.widget.Toast.LENGTH_LONG;
-import static com.bumptech.glide.load.engine.DiskCacheStrategy.NONE;
-import static com.bumptech.glide.load.resource.bitmap.DownsampleStrategy.FIT_CENTER;
+import static android.support.v4.content.ContextCompat.getColor;
+import static android.view.ViewGroup.LayoutParams.MATCH_PARENT;
 import static java.util.Objects.requireNonNull;
 
 @NotNullByDefault
 public class ImagePreview extends ConstraintLayout {
 
-	private final ImageView imageView;
-	private final int backgroundColor =
-			getDefaultNightMode() == MODE_NIGHT_YES ? BLACK : WHITE;
+	private final RecyclerView imageList;
 
 	@Nullable
 	private ImagePreviewListener listener;
@@ -59,9 +43,12 @@ public class ImagePreview extends ConstraintLayout {
 				context.getSystemService(LAYOUT_INFLATER_SERVICE));
 		inflater.inflate(R.layout.image_preview, this, true);
 
-		// find image view and set background color
-		imageView = findViewById(R.id.imageView);
-		imageView.setBackgroundColor(backgroundColor);
+		// set background color
+		setBackgroundColor(getColor(context, R.color.card_background));
+
+		// find list
+		imageList = findViewById(R.id.imageList);
+		imageList.addItemDecoration(new ImagePreviewDecoration(context));
 
 		// set cancel listener
 		findViewById(R.id.imageCancelButton).setOnClickListener(view -> {
@@ -73,46 +60,27 @@ public class ImagePreview extends ConstraintLayout {
 		this.listener = listener;
 	}
 
-	void showPreview(List<Uri> imageUris) {
+	void showPreview(Collection<Uri> imageUris) {
+		if (listener == null) throw new IllegalStateException();
+		if (imageUris.size() == 1) {
+			LayoutParams params = (LayoutParams) imageList.getLayoutParams();
+			params.width = MATCH_PARENT;
+			imageList.setLayoutParams(params);
+		}
 		setVisibility(VISIBLE);
-		GlideApp.with(imageView)
-				.asBitmap()
-				.load(imageUris.get(0))  // TODO show more than the first
-				.diskCacheStrategy(NONE)
-				.downsample(FIT_CENTER)
-				.addListener(new RequestListener<Bitmap>() {
-					@Override
-					public boolean onLoadFailed(@Nullable GlideException e,
-							Object model, Target<Bitmap> target,
-							boolean isFirstResource) {
-						if (listener != null) listener.onCancel();
-						Toast.makeText(imageView.getContext(),
-								R.string.image_attach_error, LENGTH_LONG)
-								.show();
-						return false;
-					}
-
-					@Override
-					public boolean onResourceReady(Bitmap resource,
-							Object model, Target<Bitmap> target,
-							DataSource dataSource, boolean isFirstResource) {
-						Palette.from(resource).generate(
-								ImagePreview.this::onPaletteGenerated);
-						return false;
-					}
-				})
-				.into(imageView);
+		imageList.setAdapter(new ImagePreviewAdapter(imageUris, listener));
 	}
 
-	void onPaletteGenerated(@Nullable Palette palette) {
-		if (palette == null) return;
-		int color = getDefaultNightMode() == MODE_NIGHT_YES ?
-				palette.getDarkMutedColor(backgroundColor) :
-				palette.getLightMutedColor(backgroundColor);
-		imageView.setBackgroundColor(color);
+	void removeUri(Uri uri) {
+		ImagePreviewAdapter adapter =
+				(ImagePreviewAdapter) imageList.getAdapter();
+		requireNonNull(adapter).removeUri(uri);
 	}
 
 	interface ImagePreviewListener {
+
+		void onUriError(Uri uri);
+
 		void onCancel();
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/view/ImagePreviewAdapter.java

@@ -0,0 +1,61 @@
+package org.briarproject.briar.android.view;
+
+import android.net.Uri;
+import android.support.annotation.LayoutRes;
+import android.support.v7.widget.RecyclerView.Adapter;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.briar.R;
+import org.briarproject.briar.android.view.ImagePreview.ImagePreviewListener;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+
+import static java.util.Objects.requireNonNull;
+
+@NotNullByDefault
+class ImagePreviewAdapter extends Adapter<ImagePreviewViewHolder> {
+
+	private final List<Uri> items;
+	private final ImagePreviewListener listener;
+	@LayoutRes
+	private final int layout;
+
+	ImagePreviewAdapter(Collection<Uri> items, ImagePreviewListener listener) {
+		this.items = new ArrayList<>(items);
+		this.listener = listener;
+		this.layout = items.size() == 1 ?
+				R.layout.list_item_image_preview_single :
+				R.layout.list_item_image_preview;
+	}
+
+	@Override
+	public ImagePreviewViewHolder onCreateViewHolder(ViewGroup viewGroup,
+			int type) {
+		View v = LayoutInflater.from(viewGroup.getContext())
+				.inflate(layout, viewGroup, false);
+		return new ImagePreviewViewHolder(v, requireNonNull(listener));
+	}
+
+	@Override
+	public void onBindViewHolder(ImagePreviewViewHolder viewHolder,
+			int position) {
+		viewHolder.bind(items.get(position));
+	}
+
+	@Override
+	public int getItemCount() {
+		return items.size();
+	}
+
+	void removeUri(Uri uri) {
+		int pos = items.indexOf(uri);
+		items.remove(uri);
+		notifyItemRemoved(pos);
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/view/ImagePreviewDecoration.java

@@ -0,0 +1,34 @@
+package org.briarproject.briar.android.view;
+
+import android.content.Context;
+import android.content.res.Resources;
+import android.graphics.Rect;
+import android.support.v7.widget.RecyclerView;
+import android.support.v7.widget.RecyclerView.ItemDecoration;
+import android.support.v7.widget.RecyclerView.State;
+import android.view.View;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.briar.R;
+
+@NotNullByDefault
+class ImagePreviewDecoration extends ItemDecoration {
+
+	private final int border;
+
+	ImagePreviewDecoration(Context ctx) {
+		Resources res = ctx.getResources();
+		border = res.getDimensionPixelSize(R.dimen.message_bubble_border);
+	}
+
+	@Override
+	public void getItemOffsets(Rect outRect, View view, RecyclerView parent,
+			State state) {
+		if (state.getItemCount() == parent.getChildAdapterPosition(view) + 1) {
+			// no decoration for last item in the list
+			return;
+		}
+		outRect.right = border;
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/view/ImagePreviewViewHolder.java

@@ -0,0 +1,73 @@
+package org.briarproject.briar.android.view;
+
+import android.graphics.drawable.Drawable;
+import android.net.Uri;
+import android.support.annotation.DrawableRes;
+import android.support.annotation.Nullable;
+import android.support.v7.widget.RecyclerView.ViewHolder;
+import android.view.View;
+import android.widget.ImageView;
+import android.widget.ProgressBar;
+
+import com.bumptech.glide.load.DataSource;
+import com.bumptech.glide.load.engine.GlideException;
+import com.bumptech.glide.request.RequestListener;
+import com.bumptech.glide.request.target.Target;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.briar.R;
+import org.briarproject.briar.android.conversation.glide.GlideApp;
+import org.briarproject.briar.android.view.ImagePreview.ImagePreviewListener;
+
+import static android.view.View.INVISIBLE;
+import static com.bumptech.glide.load.engine.DiskCacheStrategy.NONE;
+import static com.bumptech.glide.load.resource.bitmap.DownsampleStrategy.FIT_CENTER;
+import static com.bumptech.glide.load.resource.drawable.DrawableTransitionOptions.withCrossFade;
+
+@NotNullByDefault
+class ImagePreviewViewHolder extends ViewHolder {
+
+	@DrawableRes
+	private static final int ERROR_RES = R.drawable.ic_image_broken;
+
+	private final ImagePreviewListener listener;
+
+	private final ImageView imageView;
+	private final ProgressBar progressBar;
+
+	ImagePreviewViewHolder(View v, ImagePreviewListener listener) {
+		super(v);
+		this.listener = listener;
+		this.imageView = v.findViewById(R.id.imageView);
+		this.progressBar = v.findViewById(R.id.progressBar);
+	}
+
+	void bind(Uri uri) {
+		GlideApp.with(imageView)
+				.load(uri)
+				.diskCacheStrategy(NONE)
+				.error(ERROR_RES)
+				.downsample(FIT_CENTER)
+				.transition(withCrossFade())
+				.addListener(new RequestListener<Drawable>() {
+					@Override
+					public boolean onLoadFailed(@Nullable GlideException e,
+							Object model, Target<Drawable> target,
+							boolean isFirstResource) {
+						listener.onUriError(uri);
+						progressBar.setVisibility(INVISIBLE);
+						return false;
+					}
+
+					@Override
+					public boolean onResourceReady(Drawable resource,
+							Object model, Target<Drawable> target,
+							DataSource dataSource, boolean isFirstResource) {
+						progressBar.setVisibility(INVISIBLE);
+						return false;
+					}
+				})
+				.into(imageView);
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/view/TextAttachmentController.java

@@ -1,36 +1,48 @@
 package org.briarproject.briar.android.view;
 
+import android.app.Activity;
 import android.content.ClipData;
+import android.content.Context;
 import android.content.Intent;
 import android.net.Uri;
 import android.os.Parcel;
 import android.os.Parcelable;
-import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import android.support.annotation.UiThread;
 import android.support.v4.view.AbsSavedState;
+import android.support.v7.app.AlertDialog.Builder;
 import android.support.v7.widget.AppCompatImageButton;
+import android.widget.Toast;
 
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.view.ImagePreview.ImagePreviewListener;
 
 import java.util.ArrayList;
 import java.util.List;
 
+import uk.co.samuelwall.materialtaptargetprompt.MaterialTapTargetPrompt;
+import uk.co.samuelwall.materialtaptargetprompt.MaterialTapTargetPrompt.PromptStateChangeListener;
+
 import static android.content.Intent.ACTION_GET_CONTENT;
 import static android.content.Intent.ACTION_OPEN_DOCUMENT;
 import static android.content.Intent.CATEGORY_OPENABLE;
 import static android.content.Intent.EXTRA_ALLOW_MULTIPLE;
 import static android.os.Build.VERSION.SDK_INT;
+import static android.support.v4.content.ContextCompat.getColor;
 import static android.support.v4.view.AbsSavedState.EMPTY_STATE;
 import static android.view.View.GONE;
 import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
+import static android.widget.Toast.LENGTH_LONG;
 import static java.util.Collections.emptyList;
-import static java.util.Collections.singletonList;
 import static java.util.Objects.requireNonNull;
+import static org.briarproject.briar.android.util.UiUtils.resolveColorAttribute;
+import static uk.co.samuelwall.materialtaptargetprompt.MaterialTapTargetPrompt.STATE_DISMISSED;
+import static uk.co.samuelwall.materialtaptargetprompt.MaterialTapTargetPrompt.STATE_FINISHED;
 
 @UiThread
+@NotNullByDefault
 public class TextAttachmentController extends TextSendController
 		implements ImagePreviewListener {
 
@@ -40,6 +52,7 @@ public class TextAttachmentController extends TextSendController
 	private final AttachImageListener imageListener;
 
 	private CharSequence textHint;
+	private boolean hasImageSupport = false;
 	private List<Uri> imageUris = emptyList();
 
 	public TextAttachmentController(TextInputView v, ImagePreview imagePreview,
@@ -76,20 +89,41 @@ public class TextAttachmentController extends TextSendController
 		return !imageUris.isEmpty();
 	}
 
+	/***
+	 * By default, image support is disabled.
+	 * Once you know that it is supported in the current context,
+	 * call this method to enable it.
+	 */
+	public void setImagesSupported() {
+		hasImageSupport = true;
+		imageButton.setImageResource(R.drawable.ic_image);
+	}
+
 	private void onImageButtonClicked() {
+		if (!hasImageSupport) {
+			Context ctx = imageButton.getContext();
+			Builder builder = new Builder(ctx, R.style.OnboardingDialogTheme);
+			builder.setTitle(
+					ctx.getString(R.string.dialog_title_no_image_support));
+			builder.setMessage(
+					ctx.getString(R.string.dialog_message_no_image_support));
+			builder.setPositiveButton(R.string.got_it, null);
+			builder.show();
+			return;
+		}
 		Intent intent = new Intent(SDK_INT >= 19 ?
 				ACTION_OPEN_DOCUMENT : ACTION_GET_CONTENT);
 		intent.addCategory(CATEGORY_OPENABLE);
 		intent.setType("image/*");
-		if (SDK_INT >= 18)  // TODO set true to allow attaching multiple images
-			intent.putExtra(EXTRA_ALLOW_MULTIPLE, false);
+		if (SDK_INT >= 18) intent.putExtra(EXTRA_ALLOW_MULTIPLE, true);
 		requireNonNull(imageListener).onAttachImage(intent);
 	}
 
 	public void onImageReceived(@Nullable Intent resultData) {
 		if (resultData == null) return;
 		if (resultData.getData() != null) {
-			imageUris = singletonList(resultData.getData());
+			imageUris = new ArrayList<>(1);
+			imageUris.add(resultData.getData());
 			onNewUris();
 		} else if (SDK_INT >= 18 && resultData.getClipData() != null) {
 			ClipData clipData = resultData.getClipData();
@@ -163,20 +197,50 @@ public class TextAttachmentController extends TextSendController
 
 	@Override
 	@Nullable
-	public Parcelable onRestoreInstanceState(@NonNull Parcelable inState) {
+	public Parcelable onRestoreInstanceState(Parcelable inState) {
 		SavedState state = (SavedState) inState;
-		imageUris = state.imageUris;
+		imageUris = requireNonNull(state.imageUris);
 		onNewUris();
 		return state.getSuperState();
 	}
 
+	@Override
+	public void onUriError(Uri uri) {
+		imageUris.remove(uri);
+		imagePreview.removeUri(uri);
+		if (imageUris.isEmpty()) onCancel();
+		Toast.makeText(textInput.getContext(), R.string.image_attach_error,
+				LENGTH_LONG).show();
+	}
+
 	@Override
 	public void onCancel() {
 		textInput.clearText();
 		reset();
 	}
 
+	public void showImageOnboarding(Activity activity,
+			Runnable onOnboardingSeen) {
+		PromptStateChangeListener listener = (prompt, state) -> {
+			if (state == STATE_DISMISSED || state == STATE_FINISHED) {
+				onOnboardingSeen.run();
+			}
+		};
+		int color = resolveColorAttribute(activity, R.attr.colorControlNormal);
+		new MaterialTapTargetPrompt.Builder(activity,
+				R.style.OnboardingDialogTheme).setTarget(imageButton)
+				.setPrimaryText(R.string.dialog_title_image_support)
+				.setSecondaryText(R.string.dialog_message_image_support)
+				.setBackgroundColour(getColor(activity, R.color.briar_primary))
+				.setIcon(R.drawable.ic_image)
+				.setIconDrawableColourFilter(color)
+				.setPromptStateChangeListener(listener)
+				.show();
+	}
+
 	private static class SavedState extends AbsSavedState {
+
+		@Nullable
 		private List<Uri> imageUris;
 
 		private SavedState(Parcelable superState) {
@@ -195,16 +259,18 @@ public class TextAttachmentController extends TextSendController
 			out.writeList(imageUris);
 		}
 
-		public static final Parcelable.Creator<SavedState> CREATOR
-				= new Parcelable.Creator<SavedState>() {
-			public SavedState createFromParcel(Parcel in) {
-				return new SavedState(in);
-			}
+		public static final Creator<SavedState> CREATOR =
+				new Creator<SavedState>() {
+					@Override
+					public SavedState createFromParcel(Parcel in) {
+						return new SavedState(in);
+					}
 
-			public SavedState[] newArray(int size) {
-				return new SavedState[size];
-			}
-		};
+					@Override
+					public SavedState[] newArray(int size) {
+						return new SavedState[size];
+					}
+				};
 	}
 
 	public interface AttachImageListener {

briar-android/src/main/res/drawable/ic_image_off.xml

@@ -0,0 +1,11 @@
+<vector
+	xmlns:android="http://schemas.android.com/apk/res/android"
+	android:width="24dp"
+	android:height="24dp"
+	android:alpha="0.56"
+	android:viewportHeight="24"
+	android:viewportWidth="24">
+	<path
+		android:fillColor="#000"
+		android:pathData="M2.28,3L1,4.27L3,6.27V19A2,2 0 0,0 5,21H17.73L19.73,23L21,21.72L2.28,3M4.83,3L21,19.17V5C21,3.89 20.1,3 19,3H4.83M8.5,13.5L11,16.5L12,15.25L14.73,18H5L8.5,13.5Z"/>
+</vector>

briar-android/src/main/res/layout/activity_conversation.xml

@@ -34,7 +34,7 @@
 					android:layout_marginLeft="@dimen/margin_medium"
 					android:layout_marginStart="@dimen/margin_medium"
 					android:ellipsize="end"
-					android:gravity="center"
+					android:gravity="center_vertical"
 					android:maxLines="1"
 					android:textColor="@color/action_bar_text"
 					tools:text="Contact Name of someone who chose a long name"/>
@@ -49,7 +49,8 @@
 		android:id="@+id/conversationView"
 		android:layout_width="match_parent"
 		android:layout_height="0dp"
-		android:layout_weight="2"/>
+		android:layout_weight="2"
+		app:scrollToEnd="false"/>
 
 	<org.briarproject.briar.android.view.ImagePreview
 		android:id="@+id/imagePreview"

briar-android/src/main/res/layout/activity_image.xml

@@ -8,12 +8,11 @@
 	android:background="@color/briar_black"
 	tools:context=".android.conversation.ImageActivity">
 
-	<com.github.chrisbanes.photoview.PhotoView
-		android:id="@+id/photoView"
+	<android.support.v4.view.ViewPager
+		android:id="@+id/viewPager"
 		android:layout_width="match_parent"
 		android:layout_height="match_parent"
-		tools:ignore="ContentDescription"
-		tools:srcCompat="@tools:sample/backgrounds/scenic"/>
+		tools:background="@color/briar_green_light"/>
 
 	<android.support.design.widget.AppBarLayout
 		android:id="@+id/appBarLayout"

briar-android/src/main/res/layout/activity_threaded_conversation.xml

@@ -13,7 +13,8 @@
 	<FrameLayout
 		android:layout_width="match_parent"
 		android:layout_height="0dp"
-		android:layout_weight="1">
+		android:layout_weight="1"
+		android:background="@color/thread_item_background">
 
 		<org.briarproject.briar.android.view.BriarRecyclerView
 			android:id="@+id/list"

briar-android/src/main/res/layout/fragment_image.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<com.github.chrisbanes.photoview.PhotoView
+	android:id="@+id/photoView"
+	xmlns:android="http://schemas.android.com/apk/res/android"
+	xmlns:tools="http://schemas.android.com/tools"
+	android:layout_width="match_parent"
+	android:layout_height="match_parent"
+	tools:ignore="ContentDescription"
+	tools:srcCompat="@tools:sample/backgrounds/scenic"/>

briar-android/src/main/res/layout/image_preview.xml

@@ -13,21 +13,23 @@
 		android:id="@+id/divider"
 		style="@style/Divider.Horizontal"
 		android:layout_alignParentTop="true"
-		app:layout_constraintBottom_toTopOf="@+id/imageView"
+		app:layout_constraintBottom_toTopOf="@+id/imageList"
 		app:layout_constraintEnd_toEndOf="parent"
 		app:layout_constraintStart_toStartOf="parent"
 		app:layout_constraintTop_toTopOf="parent"/>
 
-	<ImageView
-		android:id="@+id/imageView"
-		android:layout_width="match_parent"
+	<android.support.v7.widget.RecyclerView
+		android:id="@+id/imageList"
+		android:layout_width="wrap_content"
 		android:layout_height="match_parent"
+		android:orientation="horizontal"
+		app:layoutManager="android.support.v7.widget.LinearLayoutManager"
 		app:layout_constraintBottom_toBottomOf="parent"
 		app:layout_constraintEnd_toEndOf="parent"
 		app:layout_constraintStart_toStartOf="parent"
 		app:layout_constraintTop_toBottomOf="@+id/divider"
 		tools:ignore="ContentDescription"
-		tools:srcCompat="@tools:sample/avatars"/>
+		tools:listitem="@layout/list_item_image"/>
 
 	<android.support.design.widget.FloatingActionButton
 		android:id="@+id/imageCancelButton"

briar-android/src/main/res/layout/list_item_image_preview.xml

@@ -0,0 +1,35 @@
+<?xml version="1.0" encoding="utf-8"?>
+<android.support.constraint.ConstraintLayout
+	xmlns:android="http://schemas.android.com/apk/res/android"
+	xmlns:app="http://schemas.android.com/apk/res-auto"
+	xmlns:tools="http://schemas.android.com/tools"
+	android:layout_width="wrap_content"
+	android:layout_height="match_parent"
+	tools:layout_height="200dp">
+
+	<ProgressBar
+		android:id="@+id/progressBar"
+		style="?android:attr/progressBarStyleLarge"
+		android:layout_width="wrap_content"
+		android:layout_height="wrap_content"
+		android:layout_margin="16dp"
+		app:layout_constraintBottom_toBottomOf="parent"
+		app:layout_constraintEnd_toEndOf="parent"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toTopOf="parent"/>
+
+	<ImageView
+		android:id="@+id/imageView"
+		android:layout_width="0dp"
+		android:layout_height="match_parent"
+		android:scaleType="centerCrop"
+		app:layout_constraintBottom_toBottomOf="parent"
+		app:layout_constraintDimensionRatio="1:1"
+		app:layout_constraintEnd_toEndOf="parent"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toTopOf="parent"
+		tools:ignore="ContentDescription"
+		tools:srcCompat="@tools:sample/avatars"
+		tools:visibility="visible"/>
+
+</android.support.constraint.ConstraintLayout>

briar-android/src/main/res/layout/list_item_image_preview_single.xml

@@ -0,0 +1,33 @@
+<?xml version="1.0" encoding="utf-8"?>
+<android.support.constraint.ConstraintLayout
+	xmlns:android="http://schemas.android.com/apk/res/android"
+	xmlns:app="http://schemas.android.com/apk/res-auto"
+	xmlns:tools="http://schemas.android.com/tools"
+	android:layout_width="match_parent"
+	android:layout_height="match_parent"
+	tools:layout_height="200dp">
+
+	<ProgressBar
+		android:id="@+id/progressBar"
+		style="?android:attr/progressBarStyleLarge"
+		android:layout_width="wrap_content"
+		android:layout_height="wrap_content"
+		android:layout_margin="16dp"
+		app:layout_constraintBottom_toBottomOf="parent"
+		app:layout_constraintEnd_toEndOf="parent"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toTopOf="parent"/>
+
+	<ImageView
+		android:id="@+id/imageView"
+		android:layout_width="0dp"
+		android:layout_height="0dp"
+		app:layout_constraintBottom_toBottomOf="parent"
+		app:layout_constraintEnd_toEndOf="parent"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toTopOf="parent"
+		tools:ignore="ContentDescription"
+		tools:srcCompat="@tools:sample/backgrounds/scenic"
+		tools:visibility="visible"/>
+
+</android.support.constraint.ConstraintLayout>

briar-android/src/main/res/layout/text_input_view.xml

@@ -40,7 +40,7 @@
 				android:focusable="true"
 				android:padding="4dp"
 				android:scaleType="center"
-				android:src="@drawable/ic_image"
+				android:src="@drawable/ic_image_off"
 				android:visibility="invisible"
 				app:tint="?attr/colorControlNormal"/>
 

briar-android/src/main/res/values-ar/strings.xml

@@ -141,6 +141,8 @@
   <string name="dialog_title_delete_contact">تأكيد حذف جهة الإتصال</string>
   <string name="dialog_message_delete_contact">هل أنت متأكد/ة من أنك تريد حذف جهة الإتصال هذه وكل الرسائل المتبادلة بينكما؟</string>
   <string name="contact_deleted_toast">تم حذف جهة اتصال</string>
+  <!--This is shown in the action bar when opening an image in fullscreen that the user sent-->
+  <string name="you">أنتَ/أنتِ</string>
   <!--Adding Contacts-->
   <string name="add_contact_title">إضافة جهة اتصال</string>
   <string name="face_to_face">لا بد من مقابلة الشخص الذي تريد/ين إضافته كجهة اتصال.\n\nهذا سيمنع أي شخص من انتحال شخصيتك أو قراءة رسائلك في المستقبل.</string>

briar-android/src/main/res/values-ca/strings.xml

@@ -48,6 +48,7 @@
   <string name="download_briar_button">Descarrega Briar 1.0</string>
   <string name="startup_open_database">S\'està desxifrant la base de dades...</string>
   <string name="startup_migrate_database">S\'està actualitzant la base de dades...</string>
+  <string name="startup_compact_database">Compactant la base de dades...</string>
   <!--Navigation Drawer-->
   <string name="nav_drawer_open_description">Obre el calaix de navegació</string>
   <string name="nav_drawer_close_description">Tanca el calaix de navegació</string>
@@ -115,12 +116,14 @@
   <string name="date_no_private_messages">Sense missatges.</string>
   <string name="no_private_messages">No hi ha cap missatge</string>
   <string name="message_hint">Escriviu un missatge</string>
+  <string name="set_contact_alias">Canvia el nom del contacte</string>
   <string name="set_contact_alias_hint">Nom del contacte</string>
   <string name="set_alias_button">Canvia</string>
   <string name="delete_contact">Suprimeix aquest contacte</string>
   <string name="dialog_title_delete_contact">Confirmeu la supressió del contacte</string>
   <string name="dialog_message_delete_contact">Segur que voleu suprimir aquest contacte i tots els missatges que us heu intercanviat?</string>
   <string name="contact_deleted_toast">S\'ha suprimit el contacte</string>
+  <!--This is shown in the action bar when opening an image in fullscreen that the user sent-->
   <!--Adding Contacts-->
   <string name="add_contact_title">Afegiu un contacte</string>
   <string name="face_to_face">Heu de coincidir en el mateix lloc amb la persona que voleu afegir com a contacte.\n\nD\'aquesta manera evitareu que algú suplanti les vostres identitats o pugui llegir els vostres missatges en el futur.</string>
@@ -131,6 +134,8 @@
   <string name="contact_added_toast">S\'ha afegit el contacte %s</string>
   <string name="contact_already_exists">El contacte %s ja existia</string>
   <string name="qr_code_invalid">El codi QR és invàlid</string>
+  <string name="qr_code_too_old">El codi QR que heu escanejat prové d\'una versió antiga de %s.\n\nDemaneu al vostre contacte que actualitzi a l\'última versió i torneu a provar-ho.</string>
+  <string name="qr_code_too_new">El codi QR que heu escanejat prové d\'una versió nova de %s.\n\nActualitzeu a l\'última versió i torneu a provar-ho.</string>
   <string name="camera_error">Error de la càmera</string>
   <string name="connecting_to_device">Connectant-se al dispositiu\u2026</string>
   <string name="authenticating_with_device">Autenticant-se amb el dispositiu\u2026</string>
@@ -340,8 +345,10 @@
   <string name="tor_mobile_data_title">Usa dades mòbils</string>
   <!--Settings Security and Panic-->
   <string name="security_settings_title">Seguretat</string>
+  <string name="pref_lock_title">Bloqueig de l\'aplicació</string>
   <string name="pref_lock_summary">Usa el bloqueig de pantalla del dispositiu per protegir Briar mentre inicieu la sessió</string>
   <string name="pref_lock_disabled_summary">Per utilitzar aquesta funció, configureu el bloqueig de pantalla en el vostre dispositiu</string>
+  <string name="pref_lock_timeout_title">Temps d\'inactivitat per al bloqueig</string>
   <!--The %s placeholder is replaced with the following time spans, e.g. 5 Minutes, 1 Hour-->
   <string name="pref_lock_timeout_summary">Briar es bloquejarà automàticament després de %s de no usar-se.</string>
   <!--Will be shown in a list of lock times. Should fit into the %s of "automatically lock it after %s"-->
@@ -370,6 +377,7 @@
   <string name="panic_app_setting_none">Cap</string>
   <string name="dialog_title_connect_panic_app">Confirmeu l\'aplicació de pànic</string>
   <string name="dialog_message_connect_panic_app">Segur que voleu permetre que %1$s desencadeni accions destructives a conseqüència del botó de pànic?</string>
+  <string name="panic_setting_destructive_action">Accions destructives</string>
   <string name="panic_setting_signout_title">Tanca la sessió</string>
   <string name="panic_setting_signout_summary">Tanca la sessió de Briar si es prem un botó de pànic</string>
   <string name="purge_setting_title">Esborreu el compte</string>
@@ -431,6 +439,10 @@
   <!--Permission Requests-->
   <string name="permission_camera_title">Permís de la càmera</string>
   <string name="permission_camera_request_body">Per escanejar el codi QR, Briar necessita accedir a la càmera.</string>
+  <string name="permission_location_title">Permís d\'accés a l\'ubicació</string>
+  <string name="permission_location_request_body">Per trobar dispositius Bluetooth, Briar necessita la vostra ubicació.\n\nBriar no guarda la vostra ubicació ni la comparteix amb ningú.</string>
+  <string name="permission_camera_location_title">Permís d\'accés a la càmera i l\'ubicació</string>
+  <string name="permission_camera_location_request_body">Per escanejar el codi QR, Briar necessita accedir a la càmera.\n\nPer trobar dispositius Bluetooth, Briar necessita la vostra ubicació.\n\nBriar no guarda la vostra ubicació ni la comparteix amb ningú.</string>
   <string name="permission_camera_denied_body">Heu denegat l\'accés a la càmera però per afegir contactes cal utilitzar la càmera.\n\nRecomanem que permeteu l\'accés a la càmera.</string>
   <string name="qr_code">Codi QR</string>
   <string name="show_qr_code_fullscreen">Mostra el codi QR a pantalla completa</string>
@@ -443,9 +455,15 @@
   <string name="lock_tap_to_unlock">Toqueu per desbloquejar-lo</string>
   <!--Screenshots-->
   <!--This is a name to be used in screenshots. Feel free to change it to a local name.-->
+  <string name="screenshot_alice">Alice</string>
   <!--This is a name to be used in screenshots. Feel free to change it to a local name.-->
+  <string name="screenshot_bob">Bob</string>
   <!--This is a name to be used in screenshots. Feel free to change it to a local name.-->
+  <string name="screenshot_carol">Carol</string>
   <!--This is a message to be used in screenshots. Please use the same translation for Bob!-->
+  <string name="screenshot_message_1">Hola Bob!</string>
   <!--This is a message to be used in screenshots. Please use the same translation for Alice!-->
+  <string name="screenshot_message_2">Hola Alice! Gràcies per recomanar-me Briar!</string>
   <!--This is a message to be used in screenshots.-->
+  <string name="screenshot_message_3">De res, espero que t\'agradi 😀</string>
 </resources>

briar-android/src/main/res/values-cs/strings.xml

@@ -122,6 +122,8 @@
   <string name="dialog_title_delete_contact">Potvrdit odstranění kontaktu</string>
   <string name="dialog_message_delete_contact">Jste si jisti, že chcete odstranit kontakt a všechny související zprávy s tímto kontaktem?</string>
   <string name="contact_deleted_toast">Kontakt odstraněn</string>
+  <!--This is shown in the action bar when opening an image in fullscreen that the user sent-->
+  <string name="you">Vy</string>
   <!--Adding Contacts-->
   <string name="add_contact_title">Přidat kontakt</string>
   <string name="face_to_face">Musíte se osobně setkat s osobou, kterou si chcete přidat jako kontakt.\n\nToto v budoucnu zabrání komukoli, aby se za vás vydával nebo četl Vaše zprávy.</string>
@@ -334,6 +336,8 @@
   <string name="pref_lock_timeout_60">1 hodina</string>
   <string name="pref_lock_timeout_never">Nikdy</string>
   <string name="change_password">Změnit heslo</string>
+  <string name="current_password">Současné heslo</string>
+  <string name="choose_new_password">Nové heslo</string>
   <string name="password_changed">Heslo bylo změněno.</string>
   <string name="panic_setting">Nastavení tlačítka Paniky</string>
   <string name="panic_setting_title">Tlačítko Paniky</string>

briar-android/src/main/res/values-de/strings.xml

@@ -48,6 +48,7 @@
   <string name="download_briar_button">Lade Briar 1.0 herunter</string>
   <string name="startup_open_database">Datenbank wird entschlüsselt...</string>
   <string name="startup_migrate_database">Datenbank wird aktualisiert...</string>
+  <string name="startup_compact_database">Datenbank komprimieren...</string>
   <!--Navigation Drawer-->
   <string name="nav_drawer_open_description">Navigationsleiste öffnen</string>
   <string name="nav_drawer_close_description">Navigationsleiste schliessen</string>
@@ -115,12 +116,23 @@
   <string name="date_no_private_messages">Keine Nachrichten.</string>
   <string name="no_private_messages">Keine Nachrichten vorhanden</string>
   <string name="message_hint">Nachricht eingeben</string>
+  <string name="image_caption_hint">Überschrift hinzufügen (optional)</string>
+  <string name="image_attach">Bild anhängen</string>
+  <string name="image_attach_error">Konnte kein Bild anhängen</string>
+  <string name="set_contact_alias">Kontaktnamen ändern</string>
   <string name="set_contact_alias_hint">Name des Kontakts</string>
   <string name="set_alias_button">Ändern</string>
   <string name="delete_contact">Kontakt löschen</string>
   <string name="dialog_title_delete_contact">Löschen des Kontakts bestätigen</string>
   <string name="dialog_message_delete_contact">Bist du sicher, dass du diesen Kontakt und alle dazugehörigen Nachrichten löschen möchtest?</string>
   <string name="contact_deleted_toast">Kontakt gelöscht</string>
+  <!--This is shown in the action bar when opening an image in fullscreen that the user sent-->
+  <string name="you">Sie</string>
+  <string name="save_image">Bild speichern</string>
+  <string name="dialog_title_save_image">Bild speichern?</string>
+  <string name="dialog_message_save_image">Gespeicherte Bilder können von vielen anderen Apps eingesehen werden.\n\nBist Du sicher, dass Du das Bild speichern möchtest?</string>
+  <string name="save_image_success">Bild wurde gespeichert.</string>
+  <string name="save_image_error">Konnte Bild nicht speichern.</string>
   <!--Adding Contacts-->
   <string name="add_contact_title">Kontakt hinzufügen</string>
   <string name="face_to_face">Um einen neuen Kontakt hinzuzufügen, ist es notwendig, dass sich beide Kontakte an einem Ort treffen.\n\nDadurch wird betrügerische Identitätsvortäuschung und unautorisierter Kommunikationszugriff verhindert.</string>
@@ -131,6 +143,8 @@
   <string name="contact_added_toast">Kontakt hinzugefügt: %s</string>
   <string name="contact_already_exists">Kontakt %s existiert bereits</string>
   <string name="qr_code_invalid">Der QR-Code ist ungültig</string>
+  <string name="qr_code_too_old">Der QR-Code, den Du eingescannt hast, kommt von einer älteren Version von %s.\n\nBitte deinen Kontakt, zur neuesten Version upzudaten, und probiere es erneut.</string>
+  <string name="qr_code_too_new">Der QR-Code, den Du gescannt hast, kommt von einer neueren Version von .\n\nBitte update %s auf die neueste Version und versuche es erneut.</string>
   <string name="camera_error">Kamerafehler</string>
   <string name="connecting_to_device">Verbinde mit Gerät\u2026</string>
   <string name="authenticating_with_device">Authentifiziere Gerät\u2026</string>
@@ -341,7 +355,7 @@
   <!--Settings Security and Panic-->
   <string name="security_settings_title">Sicherheit</string>
   <string name="pref_lock_summary">Systemsperrbildschirm benutzen um Briar zu schützen, während angemeldet</string>
-  <string name="pref_lock_disabled_summary">Um dieses Feature zu benutzen aktiviere den Systemsperrbildschirm</string>
+  <string name="pref_lock_disabled_summary">Um dieses Feature zu benutzen, aktiviere den Systemsperrbildschirm</string>
   <!--The %s placeholder is replaced with the following time spans, e.g. 5 Minutes, 1 Hour-->
   <string name="pref_lock_timeout_summary">Briar automatisch nach %s sperren, wenn unbenutzt.</string>
   <!--Will be shown in a list of lock times. Should fit into the %s of "automatically lock it after %s"-->
@@ -370,6 +384,7 @@
   <string name="panic_app_setting_none">Keine</string>
   <string name="dialog_title_connect_panic_app">Bestätige die Panik-App</string>
   <string name="dialog_message_connect_panic_app">Bist du sicher, dass du %1$s erlauben willst, Panik-Button-Ereignisse auszulösen?</string>
+  <string name="panic_setting_destructive_action">Zerstörerische Aktionen</string>
   <string name="panic_setting_signout_title">Abmelden</string>
   <string name="panic_setting_signout_summary">Von Briar abmelden, wenn ein Panik-Button aktiviert wird</string>
   <string name="purge_setting_title">Konto löschen</string>
@@ -378,8 +393,8 @@
   <string name="uninstall_setting_summary">Diese Aktion benötigt eine manuelle Bestätigung im Falle eines Panik-Ereignisses</string>
   <!--Settings Notifications-->
   <string name="notification_settings_title">Benachrichtigungen</string>
-  <string name="notify_sign_in_title">Anmeldeerinerung</string>
-  <string name="notify_sign_in_summary">Zeige eine Erinnerung bei Systemstart oder die App geupdated wurde</string>
+  <string name="notify_sign_in_title">Anmeldeerinnerung</string>
+  <string name="notify_sign_in_summary">Zeigt eine Erinnerung an, wenn das Telefon startet oder die App aktualisiert wurde</string>
   <string name="notify_private_messages_setting_title">Private Nachrichten</string>
   <string name="notify_private_messages_setting_summary">Benachrichtigungen für private Nachrichten anzeigen</string>
   <string name="notify_private_messages_setting_summary_26">Benachrichtigungen für private Nachrichten konfigurieren</string>
@@ -431,21 +446,31 @@
   <!--Permission Requests-->
   <string name="permission_camera_title">Berechtigung Kamera</string>
   <string name="permission_camera_request_body">Um den QR-Code zu scannen, benötigt Briar Zugriff auf die Kamera.</string>
+  <string name="permission_location_title">Berechtigung Standort</string>
+  <string name="permission_location_request_body">Um Bluetooth-Geräte zu  finden, braucht Briar Zugriff auf Deinen Standort.\n\nBriar speichert weder Deinen Standort noch gibt es ihn an andere weiter.</string>
+  <string name="permission_camera_location_title">Kamera und Standort</string>
+  <string name="permission_camera_location_request_body">Um den QR-Code zu scannen, brauch Briar Zugriff auf die Kamera.\n\nUm Bluetooth-Geräte zu finden, braucht Briar Zugriff auf Deinen Standort.\n\nBriar speichert weder Deinen Standort noch gibt es ihn an andere weiter.</string>
   <string name="permission_camera_denied_body">Du hast den Zugriff auf die Kamera verweigert, aber das Hinzufügen von Kontakten erfordert die Verwendung der Kamera.\n\nBitte gewähre den Zugriff.</string>
   <string name="qr_code">QR-Code</string>
   <string name="show_qr_code_fullscreen">QR-Code im Vollbildmodus anzeigen</string>
   <!--App Locking-->
   <string name="lock_unlock">Briar entsperren</string>
-  <string name="lock_unlock_verbose">Um Briar zu entsperren, gib deinen Systempin,-geste oder -password ein</string>
+  <string name="lock_unlock_verbose">Um Briar zu entsperren, gib deine System-PIN, Muster oder Passwort ein</string>
   <string name="lock_unlock_fingerprint_description">Um fortzufahren berühre den Fingerabdrucksensor mit einem registrierten Finger</string>
-  <string name="lock_unlock_password">Benutze Passwort</string>
+  <string name="lock_unlock_password">Passwort benutzen</string>
   <string name="lock_is_locked">Briar ist gesperrt</string>
   <string name="lock_tap_to_unlock">Zum Entsperren antippen</string>
   <!--Screenshots-->
   <!--This is a name to be used in screenshots. Feel free to change it to a local name.-->
+  <string name="screenshot_alice">Alice</string>
   <!--This is a name to be used in screenshots. Feel free to change it to a local name.-->
+  <string name="screenshot_bob">Bob</string>
   <!--This is a name to be used in screenshots. Feel free to change it to a local name.-->
+  <string name="screenshot_carol">Carol</string>
   <!--This is a message to be used in screenshots. Please use the same translation for Bob!-->
+  <string name="screenshot_message_1">Hi Bob!</string>
   <!--This is a message to be used in screenshots. Please use the same translation for Alice!-->
+  <string name="screenshot_message_2">Hi Alice! Danke, dass du mir von Briar erzählt hast!</string>
   <!--This is a message to be used in screenshots.-->
+  <string name="screenshot_message_3">Kein Problem, ich hoffe, es gefällt dir 😀</string>
 </resources>

briar-android/src/main/res/values-es/strings.xml

@@ -116,6 +116,9 @@
   <string name="date_no_private_messages">Sin mensajes.</string>
   <string name="no_private_messages">No hay mensajes que mostrar</string>
   <string name="message_hint">Escribe un mensaje</string>
+  <string name="image_caption_hint">Añade una breve descripción (opcional)</string>
+  <string name="image_attach">Adjuntar imagen</string>
+  <string name="image_attach_error">No se pudo adjuntar imagen</string>
   <string name="set_contact_alias">Cambiar nombre del contacto</string>
   <string name="set_contact_alias_hint">Nombre del contacto</string>
   <string name="set_alias_button">Cambiar</string>
@@ -123,6 +126,13 @@
   <string name="dialog_title_delete_contact">Confirmar eliminación de contacto</string>
   <string name="dialog_message_delete_contact">¿Seguro que quieres eliminar este contacto y todos los mensajes intercambiados entre vosotros?</string>
   <string name="contact_deleted_toast">Contacto eliminado</string>
+  <!--This is shown in the action bar when opening an image in fullscreen that the user sent-->
+  <string name="you">Tú</string>
+  <string name="save_image">Guardar imagen</string>
+  <string name="dialog_title_save_image">¿Guardar imagen?</string>
+  <string name="dialog_message_save_image">Guardando esta imagen le permitirá a otras aplicaciones accederla.\n\n¿Estás seguro que quieres guardarla?</string>
+  <string name="save_image_success">La imagen fue guardada</string>
+  <string name="save_image_error">No se pudo guardar imagen</string>
   <!--Adding Contacts-->
   <string name="add_contact_title">Añadir un contacto</string>
   <string name="face_to_face">Debes reunirte con la persona a la que quieras añadir como contacto.\n\nHaciéndolo así prevendrás que nadie te suplante o pueda leer tus mensajes en el futuro.</string>

briar-android/src/main/res/values-eu/strings.xml

@@ -116,6 +116,9 @@
   <string name="date_no_private_messages">Ez dago mezurik.</string>
   <string name="no_private_messages">Ez dago erakusteko mezurik</string>
   <string name="message_hint">Idatzi mezua</string>
+  <string name="image_caption_hint">Gehitu epigrafea (aukerakoa)</string>
+  <string name="image_attach">Erantsi irudia</string>
+  <string name="image_attach_error">Ezin izan da irudia erantsi</string>
   <string name="set_contact_alias">Aldatu kontaktuaren izena</string>
   <string name="set_contact_alias_hint">Kontaktuaren izena</string>
   <string name="set_alias_button">Aldatu</string>
@@ -123,6 +126,13 @@
   <string name="dialog_title_delete_contact">Baieztatu kontaktua ezabatzea</string>
   <string name="dialog_message_delete_contact">Ziur zaude kontaktu hau eta berarekin trukatutako mezu guztiak kendu nahi dituzula?</string>
   <string name="contact_deleted_toast">Kontaktua ezabatuta</string>
+  <!--This is shown in the action bar when opening an image in fullscreen that the user sent-->
+  <string name="you">Zu</string>
+  <string name="save_image">Gorde irudia</string>
+  <string name="dialog_title_save_image">Gorde irudia?</string>
+  <string name="dialog_message_save_image">Irudi hau gordetzeak beste aplikazioei berau atzitea ahalbietuko lieke.\n\nZiur gorde nahi duzula?</string>
+  <string name="save_image_success">Irudia gorde da</string>
+  <string name="save_image_error">Ezin izan da irudia gorde</string>
   <!--Adding Contacts-->
   <string name="add_contact_title">Gehitu kontaktu bat</string>
   <string name="face_to_face">Kontaktu gisa gehitu nahi duzun pertsonarekin aurrez aurre egon behar duzu.\n\nHonek etorkizunean inork zure itxurak egitea edo zure mezuak irakurtzea eragotziko du.</string>

briar-android/src/main/res/values-fa/strings.xml

@@ -54,6 +54,7 @@
   <string name="download_briar_button">دانلود Briar (برایر) 1.0</string>
   <string name="startup_open_database">رمزگشایی سیستم ...</string>
   <string name="startup_migrate_database">به روز رسانی سیستم ...</string>
+  <string name="startup_compact_database">درحال فشرده‌سازی پایگاه داده...</string>
   <!--Navigation Drawer-->
   <string name="nav_drawer_open_description">باز کردن منوی برنامه</string>
   <string name="nav_drawer_close_description">بستن منوی برنامه</string>
@@ -121,11 +122,15 @@
   <string name="date_no_private_messages">هیچ پیامی موجود نیست</string>
   <string name="no_private_messages">هیچ پیامی برای نشان دادن وجود ندارد</string>
   <string name="message_hint">نوشتن پیام</string>
+  <string name="set_contact_alias">تغییر نام مخاطب</string>
+  <string name="set_contact_alias_hint">نام مخاطب</string>
   <string name="set_alias_button">تغییر</string>
   <string name="delete_contact">حذف مخاطب</string>
   <string name="dialog_title_delete_contact">تایید حذف مخاطب</string>
   <string name="dialog_message_delete_contact">آیا مطمئن هستید که میخواهید این مخاطب و تمام پیام های تبادل شده با آن را حذف کنید؟</string>
   <string name="contact_deleted_toast">مخاطب حذف شد</string>
+  <!--This is shown in the action bar when opening an image in fullscreen that the user sent-->
+  <string name="you">شما</string>
   <!--Adding Contacts-->
   <string name="add_contact_title">افزودن مخاطب</string>
   <string name="face_to_face">برای اضافه کردن فرد به عنوان مخاطب باید با او به صورت حضوری ملاقات کنید.
@@ -137,12 +142,12 @@
   <string name="contact_added_toast">مخاطب اضافه شد: %s</string>
   <string name="contact_already_exists">مخاطب %s از قبل وجود دارد</string>
   <string name="qr_code_invalid">کد QR نامعتبر می باشد</string>
-  <string name="qr_code_too_old">کد QR که شما اسکن کرده اید متعلق به یک نسخه قدیمی از %s می باشد.
+  <string name="qr_code_too_old">کد QR اسکن شده متعلق به یک نسخه قدیمی از %s است.
 
-لطفا از مخاطب خود بخواهید تا به آخرین نسخه آپگرید کرده و دوباره تلاش کنید.</string>
-  <string name="qr_code_too_new">کد QR که شما اسکن کرده اید متعلق به یک نسخه جدید  از %s می باشد.
+لطفا از مخاطب‌تان بخواهید تا به آخرین نسخه ارتقا داده و سپس دوباره تلاش کنید.</string>
+  <string name="qr_code_too_new">کد QR که شما اسکن کرده‌اید متعلق به یک نسخه جدیدتر  از %s است.
 
-لطفا به آخرین نسخه آپگرید کرده و دوباره تلاش کنید.</string>
+لطفا به آخرین نسخه ارتقا داده و دوباره تلاش کنید.</string>
   <string name="camera_error">خطای دوربین</string>
   <string name="connecting_to_device">اتصال به دستگاهu2026\</string>
   <string name="authenticating_with_device">تصدیق سازی با دستگاه u2026\</string>
@@ -472,6 +477,8 @@
   <!--Permission Requests-->
   <string name="permission_camera_title">دسترسی به دوربین</string>
   <string name="permission_camera_request_body">برای اسکن کردن کد QR دسترسی به دوربین لازم است.</string>
+  <string name="permission_location_title">مجوز موقعیت محل</string>
+  <string name="permission_camera_location_title">دوربین و موقعیت</string>
   <string name="permission_camera_denied_body">شما دسترسی به دوربین را رد کرده اید، اما افزودن مخاطب نیاز به دوربین دارد.
 
 لطفا اجازه دسترسی را بدهید.</string>

briar-android/src/main/res/values-fi/strings.xml

@@ -121,6 +121,8 @@
   <string name="dialog_title_delete_contact">Vahvista yhteystiedon poistaminen</string>
   <string name="dialog_message_delete_contact">Oletko varma, että haluat poistaa tämän yhteyshenkilön ja kaikki hänen kanssa vaihdetut viestit?</string>
   <string name="contact_deleted_toast">Yhteystieto poistettu</string>
+  <!--This is shown in the action bar when opening an image in fullscreen that the user sent-->
+  <string name="save_image">Tallenna kuva</string>
   <!--Adding Contacts-->
   <string name="add_contact_title">Lisää yhteystieto</string>
   <string name="face_to_face">Sinun täytyy tavata käyttäjä, jonka haluat lisätä yhteystietoihisi.\n\nTämä estää sen, että joku voisi esittää olevansa sinä tai lukea viestejäsi tulevaisuudessa</string>

briar-android/src/main/res/values-fr/strings.xml

@@ -116,12 +116,23 @@
   <string name="date_no_private_messages">Aucun message.</string>
   <string name="no_private_messages">Aucun message à afficher</string>
   <string name="message_hint">Rédiger le message</string>
+  <string name="image_caption_hint">Ajouter une légende (facultatif)</string>
+  <string name="image_attach">Joindre une image</string>
+  <string name="image_attach_error">Impossible d’attacher une image</string>
+  <string name="set_contact_alias">Changer le nom du contact</string>
   <string name="set_contact_alias_hint">Nom du contact</string>
   <string name="set_alias_button">Modifier</string>
   <string name="delete_contact">Supprimer le contact</string>
   <string name="dialog_title_delete_contact">Confirmer la suppression du contact</string>
   <string name="dialog_message_delete_contact">Voulez-vous vraiment supprimer ce contact et tous les messages associés ?</string>
   <string name="contact_deleted_toast">Le contact a été supprimé</string>
+  <!--This is shown in the action bar when opening an image in fullscreen that the user sent-->
+  <string name="you">Vous</string>
+  <string name="save_image">Enregistrer l’image</string>
+  <string name="dialog_title_save_image">Enregistrer l’image ?</string>
+  <string name="dialog_message_save_image">L’enregistrement de cette image permettra aux autres applis d’y accéder.\n\n Souhaitez-vous vraiment l’enregistrer ?</string>
+  <string name="save_image_success">L’image a été enregistrée</string>
+  <string name="save_image_error">Impossible d’enregistrer l’image</string>
   <!--Adding Contacts-->
   <string name="add_contact_title">Ajouter un contact</string>
   <string name="face_to_face">Vous devez rencontrer la personne que vous voulez ajouter comme contact, afin d’éviter que quelqu’un se fasse passer pour vous et puisse lire vos messages à l’avenir.</string>

briar-android/src/main/res/values-gl/strings.xml

@@ -116,6 +116,9 @@
   <string name="date_no_private_messages">Sen mensaxes</string>
   <string name="no_private_messages">Sen mensaxes que amosar</string>
   <string name="message_hint">Esciba unha mensaxe</string>
+  <string name="image_caption_hint">Engadir un comentario (optativo)</string>
+  <string name="image_attach">Anexar imaxe</string>
+  <string name="image_attach_error">Non se anexou a imaxe</string>
   <string name="set_contact_alias">Cambiar o nome do contacto</string>
   <string name="set_contact_alias_hint">Nome do contacto</string>
   <string name="set_alias_button">Cambiar</string>
@@ -123,6 +126,13 @@
   <string name="dialog_title_delete_contact">Confirme a eliminación do contacto</string>
   <string name="dialog_message_delete_contact">Segura de querer eliminar este contacto e todas as mensaxes que intercambiaron?</string>
   <string name="contact_deleted_toast">Contacto eliminado</string>
+  <!--This is shown in the action bar when opening an image in fullscreen that the user sent-->
+  <string name="you">Vostede</string>
+  <string name="save_image">Gardar imaxe</string>
+  <string name="dialog_title_save_image">Gardar imaxe?</string>
+  <string name="dialog_message_save_image">Ao gardar esta imaxe permitirá que outras apps teñan acceso a ela.\n\nSeguro que a quere gardar?</string>
+  <string name="save_image_success">Gardouse a imaxe</string>
+  <string name="save_image_error">Non se gardou a imaxe</string>
   <!--Adding Contacts-->
   <string name="add_contact_title">Engada un contacto</string>
   <string name="face_to_face">Debe atoparse coa persoa que quere engadir como contacto.\n\Isto evitará que calquera poida suplantala ou ler as súas mensaxes no futuro.</string>

briar-android/src/main/res/values-he/strings.xml

@@ -129,6 +129,9 @@
   <string name="date_no_private_messages">אין הודעות.</string>
   <string name="no_private_messages">אין הודעות להראות</string>
   <string name="message_hint">הקלד הודעה</string>
+  <string name="image_caption_hint">הוסף כיתוב (רשותי)</string>
+  <string name="image_attach">צרף תמונה</string>
+  <string name="image_attach_error">לא היה ניתן לצרף תמונה</string>
   <string name="set_contact_alias">שַׁנֵּה שם איש קשר</string>
   <string name="set_contact_alias_hint">שם איש הקשר</string>
   <string name="set_alias_button">שַׁנֵּה</string>
@@ -136,6 +139,13 @@
   <string name="dialog_title_delete_contact">אשר מחיקת איש קשר</string>
   <string name="dialog_message_delete_contact">האם אתה בטוח שאתה רוצה למחוק איש קשר זה ואת כל ההודעות שהוחלפו עם איש קשר זה?</string>
   <string name="contact_deleted_toast">איש קשר נמחק</string>
+  <!--This is shown in the action bar when opening an image in fullscreen that the user sent-->
+  <string name="you">אתה</string>
+  <string name="save_image">שמור תמונה</string>
+  <string name="dialog_title_save_image">לשמור תמונה?</string>
+  <string name="dialog_message_save_image">שמירת תמונה זו תאפשר ליישומים להשיג גישה אל התמונה.\n\nהאם אתה בטוח שאתה רוצה לשמור?</string>
+  <string name="save_image_success">תמונה נשמרה</string>
+  <string name="save_image_error">לא היה ניתן לשמור תמונה</string>
   <!--Adding Contacts-->
   <string name="add_contact_title">הוסף איש קשר</string>
   <string name="face_to_face">אתם חייבים להפגש עם האדם שאותו תרצו להוסיף כאיש קשר.

briar-android/src/main/res/values-hi/strings.xml

@@ -116,6 +116,9 @@
   <string name="date_no_private_messages">कोई संदेश नहीं।</string>
   <string name="no_private_messages">दिखाने के लिए कोई संदेश नहीं</string>
   <string name="message_hint">संदेश लिखें</string>
+  <string name="image_caption_hint">एक कैप्शन जोड़ें (वैकल्पिक)</string>
+  <string name="image_attach">छवि संलग्न करें</string>
+  <string name="image_attach_error">छवि संलग्न नहीं कर सका</string>
   <string name="set_contact_alias">संपर्क नाम बदलें</string>
   <string name="set_contact_alias_hint">संपर्क नाम</string>
   <string name="set_alias_button">परिवर्तन</string>
@@ -123,6 +126,13 @@
   <string name="dialog_title_delete_contact">संपर्क हटाने की पुष्टि करें</string>
   <string name="dialog_message_delete_contact">क्या आप निश्चित हैं कि आप इस संपर्क और सभी संदेशों को इस संपर्क से निकाला जाना चाहते हैं?</string>
   <string name="contact_deleted_toast">संपर्क हटा दिया गया</string>
+  <!--This is shown in the action bar when opening an image in fullscreen that the user sent-->
+  <string name="you">आप</string>
+  <string name="save_image">चित्र को सेव करें</string>
+  <string name="dialog_title_save_image">चित्र को सेव करें?</string>
+  <string name="dialog_message_save_image">इस छवि को सहेजने से अन्य ऐप्स इसे एक्सेस कर सकेंगे। \ n\ nक्या आप सुनिश्चित हैं कि आप सहेजना चाहते हैं?</string>
+  <string name="save_image_success">छवि सहेज ली गई थी</string>
+  <string name="save_image_error">छवि नहीं बचा सका</string>
   <!--Adding Contacts-->
   <string name="add_contact_title">संपर्क जोड़ना</string>
   <string name="face_to_face">आपको उस व्यक्ति के साथ मिलना चाहिए जिसे आप संपर्क के रूप में जोड़ना चाहते हैं। \ N \ n यह किसी को भविष्य में आपके प्रतिरूपण या पढ़ने के बाद से किसी को भी रोकेगा।</string>

briar-android/src/main/res/values-hu/strings.xml

@@ -121,6 +121,8 @@
   <string name="dialog_title_delete_contact">Kapcsolat törlésének megerősítése</string>
   <string name="dialog_message_delete_contact">Biztosan eltávolítja ezt a kapcsolatot és minden vele történt üzenetváltását?</string>
   <string name="contact_deleted_toast">Kapcsolat törölve</string>
+  <!--This is shown in the action bar when opening an image in fullscreen that the user sent-->
+  <string name="you">Te</string>
   <!--Adding Contacts-->
   <string name="add_contact_title">Kapcsolat hozzáadása</string>
   <string name="face_to_face">Találkoznia kell a személlyel akit, hozzá szeretne adni a kapcsolatokhoz.\n\nEz megelőzi azt, hogy valaki megszemélyesítse Önt, vagy elolvassa későbbi üzeneteit.</string>

briar-android/src/main/res/values-it/strings.xml

@@ -116,6 +116,9 @@
   <string name="date_no_private_messages">Nessun messaggio.</string>
   <string name="no_private_messages">Nessun messaggio da mostrare</string>
   <string name="message_hint">Scrivi un messaggio</string>
+  <string name="image_caption_hint">Aggiungi una didascalia (facoltativo)</string>
+  <string name="image_attach">Allega immagine</string>
+  <string name="image_attach_error">Non è stato possibile allegare l\'immagine</string>
   <string name="set_contact_alias">Cambia il nome del contatto</string>
   <string name="set_contact_alias_hint">Nome contatto</string>
   <string name="set_alias_button">Cambia</string>
@@ -123,6 +126,13 @@
   <string name="dialog_title_delete_contact">Conferma cancellazione contatto</string>
   <string name="dialog_message_delete_contact">Sei sicuro di voler rimuovere questo contatto e tutti i messaggi scambiati con esso?</string>
   <string name="contact_deleted_toast">Contatto cancellato</string>
+  <!--This is shown in the action bar when opening an image in fullscreen that the user sent-->
+  <string name="you">Tu</string>
+  <string name="save_image">Salva immagine</string>
+  <string name="dialog_title_save_image">Salvare immagine?</string>
+  <string name="dialog_message_save_image">Salvare questa immagine permetterà ad altre app di accedere ad essa.\n\nSei sicuro di volerla salvare?</string>
+  <string name="save_image_success">L\'immagine è stata salvata</string>
+  <string name="save_image_error">Non è stato possibile salvare l\'immagine</string>
   <!--Adding Contacts-->
   <string name="add_contact_title">Aggiungi un Contatto</string>
   <string name="face_to_face">Devi incontrarti con la persona che vuoi aggiungere come contatto.\n\nQuesto evita che qualcuno ti impersoni o legga i tuoi messaggi in futuro.</string>