fullscreen: stream image in chunks instead of reading and sending all at once

android/app/build.gradle

@@ -62,4 +62,6 @@ dependencies {
     testImplementation 'junit:junit:4.13'
     androidTestImplementation 'androidx.test:runner:1.2.0'
     androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
+
+    compileOnly rootProject.findProject(':streams_channel')
 }

android/app/src/main/java/deckers/thibault/aves/MainActivity.java

@@ -8,9 +8,11 @@ import android.util.Log;
 import java.util.HashMap;
 import java.util.Map;
 
+import app.loup.streams_channel.StreamsChannel;
 import deckers.thibault.aves.channelhandlers.AppAdapterHandler;
 import deckers.thibault.aves.channelhandlers.FileAdapterHandler;
 import deckers.thibault.aves.channelhandlers.ImageFileHandler;
+import deckers.thibault.aves.channelhandlers.ImageStreamHandler;
 import deckers.thibault.aves.channelhandlers.MediaStoreStreamHandler;
 import deckers.thibault.aves.channelhandlers.MetadataHandler;
 import deckers.thibault.aves.utils.Constants;
@@ -46,6 +48,9 @@ public class MainActivity extends FlutterActivity {
         new MethodChannel(messenger, MetadataHandler.CHANNEL).setMethodCallHandler(new MetadataHandler(this));
         new EventChannel(messenger, MediaStoreStreamHandler.CHANNEL).setStreamHandler(mediaStoreStreamHandler);
 
+        final StreamsChannel imageStreamChannel = new StreamsChannel(messenger, ImageStreamHandler.CHANNEL);
+        imageStreamChannel.setStreamHandlerFactory(arguments -> new ImageStreamHandler(this, arguments));
+
         new MethodChannel(messenger, VIEWER_CHANNEL).setMethodCallHandler(
                 (call, result) -> {
                     if (call.method.contentEquals("getSharedEntry")) {

android/app/src/main/java/deckers/thibault/aves/channelhandlers/ImageFileHandler.java

@@ -1,32 +1,17 @@
 package deckers.thibault.aves.channelhandlers;
 
 import android.app.Activity;
-import android.content.ContentResolver;
-import android.graphics.Bitmap;
-import android.graphics.ImageDecoder;
 import android.net.Uri;
-import android.os.Build;
 import android.os.Handler;
 import android.os.Looper;
 
 import androidx.annotation.NonNull;
 
-import com.bumptech.glide.Glide;
-import com.bumptech.glide.load.engine.DiskCacheStrategy;
-import com.bumptech.glide.request.FutureTarget;
-import com.bumptech.glide.request.RequestOptions;
-import com.bumptech.glide.request.target.Target;
-
-import java.io.ByteArrayOutputStream;
-import java.io.IOException;
-import java.io.InputStream;
 import java.util.Map;
 
-import deckers.thibault.aves.decoder.VideoThumbnail;
 import deckers.thibault.aves.model.ImageEntry;
 import deckers.thibault.aves.model.provider.ImageProvider;
 import deckers.thibault.aves.model.provider.ImageProviderFactory;
-import deckers.thibault.aves.utils.MimeTypes;
 import io.flutter.plugin.common.MethodCall;
 import io.flutter.plugin.common.MethodChannel;
 
@@ -51,9 +36,6 @@ public class ImageFileHandler implements MethodChannel.MethodCallHandler {
             case "getImageEntry":
                 new Thread(() -> getImageEntry(call, new MethodResultWrapper(result))).start();
                 break;
-            case "getImage":
-                new Thread(() -> getImage(call, new MethodResultWrapper(result))).start();
-                break;
             case "getThumbnail":
                 new Thread(() -> getThumbnail(call, new MethodResultWrapper(result))).start();
                 break;
@@ -72,71 +54,6 @@ public class ImageFileHandler implements MethodChannel.MethodCallHandler {
         }
     }
 
-    private void getImage(@NonNull MethodCall call, @NonNull MethodChannel.Result result) {
-        String mimeType = call.argument("mimeType");
-        String uriString = call.argument("uri");
-
-        Uri uri = Uri.parse(uriString);
-
-        byte[] data = null;
-        if (mimeType != null && mimeType.startsWith(MimeTypes.VIDEO)) {
-            RequestOptions options = new RequestOptions()
-                    .diskCacheStrategy(DiskCacheStrategy.RESOURCE);
-            FutureTarget<Bitmap> target = Glide.with(activity)
-                    .asBitmap()
-                    .apply(options)
-                    .load(new VideoThumbnail(activity, uri))
-                    .submit(Target.SIZE_ORIGINAL, Target.SIZE_ORIGINAL);
-            try {
-                Bitmap bitmap = target.get();
-                if (bitmap != null) {
-                    ByteArrayOutputStream stream = new ByteArrayOutputStream();
-                    // we compress the bitmap because Dart Image.memory cannot decode the raw bytes
-                    // Bitmap.CompressFormat.PNG is slower than JPEG
-                    bitmap.compress(Bitmap.CompressFormat.JPEG, 90, stream);
-                    data = stream.toByteArray();
-                }
-            } catch (Exception e) {
-                result.error("getImage-video-exception", "failed to get image from uri=" + uri, e.getMessage());
-                return;
-            }
-            Glide.with(activity).clear(target);
-        } else {
-            ContentResolver cr = activity.getContentResolver();
-            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P && (MimeTypes.HEIC.equals(mimeType) || MimeTypes.HEIF.equals(mimeType))) {
-                // as of Flutter v1.15.17, Dart Image.memory cannot decode HEIF/HEIC images
-                // so we convert the image using Android native decoder
-                try {
-                    ImageDecoder.Source source = ImageDecoder.createSource(cr, uri);
-                    Bitmap bitmap = ImageDecoder.decodeBitmap(source);
-                    ByteArrayOutputStream stream = new ByteArrayOutputStream();
-                    // we compress the bitmap because Dart Image.memory cannot decode the raw bytes
-                    // Bitmap.CompressFormat.PNG is slower than JPEG
-                    bitmap.compress(Bitmap.CompressFormat.JPEG, 90, stream);
-                    data = stream.toByteArray();
-                } catch (IOException e) {
-                    result.error("getImage-decode-exception", "failed to decode image from uri=" + uri, e.getMessage());
-                    return;
-                }
-            } else {
-                try (InputStream is = cr.openInputStream(uri)) {
-                    if (is != null) {
-                        data = getBytes(is);
-                    }
-                } catch (IOException e) {
-                    result.error("getImage-read-exception", "failed to get image from uri=" + uri, e.getMessage());
-                    return;
-                }
-            }
-        }
-
-        if (data != null) {
-            result.success(data);
-        } else {
-            result.error("getImage-null", "failed to get image from uri=" + uri, null);
-        }
-    }
-
     private void getThumbnail(@NonNull MethodCall call, @NonNull MethodChannel.Result result) {
         Map entryMap = call.argument("entry");
         Integer width = call.argument("width");
@@ -261,19 +178,4 @@ public class ImageFileHandler implements MethodChannel.MethodCallHandler {
             }
         });
     }
-
-    // convenience methods
-
-    // InputStream.readAllBytes is only available from Java 9+
-    private byte[] getBytes(InputStream inputStream) throws IOException {
-        ByteArrayOutputStream byteBuffer = new ByteArrayOutputStream();
-        int bufferSize = 1024;
-        byte[] buffer = new byte[bufferSize];
-
-        int len;
-        while ((len = inputStream.read(buffer)) != -1) {
-            byteBuffer.write(buffer, 0, len);
-        }
-        return byteBuffer.toByteArray();
-    }
 }

android/app/src/main/java/deckers/thibault/aves/channelhandlers/ImageStreamHandler.java

@@ -0,0 +1,135 @@
+package deckers.thibault.aves.channelhandlers;
+
+import android.app.Activity;
+import android.content.ContentResolver;
+import android.graphics.Bitmap;
+import android.graphics.ImageDecoder;
+import android.net.Uri;
+import android.os.Build;
+import android.os.Handler;
+import android.os.Looper;
+
+import com.bumptech.glide.Glide;
+import com.bumptech.glide.load.engine.DiskCacheStrategy;
+import com.bumptech.glide.request.FutureTarget;
+import com.bumptech.glide.request.RequestOptions;
+import com.bumptech.glide.request.target.Target;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.Map;
+
+import deckers.thibault.aves.decoder.VideoThumbnail;
+import deckers.thibault.aves.utils.MimeTypes;
+import io.flutter.plugin.common.EventChannel;
+
+public class ImageStreamHandler implements EventChannel.StreamHandler {
+    public static final String CHANNEL = "deckers.thibault/aves/imagestream";
+
+    private Activity activity;
+    private Uri uri;
+    private String mimeType;
+    private EventChannel.EventSink eventSink;
+    private Handler handler;
+
+    public ImageStreamHandler(Activity activity, Object arguments) {
+        this.activity = activity;
+        if (arguments instanceof Map) {
+            Map argMap = (Map) arguments;
+            this.mimeType = (String) argMap.get("mimeType");
+            this.uri = Uri.parse((String) argMap.get("uri"));
+        }
+    }
+
+    @Override
+    public void onListen(Object o, final EventChannel.EventSink eventSink) {
+        this.eventSink = eventSink;
+        this.handler = new Handler(Looper.getMainLooper());
+        new Thread(this::getImage).start();
+    }
+
+    @Override
+    public void onCancel(Object o) {
+    }
+
+    private void success(final byte[] bytes) {
+        handler.post(() -> eventSink.success(bytes));
+    }
+
+    private void error(final String errorCode, final String errorMessage, final Object errorDetails) {
+        handler.post(() -> eventSink.error(errorCode, errorMessage, errorDetails));
+    }
+
+    private void endOfStream() {
+        handler.post(() -> eventSink.endOfStream());
+    }
+
+    private void getImage() {
+        if (mimeType != null && mimeType.startsWith(MimeTypes.VIDEO)) {
+            RequestOptions options = new RequestOptions()
+                    .diskCacheStrategy(DiskCacheStrategy.RESOURCE);
+            FutureTarget<Bitmap> target = Glide.with(activity)
+                    .asBitmap()
+                    .apply(options)
+                    .load(new VideoThumbnail(activity, uri))
+                    .submit(Target.SIZE_ORIGINAL, Target.SIZE_ORIGINAL);
+            try {
+                Bitmap bitmap = target.get();
+                if (bitmap != null) {
+                    ByteArrayOutputStream stream = new ByteArrayOutputStream();
+                    // we compress the bitmap because Dart Image.memory cannot decode the raw bytes
+                    // Bitmap.CompressFormat.PNG is slower than JPEG
+                    bitmap.compress(Bitmap.CompressFormat.JPEG, 90, stream);
+                    success(stream.toByteArray());
+                } else {
+                    error("getImage-video-null", "failed to get image from uri=" + uri, null);
+                }
+            } catch (Exception e) {
+                error("getImage-video-exception", "failed to get image from uri=" + uri, e.getMessage());
+                return;
+            }
+            Glide.with(activity).clear(target);
+        } else {
+            ContentResolver cr = activity.getContentResolver();
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P && (MimeTypes.HEIC.equals(mimeType) || MimeTypes.HEIF.equals(mimeType))) {
+                // as of Flutter v1.15.17, Dart Image.memory cannot decode HEIF/HEIC images
+                // so we convert the image using Android native decoder
+                try {
+                    ImageDecoder.Source source = ImageDecoder.createSource(cr, uri);
+                    Bitmap bitmap = ImageDecoder.decodeBitmap(source);
+                    ByteArrayOutputStream stream = new ByteArrayOutputStream();
+                    // we compress the bitmap because Dart Image.memory cannot decode the raw bytes
+                    // Bitmap.CompressFormat.PNG is slower than JPEG
+                    bitmap.compress(Bitmap.CompressFormat.JPEG, 90, stream);
+                    success(stream.toByteArray());
+                } catch (IOException e) {
+                    error("getImage-image-decode-exception", "failed to decode image from uri=" + uri, e.getMessage());
+                }
+            } else {
+                try (InputStream is = cr.openInputStream(uri)) {
+                    if (is != null) {
+                        streamBytes(is);
+                    } else {
+                        error("getImage-image-read-null", "failed to get image from uri=" + uri, null);
+                    }
+                } catch (IOException e) {
+                    error("getImage-image-read-exception", "failed to get image from uri=" + uri, e.getMessage());
+                }
+            }
+        }
+        endOfStream();
+    }
+
+    private void streamBytes(InputStream inputStream) throws IOException {
+        int bufferSize = 2 << 17; // ~250k
+        byte[] buffer = new byte[bufferSize];
+        int len;
+        while ((len = inputStream.read(buffer)) != -1) {
+            // cannot decode image on Flutter side when using `buffer` directly...
+            byte[] sub = new byte[len];
+            System.arraycopy(buffer, 0, sub, 0, len);
+            success(sub);
+        }
+    }
+}

lib/services/image_file_service.dart

@@ -1,12 +1,16 @@
+import 'dart:async';
+import 'dart:io';
 import 'dart:typed_data';
 
 import 'package:aves/model/image_entry.dart';
 import 'package:aves/services/service_policy.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart';
+import 'package:streams_channel/streams_channel.dart';
 
 class ImageFileService {
   static const platform = MethodChannel('deckers.thibault/aves/image');
+  static final StreamsChannel streamsChannel = StreamsChannel('deckers.thibault/aves/imagestream');
 
   static Future<void> getImageEntries() async {
     try {
@@ -30,24 +34,30 @@ class ImageFileService {
     return null;
   }
 
-  static Future<Uint8List> getImage(String uri, String mimeType) async {
+  static Future<Uint8List> getImage(String uri, String mimeType) {
     try {
-      final result = await platform.invokeMethod('getImage', <String, dynamic>{
+      final completer = Completer<Uint8List>();
+      final bytesBuilder = BytesBuilder(copy: false);
+      streamsChannel.receiveBroadcastStream(<String, dynamic>{
         'uri': uri,
         'mimeType': mimeType,
-      });
+      }).listen(
-      return result as Uint8List;
+        (data) => bytesBuilder.add(data as Uint8List),
+        onError: completer.completeError,
+        onDone: () => completer.complete(bytesBuilder.takeBytes()),
+        cancelOnError: true,
+      );
+      return completer.future;
     } on PlatformException catch (e) {
       debugPrint('getImage failed with code=${e.code}, exception=${e.message}, details=${e.details}');
     }
-    return Uint8List(0);
+    return Future.sync(() => Uint8List(0));
   }
 
   static Future<Uint8List> getThumbnail(ImageEntry entry, int width, int height, {Object cancellationKey}) {
     return servicePolicy.call(
       () async {
         if (width > 0 && height > 0) {
-//      debugPrint('getThumbnail width=$width path=${entry.path}');
           try {
             final result = await platform.invokeMethod('getThumbnail', <String, dynamic>{
               'entry': entry.toMap(),

lib/widgets/album/empty.dart

@@ -4,17 +4,19 @@ import 'package:outline_material_icons/outline_material_icons.dart';
 class EmptyContent extends StatelessWidget {
   final IconData icon;
   final String text;
+  final AlignmentGeometry alignment;
 
   const EmptyContent({
     this.icon = OMIcons.photo,
     this.text = 'Nothing!',
+    this.alignment = const FractionalOffset(.5, .35),
   });
 
   @override
   Widget build(BuildContext context) {
     const color = Color(0xFF607D8B);
     return Align(
-      alignment: const FractionalOffset(.5, .35),
+      alignment: alignment,
       child: Column(
         mainAxisSize: MainAxisSize.min,
         children: [

lib/widgets/fullscreen/image_view.dart

@@ -1,12 +1,14 @@
 import 'package:aves/model/image_entry.dart';
 import 'package:aves/utils/constants.dart';
+import 'package:aves/widgets/album/empty.dart';
 import 'package:aves/widgets/common/image_providers/thumbnail_provider.dart';
 import 'package:aves/widgets/common/image_providers/uri_image_provider.dart';
 import 'package:aves/widgets/common/image_providers/uri_picture_provider.dart';
 import 'package:aves/widgets/fullscreen/video_view.dart';
-import 'package:flutter_ijkplayer/flutter_ijkplayer.dart';
 import 'package:flutter/material.dart';
+import 'package:flutter_ijkplayer/flutter_ijkplayer.dart';
 import 'package:flutter_svg/flutter_svg.dart';
+import 'package:outline_material_icons/outline_material_icons.dart';
 import 'package:photo_view/photo_view.dart';
 import 'package:tuple/tuple.dart';
 
@@ -101,6 +103,11 @@ class ImageView extends StatelessWidget {
                 image: uriImage,
               )
             : thumbnailLoadingBuilder(context),
+        loadFailedChild: EmptyContent(
+          icon: OMIcons.errorOutline,
+          text: 'Oops!',
+          alignment: Alignment.center,
+        ),
         backgroundDecoration: backgroundDecoration,
         scaleStateChangedCallback: onScaleChanged,
         minScale: PhotoViewComputedScale.contained,

pubspec.lock

@@ -399,6 +399,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "2.0.0"
+  streams_channel:
+    dependency: "direct main"
+    description:
+      name: streams_channel
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.3.0"
   string_scanner:
     dependency: transitive
     description:

pubspec.yaml

@@ -70,6 +70,7 @@ dependencies:
   screen:
   shared_preferences:
   sqflite:
+  streams_channel:
   tuple:
   uuid: