Refactor attachment creation

briar-android/src/androidTestOfficial/java/org/briarproject/briar/android/attachment/AttachmentRetrieverIntegrationTest.java

@@ -1,4 +1,4 @@
-package org.briarproject.briar.android.conversation;
+package org.briarproject.briar.android.attachment;
 
 import android.content.res.AssetManager;
 import android.support.test.InstrumentationRegistry;
@@ -21,7 +21,7 @@ import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
 @RunWith(AndroidJUnit4.class)
-public class AttachmentControllerIntegrationTest {
+public class AttachmentRetrieverIntegrationTest {
 
 	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";
@@ -47,15 +47,15 @@ public class AttachmentControllerIntegrationTest {
 	);
 	private final MessageId msgId = new MessageId(getRandomId());
 
-	private final AttachmentController controller =
+	private final AttachmentRetriever retriever =
-			new AttachmentController(null, dimensions);
+			new AttachmentRetriever(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);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(msgId, item.getMessageId());
 		assertEquals(160, item.getWidth());
 		assertEquals(240, item.getHeight());
@@ -71,7 +71,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(originalKitten);
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(msgId, item.getMessageId());
 		assertEquals(1728, item.getWidth());
 		assertEquals(2592, item.getHeight());
@@ -87,7 +87,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/png");
 		InputStream is = getUrlInputStream(pngKitten);
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(msgId, item.getMessageId());
 		assertEquals(737, item.getWidth());
 		assertEquals(510, item.getHeight());
@@ -103,7 +103,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(uberGif);
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(1, item.getWidth());
 		assertEquals(1, item.getHeight());
 		assertEquals(dimensions.minHeight, item.getThumbnailWidth());
@@ -118,7 +118,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(lottaPixel);
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(64250, item.getWidth());
 		assertEquals(64250, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
@@ -133,7 +133,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(imageIoCrash);
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(1184, item.getWidth());
 		assertEquals(448, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
@@ -148,7 +148,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(gimpCrash);
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(1, item.getWidth());
 		assertEquals(1, item.getHeight());
 		assertEquals(dimensions.minHeight, item.getThumbnailWidth());
@@ -163,7 +163,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(optiPngAfl);
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(32, item.getWidth());
 		assertEquals(32, item.getHeight());
 		assertEquals(dimensions.minHeight, item.getThumbnailWidth());
@@ -178,7 +178,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(librawError);
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertTrue(item.hasError());
 	}
 
@@ -187,7 +187,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/gif");
 		InputStream is = getAssetInputStream("animated.gif");
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(65535, item.getWidth());
 		assertEquals(65535, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
@@ -202,7 +202,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/gif");
 		InputStream is = getAssetInputStream("animated2.gif");
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(10000, item.getWidth());
 		assertEquals(10000, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
@@ -217,7 +217,7 @@ public class AttachmentControllerIntegrationTest {
 		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);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(16384, item.getWidth());
 		assertEquals(16384, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
@@ -232,7 +232,7 @@ public class AttachmentControllerIntegrationTest {
 		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);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(1, item.getWidth());
 		assertEquals(10000, item.getHeight());
 		assertEquals(dimensions.minWidth, item.getThumbnailWidth());
@@ -247,7 +247,7 @@ public class AttachmentControllerIntegrationTest {
 		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);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(1920, item.getWidth());
 		assertEquals(1, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());

briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentCreationTask.java

@@ -0,0 +1,114 @@
+package org.briarproject.briar.android.attachment;
+
+import android.content.ContentResolver;
+import android.net.Uri;
+import android.support.annotation.Nullable;
+
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.briar.api.messaging.AttachmentHeader;
+import org.briarproject.briar.api.messaging.MessagingManager;
+import org.jsoup.UnsupportedMimeTypeException;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.List;
+import java.util.logging.Logger;
+
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+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.api.messaging.MessagingConstants.IMAGE_MIME_TYPES;
+
+@NotNullByDefault
+class AttachmentCreationTask {
+
+	private static Logger LOG =
+			getLogger(AttachmentCreationTask.class.getName());
+
+	private final MessagingManager messagingManager;
+	private final ContentResolver contentResolver;
+	private final GroupId groupId;
+	private final List<Uri> uris;
+	private final boolean needsSize;
+	@Nullable
+	private AttachmentCreator attachmentCreator;
+
+	private volatile boolean canceled = false;
+
+	AttachmentCreationTask(MessagingManager messagingManager,
+			ContentResolver contentResolver,
+			AttachmentCreator attachmentCreator, GroupId groupId,
+			List<Uri> uris, boolean needsSize) {
+		this.messagingManager = messagingManager;
+		this.contentResolver = contentResolver;
+		this.groupId = groupId;
+		this.uris = uris;
+		this.needsSize = needsSize;
+		this.attachmentCreator = attachmentCreator;
+	}
+
+	public void cancel() {
+		canceled = true;
+		attachmentCreator = null;
+	}
+
+	@IoExecutor
+	public void storeAttachments() {
+		for (Uri uri: uris) processUri(uri);
+		if (!canceled && attachmentCreator != null)
+			attachmentCreator.onAttachmentCreationFinished();
+		attachmentCreator = null;
+	}
+
+	@IoExecutor
+	private void processUri(Uri uri) {
+		if (canceled) return;
+		try {
+			AttachmentHeader h = storeAttachment(uri);
+			if (attachmentCreator != null) {
+				attachmentCreator
+						.onAttachmentHeaderReceived(uri, h, needsSize);
+			}
+		} catch (DbException | IOException e) {
+			logException(LOG, WARNING, e);
+			if (attachmentCreator != null) {
+				attachmentCreator.onAttachmentError(uri, e);
+				canceled = true;
+			}
+		}
+	}
+
+	@IoExecutor
+	private AttachmentHeader storeAttachment(Uri uri)
+			throws IOException, DbException {
+		long start = now();
+		String contentType = contentResolver.getType(uri);
+		if (contentType == null) throw new IOException("null content type");
+		if (!isValidMimeType(contentType))
+			throw new UnsupportedMimeTypeException("", contentType,
+					uri.toString());
+		InputStream is = contentResolver.openInputStream(uri);
+		if (is == null) throw new IOException();
+		long timestamp = System.currentTimeMillis();
+		AttachmentHeader h = messagingManager
+				.addLocalAttachment(groupId, timestamp, contentType, is);
+		tryToClose(is, LOG, WARNING);
+		logDuration(LOG, "Storing attachment", start);
+		return h;
+	}
+
+	private boolean isValidMimeType(@Nullable String mimeType) {
+		if (mimeType == null) return false;
+		for (String supportedType : IMAGE_MIME_TYPES) {
+			if (supportedType.equals(mimeType)) return true;
+		}
+		return false;
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentCreator.java

@@ -0,0 +1,206 @@
+package org.briarproject.briar.android.attachment;
+
+
+import android.app.Application;
+import android.arch.lifecycle.LiveData;
+import android.arch.lifecycle.MutableLiveData;
+import android.net.Uri;
+import android.support.annotation.Nullable;
+import android.support.annotation.UiThread;
+
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.briar.R;
+import org.briarproject.briar.api.messaging.Attachment;
+import org.briarproject.briar.api.messaging.AttachmentHeader;
+import org.briarproject.briar.api.messaging.FileTooBigException;
+import org.briarproject.briar.api.messaging.MessagingManager;
+import org.jsoup.UnsupportedMimeTypeException;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import static java.util.Objects.requireNonNull;
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.briar.api.messaging.MessagingConstants.MAX_IMAGE_SIZE;
+
+@NotNullByDefault
+public class AttachmentCreator {
+
+	private static Logger LOG = getLogger(AttachmentCreator.class.getName());
+
+	private final Application app;
+	@IoExecutor
+	private final Executor ioExecutor;
+	private final MessagingManager messagingManager;
+	private final AttachmentRetriever controller;
+
+	private final Map<Uri, AttachmentItem> unsentItems =
+			new ConcurrentHashMap<>();
+	private final Map<Uri, MutableLiveData<AttachmentItemResult>>
+			liveDataResult = new ConcurrentHashMap<>();
+
+	@Nullable
+	private MutableLiveData<Boolean> liveDataFinished = null;
+	@Nullable
+	private AttachmentCreationTask task;
+
+	public AttachmentCreator(Application app, @IoExecutor Executor ioExecutor,
+			MessagingManager messagingManager,
+			AttachmentRetriever controller) {
+		this.app = app;
+		this.ioExecutor = ioExecutor;
+		this.messagingManager = messagingManager;
+		this.controller = controller;
+	}
+
+	@UiThread
+	public AttachmentResult storeAttachments(GroupId groupId,
+			Collection<Uri> uris) {
+		if (task != null && !isStoring()) throw new AssertionError();
+		List<LiveData<AttachmentItemResult>> itemResults = new ArrayList<>();
+		List<Uri> urisToStore = new ArrayList<>();
+		for (Uri uri : uris) {
+			MutableLiveData<AttachmentItemResult> liveData =
+					new MutableLiveData<>();
+			itemResults.add(liveData);
+			liveDataResult.put(uri, liveData);
+			if (unsentItems.containsKey(uri)) {
+				// This can happen due to configuration changes.
+				// So don't create a new attachment, if we have one already.
+				AttachmentItem item = requireNonNull(unsentItems.get(uri));
+				AttachmentItemResult result =
+						new AttachmentItemResult(uri, item);
+				liveData.setValue(result);
+			} else {
+				urisToStore.add(uri);
+			}
+		}
+		boolean needsSize = uris.size() == 1;
+		task = new AttachmentCreationTask(messagingManager,
+				app.getContentResolver(), this, groupId, urisToStore,
+				needsSize);
+		ioExecutor.execute(() -> task.storeAttachments());
+		liveDataFinished = new MutableLiveData<>();
+		return new AttachmentResult(itemResults, liveDataFinished);
+	}
+
+	@IoExecutor
+	void onAttachmentHeaderReceived(Uri uri, AttachmentHeader h,
+			boolean needsSize) {
+		// get and cache AttachmentItem for ImagePreview
+		try {
+			Attachment a = controller.getMessageAttachment(h);
+			AttachmentItem item = controller.getAttachmentItem(h, a, needsSize);
+			if (item.hasError()) throw new IOException();
+			unsentItems.put(uri, item);
+			MutableLiveData<AttachmentItemResult> result =
+					liveDataResult.get(uri);
+			if (result != null) {  // might have been cleared on UiThread
+				result.postValue(new AttachmentItemResult(uri, item));
+			}
+		} catch (IOException | DbException e) {
+			logException(LOG, WARNING, e);
+			onAttachmentError(uri, e);
+		}
+	}
+
+	@IoExecutor
+	void onAttachmentError(Uri uri, Throwable t) {
+		String errorMsg;
+		if (t instanceof UnsupportedMimeTypeException) {
+			String mimeType = ((UnsupportedMimeTypeException) t).getMimeType();
+			errorMsg = app.getString(
+					R.string.image_attach_error_invalid_mime_type, mimeType);
+		} else if (t instanceof FileTooBigException) {
+			int mb = MAX_IMAGE_SIZE / 1024 / 1024;
+			errorMsg = app.getString(R.string.image_attach_error_too_big, mb);
+		} else {
+			errorMsg = null; // generic error
+		}
+		MutableLiveData<AttachmentItemResult> result = liveDataResult.get(uri);
+		if (result != null)
+			result.postValue(new AttachmentItemResult(errorMsg));
+		// expect to receive a cancel from the UI
+	}
+
+	@IoExecutor
+	void onAttachmentCreationFinished() {
+		if (liveDataFinished != null) liveDataFinished.postValue(true);
+	}
+
+	@UiThread
+	public List<AttachmentHeader> getAttachmentHeadersForSending() {
+		List<AttachmentHeader> headers =
+				new ArrayList<>(unsentItems.values().size());
+		for (AttachmentItem item : unsentItems.values()) {
+			headers.add(item.getHeader());
+		}
+		return headers;
+	}
+
+	/**
+	 * Marks the attachments as sent and adds the items to the cache for display
+	 *
+	 * @param id The MessageId of the sent message.
+	 */
+	public void onAttachmentsSent(MessageId id) {
+		controller.cachePut(id, new ArrayList<>(unsentItems.values()));
+		resetState();
+	}
+
+	@UiThread
+	public void cancel() {
+		if (task == null) throw new AssertionError();
+		task.cancel();
+		// let observers know that they can remove themselves
+		for (MutableLiveData<AttachmentItemResult> liveData : liveDataResult
+				.values()) {
+			if (liveData.getValue() == null) {
+				liveData.setValue(null);
+			}
+		}
+		if (liveDataFinished != null) liveDataFinished.setValue(false);
+		deleteUnsentAttachments();
+		resetState();
+	}
+
+	@UiThread
+	private void resetState() {
+		task = null;
+		liveDataResult.clear();
+		liveDataFinished = null;
+		unsentItems.clear();
+	}
+
+	@UiThread
+	public void deleteUnsentAttachments() {
+		List<AttachmentItem> itemsToDelete =
+				new ArrayList<>(unsentItems.values());
+		ioExecutor.execute(() -> {
+			for (AttachmentItem item : itemsToDelete) {
+				try {
+					messagingManager.removeAttachment(item.getHeader());
+				} catch (DbException e) {
+					logException(LOG, WARNING, e);
+				}
+			}
+		});
+	}
+
+	private boolean isStoring() {
+		return liveDataFinished != null;
+	}
+
+}

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

@@ -1,11 +1,16 @@
-package org.briarproject.briar.android.conversation;
+package org.briarproject.briar.android.attachment;
 
 import android.content.res.Resources;
 import android.support.annotation.VisibleForTesting;
 
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
 
-class AttachmentDimensions {
+import javax.annotation.concurrent.Immutable;
+
+@Immutable
+@NotNullByDefault
+public class AttachmentDimensions {
 
 	final int defaultSize;
 	final int minWidth, maxWidth;
@@ -21,7 +26,7 @@ class AttachmentDimensions {
 		this.maxHeight = maxHeight;
 	}
 
-	static AttachmentDimensions getAttachmentDimensions(Resources res) {
+	public static AttachmentDimensions getAttachmentDimensions(Resources res) {
 		int defaultSize =
 				res.getDimensionPixelSize(R.dimen.message_bubble_image_default);
 		int minWidth = res.getDimensionPixelSize(
@@ -33,7 +38,7 @@ class AttachmentDimensions {
 		int maxHeight = res.getDimensionPixelSize(
 				R.dimen.message_bubble_image_max_height);
 		return new AttachmentDimensions(defaultSize, minWidth, maxWidth,
-				minHeight, minHeight);
+				minHeight, maxHeight);
 	}
 
 }

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

@@ -1,4 +1,4 @@
-package org.briarproject.briar.android.conversation;
+package org.briarproject.briar.android.attachment;
 
 import android.os.Parcel;
 import android.os.Parcelable;
@@ -12,6 +12,8 @@ import java.util.concurrent.atomic.AtomicLong;
 
 import javax.annotation.concurrent.Immutable;
 
+import static java.util.Objects.requireNonNull;
+
 @Immutable
 @NotNullByDefault
 public class AttachmentItem implements Parcelable {
@@ -57,8 +59,8 @@ public class AttachmentItem implements Parcelable {
 		MessageId messageId = new MessageId(messageIdByte);
 		width = in.readInt();
 		height = in.readInt();
-		String mimeType = in.readString();
+		String mimeType = requireNonNull(in.readString());
-		extension = in.readString();
+		extension = requireNonNull(in.readString());
 		thumbnailWidth = in.readInt();
 		thumbnailHeight = in.readInt();
 		hasError = in.readByte() != 0;
@@ -82,27 +84,27 @@ public class AttachmentItem implements Parcelable {
 		return height;
 	}
 
-	String getMimeType() {
+	public String getMimeType() {
 		return header.getContentType();
 	}
 
-	String getExtension() {
+	public String getExtension() {
 		return extension;
 	}
 
-	int getThumbnailWidth() {
+	public int getThumbnailWidth() {
 		return thumbnailWidth;
 	}
 
-	int getThumbnailHeight() {
+	public int getThumbnailHeight() {
 		return thumbnailHeight;
 	}
 
-	boolean hasError() {
+	public boolean hasError() {
 		return hasError;
 	}
 
-	String getTransitionName() {
+	public String getTransitionName() {
 		return String.valueOf(instanceId);
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentItemResult.java

@@ -1,4 +1,4 @@
-package org.briarproject.briar.android.conversation;
+package org.briarproject.briar.android.attachment;
 
 import android.net.Uri;
 
@@ -9,7 +9,7 @@ import javax.annotation.concurrent.Immutable;
 
 @Immutable
 @NotNullByDefault
-public class AttachmentResult {
+public class AttachmentItemResult {
 
 	@Nullable
 	private final Uri uri;
@@ -18,13 +18,13 @@ public class AttachmentResult {
 	@Nullable
 	private final String errorMsg;
 
-	public AttachmentResult(Uri uri, AttachmentItem item) {
+	public AttachmentItemResult(Uri uri, AttachmentItem item) {
 		this.uri = uri;
 		this.item = item;
 		this.errorMsg = null;
 	}
 
-	public AttachmentResult(@Nullable String errorMsg) {
+	public AttachmentItemResult(@Nullable String errorMsg) {
 		this.uri = null;
 		this.item = null;
 		this.errorMsg = errorMsg;

briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentManager.java

@@ -0,0 +1,20 @@
+package org.briarproject.briar.android.attachment;
+
+import android.net.Uri;
+import android.support.annotation.UiThread;
+
+import org.briarproject.briar.api.messaging.AttachmentHeader;
+
+import java.util.Collection;
+import java.util.List;
+
+@UiThread
+public interface AttachmentManager{
+
+	AttachmentResult storeAttachments(Collection<Uri> uri);
+
+	List<AttachmentHeader> getAttachmentHeadersForSending();
+
+	void cancel();
+
+}

briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentResult.java

@@ -0,0 +1,33 @@
+package org.briarproject.briar.android.attachment;
+
+import android.arch.lifecycle.LiveData;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.util.Collection;
+
+import javax.annotation.concurrent.Immutable;
+
+@Immutable
+@NotNullByDefault
+public class AttachmentResult {
+
+	private final Collection<LiveData<AttachmentItemResult>> itemResults;
+	private final LiveData<Boolean> finished;
+
+	public AttachmentResult(
+			Collection<LiveData<AttachmentItemResult>> itemResults,
+			LiveData<Boolean> finished) {
+		this.itemResults = itemResults;
+		this.finished = finished;
+	}
+
+	public Collection<LiveData<AttachmentItemResult>> getItemResults() {
+		return itemResults;
+	}
+
+	public LiveData<Boolean> getFinished() {
+		return finished;
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentRetriever.java

@@ -1,9 +1,7 @@
-package org.briarproject.briar.android.conversation;
+package org.briarproject.briar.android.attachment;
 
-import android.content.ContentResolver;
 import android.graphics.BitmapFactory;
 import android.graphics.BitmapFactory.Options;
-import android.net.Uri;
 import android.support.annotation.Nullable;
 import android.support.annotation.VisibleForTesting;
 import android.support.media.ExifInterface;
@@ -15,9 +13,8 @@ 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.GroupId;
 import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.briar.android.conversation.ImageHelper.DecodeResult;
+import org.briarproject.briar.android.attachment.ImageHelper.DecodeResult;
 import org.briarproject.briar.api.messaging.Attachment;
 import org.briarproject.briar.api.messaging.AttachmentHeader;
 import org.briarproject.briar.api.messaging.MessagingManager;
@@ -38,20 +35,18 @@ import static android.support.media.ExifInterface.ORIENTATION_TRANSVERSE;
 import static android.support.media.ExifInterface.TAG_IMAGE_LENGTH;
 import static android.support.media.ExifInterface.TAG_IMAGE_WIDTH;
 import static android.support.media.ExifInterface.TAG_ORIENTATION;
-import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
 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.api.messaging.MessagingConstants.IMAGE_MIME_TYPES;
 
 @NotNullByDefault
-class AttachmentController {
+public class AttachmentRetriever {
 
 	private static final Logger LOG =
-			getLogger(AttachmentController.class.getName());
+			getLogger(AttachmentRetriever.class.getName());
 	private static final int READ_LIMIT = 1024 * 8192;
 
 	private final MessagingManager messagingManager;
@@ -60,12 +55,11 @@ class AttachmentController {
 	private final int minWidth, maxWidth;
 	private final int minHeight, maxHeight;
 
-	private final Map<Uri, AttachmentItem> unsentItems =
-			new ConcurrentHashMap<>();
 	private final Map<MessageId, List<AttachmentItem>> attachmentCache =
 			new ConcurrentHashMap<>();
 
-	AttachmentController(MessagingManager messagingManager,
+	@VisibleForTesting
+	AttachmentRetriever(MessagingManager messagingManager,
 			AttachmentDimensions dimensions, ImageHelper imageHelper) {
 		this.messagingManager = messagingManager;
 		this.imageHelper = imageHelper;
@@ -76,7 +70,7 @@ class AttachmentController {
 		maxHeight = dimensions.maxHeight;
 	}
 
-	AttachmentController(MessagingManager messagingManager,
+	public AttachmentRetriever(MessagingManager messagingManager,
 			AttachmentDimensions dimensions) {
 		this(messagingManager, dimensions, new ImageHelper() {
 			@Override
@@ -99,17 +93,17 @@ class AttachmentController {
 		});
 	}
 
-	void put(MessageId messageId, List<AttachmentItem> attachments) {
+	public void cachePut(MessageId messageId, List<AttachmentItem> attachments) {
 		attachmentCache.put(messageId, attachments);
 	}
 
 	@Nullable
-	List<AttachmentItem> get(MessageId messageId) {
+	public List<AttachmentItem> cacheGet(MessageId messageId) {
 		return attachmentCache.get(messageId);
 	}
 
 	@DatabaseExecutor
-	List<Pair<AttachmentHeader, Attachment>> getMessageAttachments(
+	public List<Pair<AttachmentHeader, Attachment>> getMessageAttachments(
 			List<AttachmentHeader> headers) throws DbException {
 		long start = now();
 		List<Pair<AttachmentHeader, Attachment>> attachments =
@@ -118,86 +112,13 @@ class AttachmentController {
 			Attachment a = messagingManager.getAttachment(h.getMessageId());
 			attachments.add(new Pair<>(h, a));
 		}
-		logDuration(LOG, "Loading attachment", start);
+		logDuration(LOG, "Loading attachments", start);
 		return attachments;
 	}
 
 	@DatabaseExecutor
-	AttachmentItem createAttachmentHeader(ContentResolver contentResolver,
+	Attachment getMessageAttachment(AttachmentHeader h) throws DbException {
-			GroupId groupId, Uri uri, boolean needsSize)
+		return messagingManager.getAttachment(h.getMessageId());
-			throws IOException, DbException {
-		if (unsentItems.containsKey(uri)) {
-			// This can happen due to configuration (screen orientation) change.
-			// So don't create a new attachment, if we have one already.
-			return requireNonNull(unsentItems.get(uri));
-		}
-		long start = now();
-		InputStream is = contentResolver.openInputStream(uri);
-		if (is == null) throw new IOException();
-		String contentType = contentResolver.getType(uri);
-		if (contentType == null) throw new IOException("null content type");
-		long timestamp = System.currentTimeMillis();
-		AttachmentHeader h = messagingManager
-				.addLocalAttachment(groupId, timestamp, contentType, is);
-		tryToClose(is, LOG, WARNING);
-		logDuration(LOG, "Storing attachment", start);
-		// get and store AttachmentItem for ImagePreview
-		AttachmentItem item =
-				getAttachmentItem(contentResolver, uri, h, needsSize);
-		if (item.hasError()) throw new IOException();
-		unsentItems.put(uri, item);
-		return item;
-	}
-
-	boolean isValidMimeType(@Nullable String mimeType) {
-		if (mimeType == null) return false;
-		for (String supportedType : IMAGE_MIME_TYPES) {
-			if (supportedType.equals(mimeType)) return true;
-		}
-		return false;
-	}
-
-	@DatabaseExecutor
-	void deleteUnsentAttachments() {
-		for (AttachmentItem item : unsentItems.values()) {
-			try {
-				messagingManager.removeAttachment(item.getHeader());
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-			}
-		}
-		unsentItems.clear();
-	}
-
-	List<AttachmentHeader> getUnsentAttachmentHeaders() {
-		List<AttachmentHeader> headers =
-				new ArrayList<>(unsentItems.values().size());
-		for (AttachmentItem item : unsentItems.values()) {
-			headers.add(item.getHeader());
-		}
-		return headers;
-	}
-
-	/**
-	 * Marks the attachments as sent and adds the items to the cache for display
-	 * @param id The MessageId of the sent message.
-	 */
-	void onAttachmentsSent(MessageId id) {
-		attachmentCache.put(id, new ArrayList<>(unsentItems.values()));
-		unsentItems.clear();
-	}
-
-	@DatabaseExecutor
-	private AttachmentItem getAttachmentItem(ContentResolver contentResolver,
-			Uri uri, AttachmentHeader h, boolean needsSize) throws IOException {
-		InputStream is = null;
-		try {
-			is = contentResolver.openInputStream(uri);
-			if (is == null) throw new IOException();
-			return getAttachmentItem(h, new Attachment(is), needsSize);
-		} finally {
-			if (is != null) tryToClose(is, LOG, WARNING);
-		}
 	}
 
 	/**
@@ -205,7 +126,7 @@ class AttachmentController {
 	 * <p>
 	 * Note: This closes the {@link Attachment}'s {@link InputStream}.
 	 */
-	List<AttachmentItem> getAttachmentItems(
+	public List<AttachmentItem> getAttachmentItems(
 			List<Pair<AttachmentHeader, Attachment>> attachments) {
 		boolean needsSize = attachments.size() == 1;
 		List<AttachmentItem> items = new ArrayList<>(attachments.size());
@@ -221,7 +142,6 @@ class AttachmentController {
 	 * Creates an {@link AttachmentItem} from the {@link Attachment}'s
 	 * {@link InputStream} which will be closed when this method returns.
 	 */
-	@VisibleForTesting
 	AttachmentItem getAttachmentItem(AttachmentHeader h, Attachment a,
 			boolean needsSize) {
 		if (!needsSize) {

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

@@ -1,4 +1,4 @@
-package org.briarproject.briar.android.conversation;
+package org.briarproject.briar.android.attachment;
 
 import android.support.annotation.Nullable;
 

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

@@ -52,6 +52,8 @@ import org.briarproject.bramble.api.sync.event.MessagesSentEvent;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.activity.BriarActivity;
+import org.briarproject.briar.android.attachment.AttachmentItem;
+import org.briarproject.briar.android.attachment.AttachmentRetriever;
 import org.briarproject.briar.android.blog.BlogActivity;
 import org.briarproject.briar.android.conversation.ConversationVisitor.AttachmentCache;
 import org.briarproject.briar.android.conversation.ConversationVisitor.TextCache;
@@ -183,7 +185,7 @@ public class ConversationActivity extends BriarActivity
 		loadMessages();
 	};
 
-	private AttachmentController attachmentController;
+	private AttachmentRetriever attachmentRetriever;
 	private ConversationViewModel viewModel;
 	private ConversationVisitor visitor;
 	private ConversationAdapter adapter;
@@ -218,7 +220,7 @@ public class ConversationActivity extends BriarActivity
 
 		viewModel = ViewModelProviders.of(this, viewModelFactory)
 				.get(ConversationViewModel.class);
-		attachmentController = viewModel.getAttachmentController();
+		attachmentRetriever = viewModel.getAttachmentRetriever();
 
 		setContentView(R.layout.activity_conversation);
 
@@ -456,13 +458,13 @@ public class ConversationActivity extends BriarActivity
 		// 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);
+			List<AttachmentItem> items = attachmentRetriever.cacheGet(id);
 			if (items == null) {
 				LOG.info("Eagerly loading image size for latest message");
-				items = attachmentController.getAttachmentItems(
+				items = attachmentRetriever.getAttachmentItems(
-						attachmentController.getMessageAttachments(
+						attachmentRetriever.getMessageAttachments(
 								h.getAttachmentHeaders()));
-				attachmentController.put(id, items);
+				attachmentRetriever.cachePut(id, items);
 			}
 		}
 	}
@@ -544,10 +546,10 @@ public class ConversationActivity extends BriarActivity
 		runOnDbThread(() -> {
 			try {
 				List<Pair<AttachmentHeader, Attachment>> attachments =
-						attachmentController.getMessageAttachments(headers);
+						attachmentRetriever.getMessageAttachments(headers);
 				// TODO move getting the items off to IoExecutor, if size == 1
 				List<AttachmentItem> items =
-						attachmentController.getAttachmentItems(attachments);
+						attachmentRetriever.getAttachmentItems(attachments);
 				displayMessageAttachments(messageId, items);
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
@@ -558,7 +560,7 @@ public class ConversationActivity extends BriarActivity
 	private void displayMessageAttachments(MessageId m,
 			List<AttachmentItem> items) {
 		runOnUiThreadUnlessDestroyed(() -> {
-			attachmentController.put(m, items);
+			attachmentRetriever.cachePut(m, items);
 			Pair<Integer, ConversationMessageItem> pair =
 					adapter.getMessageItem(m);
 			if (pair != null) {
@@ -903,7 +905,7 @@ public class ConversationActivity extends BriarActivity
 	@Override
 	public List<AttachmentItem> getAttachmentItems(MessageId m,
 			List<AttachmentHeader> headers) {
-		List<AttachmentItem> attachments = attachmentController.get(m);
+		List<AttachmentItem> attachments = attachmentRetriever.cacheGet(m);
 		if (attachments == null) {
 			loadMessageAttachments(m, headers);
 			return emptyList();

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

@@ -4,6 +4,7 @@ import android.support.annotation.UiThread;
 import android.view.View;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.briar.android.attachment.AttachmentItem;
 
 @UiThread
 @NotNullByDefault

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

@@ -3,6 +3,7 @@ package org.briarproject.briar.android.conversation;
 import android.support.annotation.LayoutRes;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.briar.android.attachment.AttachmentItem;
 import org.briarproject.briar.api.messaging.PrivateMessageHeader;
 
 import java.util.List;

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

@@ -9,6 +9,7 @@ import android.view.ViewGroup;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
+import org.briarproject.briar.android.attachment.AttachmentItem;
 
 import static android.support.constraint.ConstraintSet.WRAP_CONTENT;
 import static android.support.v4.content.ContextCompat.getColor;

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

@@ -5,7 +5,6 @@ import android.arch.lifecycle.AndroidViewModel;
 import android.arch.lifecycle.LiveData;
 import android.arch.lifecycle.MutableLiveData;
 import android.arch.lifecycle.Transformations;
-import android.content.ContentResolver;
 import android.net.Uri;
 import android.support.annotation.Nullable;
 import android.support.annotation.UiThread;
@@ -20,26 +19,26 @@ import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.NoSuchContactException;
 import org.briarproject.bramble.api.db.TransactionManager;
 import org.briarproject.bramble.api.identity.AuthorId;
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
 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.bramble.api.sync.MessageId;
-import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.briar.android.attachment.AttachmentCreator;
-import org.briarproject.briar.R;
+import org.briarproject.briar.android.attachment.AttachmentManager;
+import org.briarproject.briar.android.attachment.AttachmentResult;
+import org.briarproject.briar.android.attachment.AttachmentRetriever;
 import org.briarproject.briar.android.util.UiUtils;
-import org.briarproject.briar.android.view.TextAttachmentController.AttachmentManager;
 import org.briarproject.briar.android.viewmodel.LiveEvent;
 import org.briarproject.briar.android.viewmodel.MutableLiveEvent;
 import org.briarproject.briar.api.messaging.AttachmentHeader;
-import org.briarproject.briar.api.messaging.FileTooBigException;
 import org.briarproject.briar.api.messaging.MessagingManager;
 import org.briarproject.briar.api.messaging.PrivateMessage;
 import org.briarproject.briar.api.messaging.PrivateMessageFactory;
 import org.briarproject.briar.api.messaging.PrivateMessageHeader;
 
-import java.io.IOException;
 import java.util.Collection;
 import java.util.List;
 import java.util.concurrent.Executor;
@@ -53,14 +52,12 @@ import static java.util.logging.Logger.getLogger;
 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.attachment.AttachmentDimensions.getAttachmentDimensions;
 import static org.briarproject.briar.android.settings.SettingsFragment.SETTINGS_NAMESPACE;
-import static org.briarproject.briar.android.util.UiUtils.observeForeverOnce;
-import static org.briarproject.briar.api.messaging.MessagingConstants.MAX_IMAGE_SIZE;
 
 @NotNullByDefault
-public class ConversationViewModel extends AndroidViewModel implements
+public class ConversationViewModel extends AndroidViewModel
-		AttachmentManager {
+		implements AttachmentManager {
 
 	private static Logger LOG =
 			getLogger(ConversationViewModel.class.getName());
@@ -78,10 +75,13 @@ public class ConversationViewModel extends AndroidViewModel implements
 	private final ContactManager contactManager;
 	private final SettingsManager settingsManager;
 	private final PrivateMessageFactory privateMessageFactory;
-	private final AttachmentController attachmentController;
+	private final AttachmentRetriever attachmentRetriever;
+	private final AttachmentCreator attachmentCreator;
 
 	@Nullable
 	private ContactId contactId = null;
+	@Nullable
+	private volatile GroupId messagingGroupId = null;
 	private final MutableLiveData<Contact> contact = new MutableLiveData<>();
 	private final LiveData<AuthorId> contactAuthorId =
 			Transformations.map(contact, c -> c.getAuthor().getId());
@@ -97,15 +97,14 @@ public class ConversationViewModel extends AndroidViewModel implements
 			new MutableLiveData<>();
 	private final MutableLiveData<Boolean> contactDeleted =
 			new MutableLiveData<>();
-	private final MutableLiveData<GroupId> messagingGroupId =
-			new MutableLiveData<>();
 	private final MutableLiveData<PrivateMessageHeader> addedHeader =
 			new MutableLiveData<>();
 
 	@Inject
 	ConversationViewModel(Application application,
 			@DatabaseExecutor Executor dbExecutor,
-			@CryptoExecutor Executor cryptoExecutor, TransactionManager db,
+			@CryptoExecutor Executor cryptoExecutor,
+			@IoExecutor Executor ioExecutor, TransactionManager db,
 			MessagingManager messagingManager, ContactManager contactManager,
 			SettingsManager settingsManager,
 			PrivateMessageFactory privateMessageFactory) {
@@ -117,15 +116,17 @@ public class ConversationViewModel extends AndroidViewModel implements
 		this.contactManager = contactManager;
 		this.settingsManager = settingsManager;
 		this.privateMessageFactory = privateMessageFactory;
-		this.attachmentController = new AttachmentController(messagingManager,
+		this.attachmentRetriever = new AttachmentRetriever(messagingManager,
 				getAttachmentDimensions(application.getResources()));
+		this.attachmentCreator = new AttachmentCreator(getApplication(),
+				ioExecutor, messagingManager, attachmentRetriever);
 		contactDeleted.setValue(false);
 	}
 
 	@Override
 	protected void onCleared() {
 		super.onCleared();
-		attachmentController.deleteUnsentAttachments();
+		attachmentCreator.deleteUnsentAttachments();
 	}
 
 	/**
@@ -149,6 +150,10 @@ public class ConversationViewModel extends AndroidViewModel implements
 				contact.postValue(c);
 				logDuration(LOG, "Loading contact", start);
 				start = now();
+				messagingGroupId =
+						messagingManager.getConversationId(contactId);
+				logDuration(LOG, "Load conversation GroupId", start);
+				start = now();
 				checkFeaturesAndOnboarding(contactId);
 				logDuration(LOG, "Checking for image support", start);
 			} catch (NoSuchContactException e) {
@@ -185,73 +190,29 @@ public class ConversationViewModel extends AndroidViewModel implements
 
 	void sendMessage(@Nullable String text,
 			List<AttachmentHeader> attachmentHeaders, long timestamp) {
-		if (messagingGroupId.getValue() == null) loadGroupId();
+		GroupId groupId = messagingGroupId;
-		observeForeverOnce(messagingGroupId, groupId -> {
+		if (groupId == null) throw new IllegalStateException();
-			if (groupId == null) return;
+		createMessage(groupId, text, attachmentHeaders, timestamp);
-			createMessage(groupId, text, attachmentHeaders, timestamp);
-		});
 	}
 
 	@Override
-	public LiveData<AttachmentResult> storeAttachment(Uri uri,
+	@UiThread
-			boolean needsSize) {
+	public AttachmentResult storeAttachments(Collection<Uri> uris) {
-		// use LiveData to not keep references to view scope
+		GroupId groupId = messagingGroupId;
-		MutableLiveData<AttachmentResult> result = new MutableLiveData<>();
+		if (groupId == null) throw new IllegalStateException();
-		// check first if mime type is supported
+		return attachmentCreator.storeAttachments(groupId, uris);
-		ContentResolver contentResolver =
-				getApplication().getContentResolver();
-		String mimeType = contentResolver.getType(uri);
-		if (!attachmentController.isValidMimeType(mimeType)) {
-			String errorMsg = getApplication().getString(
-					R.string.image_attach_error_invalid_mime_type, mimeType);
-			result.setValue(new AttachmentResult(errorMsg));
-			return result;
-		}
-		if (messagingGroupId.getValue() == null) loadGroupId();
-		observeForeverOnce(messagingGroupId, groupId -> dbExecutor.execute(()
-				-> {
-			if (groupId == null) throw new IllegalStateException();
-			long start = now();
-			try {
-				AttachmentItem item = attachmentController
-						.createAttachmentHeader(contentResolver, groupId, uri,
-								needsSize);
-				result.postValue(new AttachmentResult(uri, item));
-			} catch(FileTooBigException e) {
-				logException(LOG, WARNING, e);
-				int mb = MAX_IMAGE_SIZE / 1024 / 1024;
-				String errorMsg = getApplication()
-						.getString(R.string.image_attach_error_too_big, mb);
-				result.postValue(new AttachmentResult(errorMsg));
-			} catch (DbException | IOException e) {
-				logException(LOG, WARNING, e);
-				result.postValue(new AttachmentResult(null));
-			}
-			logDuration(LOG, "Storing attachment", start);
-		}));
-		return result;
 	}
 
 	@Override
-	public List<AttachmentHeader> getAttachmentHeaders() {
+	@UiThread
-		return attachmentController.getUnsentAttachmentHeaders();
+	public List<AttachmentHeader> getAttachmentHeadersForSending() {
+		return attachmentCreator.getAttachmentHeadersForSending();
 	}
 
 	@Override
-	public void removeAttachments() {
+	@UiThread
-		dbExecutor.execute(attachmentController::deleteUnsentAttachments);
+	public void cancel() {
-	}
+		attachmentCreator.cancel();
-
-	private void loadGroupId() {
-		if (contactId == null) throw new IllegalStateException();
-		dbExecutor.execute(() -> {
-			try {
-				messagingGroupId.postValue(
-						messagingManager.getConversationId(contactId));
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-			}
-		});
 	}
 
 	@DatabaseExecutor
@@ -337,7 +298,7 @@ public class ConversationViewModel extends AndroidViewModel implements
 						message.getId(), message.getGroupId(),
 						message.getTimestamp(), true, true, false, false,
 						text != null, attachments);
-				attachmentController.onAttachmentsSent(m.getMessage().getId());
+				attachmentCreator.onAttachmentsSent(m.getMessage().getId());
 				// TODO add text to cache when available here
 				addedHeader.postValue(h);
 			} catch (DbException e) {
@@ -351,8 +312,8 @@ public class ConversationViewModel extends AndroidViewModel implements
 		addedHeader.setValue(null);
 	}
 
-	AttachmentController getAttachmentController() {
+	AttachmentRetriever getAttachmentRetriever() {
-		return attachmentController;
+		return attachmentRetriever;
 	}
 
 	LiveData<Contact> getContact() {

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

@@ -7,6 +7,7 @@ import android.support.annotation.UiThread;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.R;
+import org.briarproject.briar.android.attachment.AttachmentItem;
 import org.briarproject.briar.api.blog.BlogInvitationRequest;
 import org.briarproject.briar.api.blog.BlogInvitationResponse;
 import org.briarproject.briar.api.conversation.ConversationMessageVisitor;

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

@@ -31,6 +31,7 @@ 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.attachment.AttachmentItem;
 import org.briarproject.briar.android.util.BriarSnackbarBuilder;
 import org.briarproject.briar.android.view.PullDownLayout;
 

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

@@ -12,6 +12,7 @@ import android.view.WindowManager;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
+import org.briarproject.briar.android.attachment.AttachmentItem;
 import org.briarproject.briar.android.conversation.glide.Radii;
 
 import java.util.ArrayList;

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

@@ -21,6 +21,7 @@ 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.attachment.AttachmentItem;
 import org.briarproject.briar.android.conversation.glide.GlideApp;
 
 import javax.annotation.ParametersAreNonnullByDefault;

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

@@ -11,6 +11,7 @@ import com.bumptech.glide.load.Transformation;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
+import org.briarproject.briar.android.attachment.AttachmentItem;
 import org.briarproject.briar.android.conversation.glide.BriarImageTransformation;
 import org.briarproject.briar.android.conversation.glide.GlideApp;
 import org.briarproject.briar.android.conversation.glide.Radii;

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

@@ -13,6 +13,7 @@ import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.briar.android.attachment.AttachmentItem;
 import org.briarproject.briar.android.viewmodel.LiveEvent;
 import org.briarproject.briar.android.viewmodel.MutableLiveEvent;
 import org.briarproject.briar.api.messaging.Attachment;

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

@@ -10,7 +10,7 @@ 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.android.conversation.AttachmentItem;
+import org.briarproject.briar.android.attachment.AttachmentItem;
 import org.briarproject.briar.api.messaging.MessagingManager;
 
 import java.io.InputStream;

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

@@ -2,7 +2,7 @@ package org.briarproject.briar.android.conversation.glide;
 
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.briar.android.conversation.AttachmentItem;
+import org.briarproject.briar.android.attachment.AttachmentItem;
 import org.briarproject.briar.api.messaging.MessagingManager;
 
 import java.util.concurrent.Executor;

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

@@ -10,7 +10,7 @@ import com.bumptech.glide.module.AppGlideModule;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.android.BriarApplication;
-import org.briarproject.briar.android.conversation.AttachmentItem;
+import org.briarproject.briar.android.attachment.AttachmentItem;
 
 import java.io.InputStream;
 

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

@@ -8,7 +8,7 @@ import com.bumptech.glide.signature.ObjectKey;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.android.BriarApplication;
-import org.briarproject.briar.android.conversation.AttachmentItem;
+import org.briarproject.briar.android.attachment.AttachmentItem;
 
 import java.io.InputStream;
 

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

@@ -6,7 +6,7 @@ import com.bumptech.glide.load.model.MultiModelLoaderFactory;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.android.BriarApplication;
-import org.briarproject.briar.android.conversation.AttachmentItem;
+import org.briarproject.briar.android.attachment.AttachmentItem;
 
 import java.io.InputStream;
 

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

@@ -9,7 +9,7 @@ import android.view.LayoutInflater;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.conversation.AttachmentResult;
+import org.briarproject.briar.android.attachment.AttachmentItemResult;
 
 import java.util.Collection;
 
@@ -72,7 +72,7 @@ public class ImagePreview extends ConstraintLayout {
 		imageList.setAdapter(adapter);
 	}
 
-	void loadPreviewImage(AttachmentResult result) {
+	void loadPreviewImage(AttachmentItemResult result) {
 		ImagePreviewAdapter adapter =
 				((ImagePreviewAdapter) imageList.getAdapter());
 		requireNonNull(adapter).loadItemPreview(result);

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

@@ -8,7 +8,7 @@ import android.view.ViewGroup;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.conversation.AttachmentResult;
+import org.briarproject.briar.android.attachment.AttachmentItemResult;
 
 import java.util.ArrayList;
 import java.util.Collection;
@@ -50,7 +50,7 @@ class ImagePreviewAdapter extends Adapter<ImagePreviewViewHolder> {
 		return items.size();
 	}
 
-	void loadItemPreview(AttachmentResult result) {
+	void loadItemPreview(AttachmentItemResult result) {
 		ImagePreviewItem newItem =
 				new ImagePreviewItem(requireNonNull(result.getUri()));
 		int pos = items.indexOf(newItem);

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

@@ -4,7 +4,7 @@ import android.net.Uri;
 import android.support.annotation.Nullable;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.briar.android.conversation.AttachmentItem;
+import org.briarproject.briar.android.attachment.AttachmentItem;
 
 import java.util.ArrayList;
 import java.util.Collection;
@@ -30,10 +30,6 @@ class ImagePreviewItem {
 		return items;
 	}
 
-	Uri getUri() {
-		return uri;
-	}
-
 	public void setItem(AttachmentItem item) {
 		this.item = item;
 	}

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

@@ -38,9 +38,9 @@ class ImagePreviewViewHolder extends ViewHolder {
 	}
 
 	void bind(ImagePreviewItem item) {
-		if (item.getItem() == null) return;
+		if (item.getItem() == null) return;  // shows progress bar
 		GlideApp.with(imageView)
-				.load(item.getUri())
+				.load(item.getItem())
 				.diskCacheStrategy(NONE)
 				.error(ERROR_RES)
 				.downsample(FIT_CENTER)

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

@@ -3,6 +3,7 @@ package org.briarproject.briar.android.view;
 import android.app.Activity;
 import android.arch.lifecycle.LifecycleOwner;
 import android.arch.lifecycle.LiveData;
+import android.arch.lifecycle.Observer;
 import android.content.ClipData;
 import android.content.Context;
 import android.content.Intent;
@@ -17,9 +18,10 @@ import android.widget.Toast;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.conversation.AttachmentResult;
+import org.briarproject.briar.android.attachment.AttachmentItemResult;
+import org.briarproject.briar.android.attachment.AttachmentManager;
+import org.briarproject.briar.android.attachment.AttachmentResult;
 import org.briarproject.briar.android.view.ImagePreview.ImagePreviewListener;
-import org.briarproject.briar.api.messaging.AttachmentHeader;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -38,7 +40,6 @@ 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.widget.Toast.LENGTH_LONG;
-import static java.util.Collections.emptyList;
 import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.util.UiUtils.resolveColorAttribute;
 import static org.briarproject.briar.api.messaging.MessagingConstants.IMAGE_MIME_TYPES;
@@ -55,9 +56,8 @@ public class TextAttachmentController extends TextSendController
 	private final CompositeSendButton sendButton;
 	private final AttachmentManager attachmentManager;
 
-	private CharSequence textHint;
+	private final List<Uri> imageUris = new ArrayList<>();
-	private List<Uri> imageUris = emptyList();
+	private final CharSequence textHint;
-	private int urisLoaded = 0;
 	private boolean loadingUris = false;
 
 	public TextAttachmentController(TextInputView v, ImagePreview imagePreview,
@@ -96,7 +96,7 @@ public class TextAttachmentController extends TextSendController
 		if (canSend()) {
 			if (loadingUris) throw new AssertionError();
 			listener.onSendClick(textInput.getText(),
-					attachmentManager.getAttachmentHeaders());
+					attachmentManager.getAttachmentHeadersForSending());
 			reset();
 		}
 	}
@@ -140,14 +140,12 @@ public class TextAttachmentController extends TextSendController
 
 	public void onImageReceived(@Nullable Intent resultData) {
 		if (resultData == null) return;
-		if (loadingUris) throw new AssertionError();
+		if (loadingUris || !imageUris.isEmpty()) throw new AssertionError();
 		if (resultData.getData() != null) {
-			imageUris = new ArrayList<>(1);
 			imageUris.add(resultData.getData());
 			onNewUris();
 		} else if (SDK_INT >= 18 && resultData.getClipData() != null) {
 			ClipData clipData = resultData.getClipData();
-			imageUris = new ArrayList<>(clipData.getItemCount());
 			for (int i = 0; i < clipData.getItemCount(); i++) {
 				imageUris.add(clipData.getItemAt(i).getUri());
 			}
@@ -157,40 +155,62 @@ public class TextAttachmentController extends TextSendController
 
 	private void onNewUris() {
 		if (imageUris.isEmpty()) return;
-		if (loadingUris || urisLoaded != 0) throw new AssertionError();
+		if (loadingUris) throw new AssertionError();
 		loadingUris = true;
 		updateViewState();
 		textInput.setHint(R.string.image_caption_hint);
 		List<ImagePreviewItem> items = ImagePreviewItem.fromUris(imageUris);
 		imagePreview.showPreview(items);
 		// store attachments and show preview when successful
-		boolean needsSize = items.size() == 1;
+		AttachmentResult result = attachmentManager.storeAttachments(imageUris);
-		for (ImagePreviewItem item : items) {
+		for (LiveData<AttachmentItemResult> liveData : result
-			attachmentManager.storeAttachment(item.getUri(), needsSize)
+				.getItemResults()) {
-					.observe(imageListener, this::onAttachmentResultReceived);
+			onLiveDataReturned(liveData);
 		}
+		result.getFinished().observe(imageListener, new Observer<Boolean>() {
+			@Override
+			public void onChanged(@Nullable Boolean finished) {
+				if (finished != null && finished) onAllAttachmentsCreated();
+				result.getFinished().removeObserver(this);
+			}
+		});
 	}
 
-	private void onAttachmentResultReceived(AttachmentResult result) {
+	private void onLiveDataReturned(LiveData<AttachmentItemResult> liveData) {
-		if (!loadingUris) return;  // if this is false, the user cancelled
+		liveData.observe(imageListener, new Observer<AttachmentItemResult>() {
+			@Override
+			public void onChanged(@Nullable AttachmentItemResult result) {
+				if (result != null) {
+					onAttachmentResultReceived(result);
+				}
+				liveData.removeObserver(this);
+			}
+		});
+	}
+
+	private void onAttachmentResultReceived(AttachmentItemResult result) {
+		if (!loadingUris) throw new AssertionError();
 		if (result.isError() || result.getUri() == null) {
 			onError(result.getErrorMsg());
 		} else {
 			imagePreview.loadPreviewImage(result);
-			urisLoaded++;
-			checkAllUrisLoaded();
 		}
 	}
 
+	private void onAllAttachmentsCreated() {
+		if (!loadingUris) throw new AssertionError();
+		loadingUris = false;
+		updateViewState();
+	}
+
 	private void reset() {
 		// restore hint
 		textInput.setHint(textHint);
 		// hide image layout
 		imagePreview.setVisibility(GONE);
 		// reset image URIs
-		imageUris = emptyList();
+		imageUris.clear();
-		// no URIs has been loaded
+		// definitely not loading anymore
-		urisLoaded = 0;
 		loadingUris = false;
 		// show the image button again, so images can get attached
 		updateViewState();
@@ -208,7 +228,8 @@ public class TextAttachmentController extends TextSendController
 	@Nullable
 	public Parcelable onRestoreInstanceState(Parcelable inState) {
 		SavedState state = (SavedState) inState;
-		imageUris = requireNonNull(state.imageUris);
+		if (!imageUris.isEmpty()) throw new AssertionError();
+		if (state.imageUris != null) imageUris.addAll(state.imageUris);
 		onNewUris();
 		return state.getSuperState();
 	}
@@ -226,19 +247,10 @@ public class TextAttachmentController extends TextSendController
 	@Override
 	public void onCancel() {
 		textInput.clearText();
-		attachmentManager.removeAttachments();
+		attachmentManager.cancel();
 		reset();
 	}
 
-	private void checkAllUrisLoaded() {
-		if (!loadingUris) throw new AssertionError();
-		if (urisLoaded == imageUris.size()) {
-			loadingUris = false;
-			// all images were turned into attachments
-			updateViewState();
-		}
-	}
-
 	public void showImageOnboarding(Activity activity,
 			Runnable onOnboardingSeen) {
 		PromptStateChangeListener listener = (prompt, state) -> {
@@ -297,19 +309,4 @@ public class TextAttachmentController extends TextSendController
 		void onAttachImage(Intent intent);
 	}
 
-	public interface AttachmentManager {
-		/**
-		 * Stores a new attachment in the database.
-		 *
-		 * @param uri The Uri of the attachment to store.
-		 * @param needsSize true if this is the only image in the message
-		 * and therefore needs to know its size.
-		 */
-		LiveData<AttachmentResult> storeAttachment(Uri uri, boolean needsSize);
-
-		List<AttachmentHeader> getAttachmentHeaders();
-
-		void removeAttachments();
-	}
-
 }

briar-android/src/test/java/org/briarproject/briar/android/attachment/AttachmentRetrieverTest.java

@@ -1,8 +1,8 @@
-package org.briarproject.briar.android.conversation;
+package org.briarproject.briar.android.attachment;
 
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.test.BrambleMockTestCase;
-import org.briarproject.briar.android.conversation.ImageHelper.DecodeResult;
+import org.briarproject.briar.android.attachment.ImageHelper.DecodeResult;
 import org.briarproject.briar.api.messaging.Attachment;
 import org.briarproject.briar.api.messaging.AttachmentHeader;
 import org.briarproject.briar.api.messaging.MessagingManager;
@@ -19,7 +19,7 @@ import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
-public class AttachmentControllerTest extends BrambleMockTestCase {
+public class AttachmentRetrieverTest extends BrambleMockTestCase {
 
 	private final AttachmentDimensions dimensions = new AttachmentDimensions(
 			100, 50, 200, 75, 300
@@ -32,8 +32,8 @@ public class AttachmentControllerTest extends BrambleMockTestCase {
 	private final MessagingManager messagingManager =
 			context.mock(MessagingManager.class);
 	private final ImageHelper imageHelper = context.mock(ImageHelper.class);
-	private final AttachmentController controller =
+	private final AttachmentRetriever controller =
-			new AttachmentController(
+			new AttachmentRetriever(
 					messagingManager,
 					dimensions,
 					imageHelper

briar-android/src/test/java/org/briarproject/briar/android/attachment/MarkEnforcingInputStreamTest.java

@@ -1,4 +1,4 @@
-package org.briarproject.briar.android.conversation;
+package org.briarproject.briar.android.attachment;
 
 import com.bumptech.glide.util.MarkEnforcingInputStream;
 

briar-core/src/main/java/org/briarproject/briar/messaging/MessagingManagerImpl.java

@@ -174,6 +174,10 @@ class MessagingManagerImpl extends ConversationClientImpl
 		}
 		if (is.available() > 0) throw new FileTooBigException();
 		is.close();
+		try {
+			Thread.sleep(1000);
+		} catch (InterruptedException ignored) {
+		}
 		Message m = messageFactory.createMessage(groupId, timestamp, body);
 		clientHelper.addLocalMessage(m, new BdfDictionary(), false);
 		return new AttachmentHeader(m.getId(), contentType);