[android] Add support for saving image attachments on API < 19

This is done by using the WRITE_EXTERNAL_STORAGE permission
to write the file directly without using the system activity.

briar-android/src/main/AndroidManifest.xml

@@ -17,6 +17,7 @@
 	<uses-permission android:name="android.permission.USE_FINGERPRINT"/>
 	<uses-permission android:name="android.permission.VIBRATE" />
 	<uses-permission android:name="android.permission.WAKE_LOCK" />
+	<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
 	<uses-permission-sdk-23 android:name="android.permission.ACCESS_COARSE_LOCATION" />
 	<uses-permission-sdk-23 android:name="android.permission.REQUEST_IGNORE_BATTERY_OPTIMIZATIONS"/>
 	<uses-permission-sdk-23 android:name="android.permission.USE_BIOMETRIC" />

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

@@ -1,10 +1,11 @@
 package org.briarproject.briar.android.conversation;
 
+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.net.Uri;
 import android.os.Bundle;
 import android.support.annotation.Nullable;
 import android.support.annotation.RequiresApi;
@@ -26,25 +27,15 @@ import com.bumptech.glide.request.RequestListener;
 import com.bumptech.glide.request.target.Target;
 import com.github.chrisbanes.photoview.PhotoView;
 
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.lifecycle.IoExecutor;
-import org.briarproject.bramble.api.sync.MessageId;
 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 org.briarproject.briar.api.messaging.Attachment;
-import org.briarproject.briar.api.messaging.MessagingManager;
 
-import java.io.IOException;
-import java.io.InputStream;
-import java.io.OutputStream;
 import java.text.SimpleDateFormat;
 import java.util.Date;
 import java.util.Locale;
-import java.util.concurrent.Executor;
-import java.util.logging.Logger;
 
 import javax.inject.Inject;
 
@@ -63,28 +54,20 @@ 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 java.util.logging.Level.WARNING;
-import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.util.IoUtils.copyAndClose;
-import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_SAVE_ATTACHMENT;
 import static org.briarproject.briar.android.util.UiUtils.formatDateAbsolute;
 
 public class ImageActivity extends BriarActivity
 		implements PullDownLayout.Callback {
 
-	private final static Logger LOG = getLogger(ImageActivity.class.getName());
-
 	final static String ATTACHMENT = "attachment";
 	final static String NAME = "name";
 	final static String DATE = "date";
 
 	@Inject
-	MessagingManager messagingManager;
-	@Inject
-	@IoExecutor
-	Executor ioExecutor;
+	ViewModelProvider.Factory viewModelFactory;
 
+	private ImageViewModel viewModel;
 	private PullDownLayout layout;
 	private AppBarLayout appBarLayout;
 	private PhotoView photoView;
@@ -107,6 +90,11 @@ public class ImageActivity extends BriarActivity
 			setSceneTransitionAnimation(transition, null, transition);
 		}
 
+		// get View Model
+		viewModel = ViewModelProviders.of(this, viewModelFactory)
+				.get(ImageViewModel.class);
+		viewModel.getSaveState().observe(this, this::onImageSaveStateChanged);
+
 		// inflate layout
 		setContentView(R.layout.activity_image);
 		layout = findViewById(R.id.layout);
@@ -186,9 +174,6 @@ public class ImageActivity extends BriarActivity
 	@Override
 	public boolean onCreateOptionsMenu(Menu menu) {
 		getMenuInflater().inflate(R.menu.image_actions, menu);
-		if (SDK_INT >= 19) {
-			menu.findItem(R.id.action_save_image).setVisible(true);
-		}
 		return super.onCreateOptionsMenu(menu);
 	}
 
@@ -199,7 +184,7 @@ public class ImageActivity extends BriarActivity
 				onBackPressed();
 				return true;
 			case R.id.action_save_image:
-				if (SDK_INT >= 19) startSaveImage();
+				showSaveImageDialog();
 				return true;
 			default:
 				return super.onOptionsItemSelected(item);
@@ -210,7 +195,7 @@ public class ImageActivity extends BriarActivity
 	protected void onActivityResult(int request, int result, Intent data) {
 		super.onActivityResult(request, result, data);
 		if (request == REQUEST_SAVE_ATTACHMENT && result == RESULT_OK) {
-			saveImage(data.getData());
+			viewModel.saveImage(attachment, data.getData());
 		}
 	}
 
@@ -250,9 +235,8 @@ public class ImageActivity extends BriarActivity
 
 	@RequiresApi(api = 16)
 	private void hideSystemUi(View decorView) {
-		decorView.setSystemUiVisibility(SYSTEM_UI_FLAG_LAYOUT_STABLE
-				| SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
-				| SYSTEM_UI_FLAG_FULLSCREEN
+		decorView.setSystemUiVisibility(SYSTEM_UI_FLAG_FULLSCREEN |
+				SYSTEM_UI_FLAG_LAYOUT_STABLE | SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
 		);
 		appBarLayout.animate()
 				.translationYBy(-1 * appBarLayout.getHeight())
@@ -264,8 +248,7 @@ public class ImageActivity extends BriarActivity
 	@RequiresApi(api = 16)
 	private void showSystemUi(View decorView) {
 		decorView.setSystemUiVisibility(
-				SYSTEM_UI_FLAG_LAYOUT_STABLE
-						| SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
+				SYSTEM_UI_FLAG_LAYOUT_STABLE | SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
 		);
 		appBarLayout.animate()
 				.translationYBy(appBarLayout.getHeight())
@@ -290,11 +273,14 @@ public class ImageActivity extends BriarActivity
 				drawableTop != appBarLayout.getTop();
 	}
 
-	@RequiresApi(api = 19)
-	private void startSaveImage() {
+	private void showSaveImageDialog() {
 		OnClickListener okListener = (dialog, which) -> {
-			Intent intent = getCreationIntent();
-			startActivityForResult(intent, REQUEST_SAVE_ATTACHMENT);
+			if (SDK_INT >= 19) {
+				Intent intent = getCreationIntent();
+				startActivityForResult(intent, REQUEST_SAVE_ATTACHMENT);
+			} else {
+				viewModel.saveImage(attachment);
+			}
 		};
 		Builder builder = new Builder(this, R.style.BriarDialogTheme);
 		builder.setTitle(getString(R.string.dialog_title_save_image));
@@ -317,39 +303,16 @@ public class ImageActivity extends BriarActivity
 		return intent;
 	}
 
-	private void saveImage(@Nullable Uri uri) {
-		if (uri == null) return;
-		MessageId messageId = attachment.getMessageId();
-		runOnDbThread(() -> {
-			try {
-				Attachment a = messagingManager.getAttachment(messageId);
-				copyImageFromDb(a, uri);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				onImageSaveError();
-			}
-		});
-	}
-
-	private void copyImageFromDb(Attachment a, Uri uri) {
-		ioExecutor.execute(() -> {
-			try {
-				InputStream is = a.getStream();
-				OutputStream os = getContentResolver().openOutputStream(uri);
-				if (os == null) throw new IOException();
-				copyAndClose(is, os);
-			} catch (IOException e) {
-				logException(LOG, WARNING, e);
-				onImageSaveError();
-			}
-		});
-	}
-
-	private void onImageSaveError() {
-		Snackbar s =
-				Snackbar.make(layout, R.string.save_image_error, LENGTH_LONG);
-		s.getView().setBackgroundResource(R.color.briar_red);
+	private void onImageSaveStateChanged(@Nullable Boolean error) {
+		if (error == null) return;
+		int stringRes = error ?
+				R.string.save_image_error : R.string.save_image_success;
+		int colorRes = error ?
+				R.color.briar_red : R.color.briar_primary;
+		Snackbar s = Snackbar.make(layout, stringRes, LENGTH_LONG);
+		s.getView().setBackgroundResource(colorRes);
 		s.show();
+		viewModel.onSaveStateSeen();
 	}
 
 }

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

@@ -0,0 +1,168 @@
+package org.briarproject.briar.android.conversation;
+
+import android.app.Application;
+import android.arch.lifecycle.AndroidViewModel;
+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.DatabaseExecutor;
+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.api.messaging.Attachment;
+import org.briarproject.briar.api.messaging.MessagingManager;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.text.SimpleDateFormat;
+import java.util.Date;
+import java.util.Locale;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.inject.Inject;
+
+import static android.media.MediaScannerConnection.scanFile;
+import static android.os.Environment.DIRECTORY_PICTURES;
+import static android.os.Environment.getExternalStoragePublicDirectory;
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.IoUtils.copyAndClose;
+import static org.briarproject.bramble.util.LogUtils.logException;
+
+@NotNullByDefault
+public class ImageViewModel extends AndroidViewModel {
+
+	private static Logger LOG = getLogger(ImageViewModel.class.getName());
+
+	private final MessagingManager messagingManager;
+	@DatabaseExecutor
+	private final Executor dbExecutor;
+	@IoExecutor
+	private final Executor ioExecutor;
+
+	private MutableLiveData<Boolean> saveState = new MutableLiveData<>();
+
+	@Inject
+	public ImageViewModel(Application application,
+			MessagingManager messagingManager,
+			@DatabaseExecutor Executor dbExecutor,
+			@IoExecutor Executor ioExecutor) {
+		super(application);
+		this.messagingManager = messagingManager;
+		this.dbExecutor = dbExecutor;
+		this.ioExecutor = ioExecutor;
+	}
+
+	/**
+	 * A LiveData that is true if the image was saved,
+	 * false if there was an error and null otherwise.
+	 *
+	 * Call {@link #onSaveStateSeen()} after consuming an update.
+	 */
+	LiveData<Boolean> getSaveState() {
+		return saveState;
+	}
+
+	@UiThread
+	void onSaveStateSeen() {
+		saveState.setValue(null);
+	}
+
+	/**
+	 * Saves the attachment to a writeable {@link Uri}.
+	 */
+	@UiThread
+	void saveImage(AttachmentItem attachment, @Nullable Uri uri) {
+		if (uri == null) {
+			saveState.setValue(true);
+		} else {
+			saveImage(attachment, () -> getOutputStream(uri), null);
+		}
+	}
+
+	/**
+	 * Saves the attachment on external storage,
+	 * assuming the permission was granted during install time.
+	 */
+	void saveImage(AttachmentItem attachment) {
+		File file = getImageFile(attachment);
+		saveImage(attachment, () -> getOutputStream(file), () -> {
+			scanFile(getApplication(), new String[] {file.toString()}, null,
+					null);
+		});
+	}
+
+	private void saveImage(AttachmentItem attachment, OutputStreamProvider osp,
+			@Nullable Runnable afterCopy) {
+		MessageId messageId = attachment.getMessageId();
+		dbExecutor.execute(() -> {
+			try {
+				Attachment a = messagingManager.getAttachment(messageId);
+				copyImageFromDb(a, osp, afterCopy);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+				saveState.postValue(true);
+			}
+		});
+	}
+
+	private void copyImageFromDb(Attachment a, OutputStreamProvider osp,
+			@Nullable Runnable afterCopy) {
+		ioExecutor.execute(() -> {
+			try {
+				InputStream is = a.getStream();
+				OutputStream os = osp.getOutputStream();
+				copyAndClose(is, os);
+				if (afterCopy != null) afterCopy.run();
+				saveState.postValue(false);
+			} catch (IOException e) {
+				logException(LOG, WARNING, e);
+				saveState.postValue(true);
+			}
+		});
+	}
+
+	private String getFileName() {
+		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss",
+				Locale.getDefault());
+		return sdf.format(new Date());
+	}
+
+	private File getImageFile(AttachmentItem attachment) {
+		File path = getExternalStoragePublicDirectory(DIRECTORY_PICTURES);
+		//noinspection ResultOfMethodCallIgnored
+		path.mkdirs();
+		String fileName = getFileName();
+		String ext = attachment.getMimeType().replaceFirst("image/", ".");
+		File file = new File(path, fileName + ext);
+		int i = 1;
+		while (file.exists()) {
+			file = new File(path, fileName + " (" + i + ")" + ext);
+		}
+		return file;
+	}
+
+	private OutputStream getOutputStream(File file) throws IOException {
+		return new FileOutputStream(file);
+	}
+
+	private OutputStream getOutputStream(Uri uri) throws IOException {
+		OutputStream os =
+				getApplication().getContentResolver().openOutputStream(uri);
+		if (os == null) throw new IOException();
+		return os;
+	}
+
+	private interface OutputStreamProvider {
+		OutputStream getOutputStream() throws IOException;
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/viewmodel/ViewModelModule.java

@@ -4,6 +4,7 @@ import android.arch.lifecycle.ViewModel;
 import android.arch.lifecycle.ViewModelProvider;
 
 import org.briarproject.briar.android.conversation.ConversationViewModel;
+import org.briarproject.briar.android.conversation.ImageViewModel;
 
 import javax.inject.Singleton;
 
@@ -20,6 +21,12 @@ public abstract class ViewModelModule {
 	abstract ViewModel bindConversationViewModel(
 			ConversationViewModel conversationViewModel);
 
+	@Binds
+	@IntoMap
+	@ViewModelKey(ImageViewModel.class)
+	abstract ViewModel bindImageViewModel(
+			ImageViewModel imageViewModel);
+
 	@Binds
 	@Singleton
 	abstract ViewModelProvider.Factory bindViewModelFactory(

briar-android/src/main/res/menu/image_actions.xml

@@ -6,6 +6,5 @@
 	<item
 		android:id="@+id/action_save_image"
 		android:title="@string/save_image"
-		android:visible="false"
 		app:showAsAction="never"/>
 </menu>

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

@@ -142,6 +142,7 @@
 	<string name="save_image">Save image</string>
 	<string name="dialog_title_save_image">Save Image?</string>
 	<string name="dialog_message_save_image">Saving this image will allow other apps to access it.\n\nAre you sure you want to save?</string>
+	<string name="save_image_success">Image was saved</string>
 	<string name="save_image_error">Could not save image</string>
 
 	<!-- Adding Contacts -->