restored streaming fullscreen image, with chunk events

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

@@ -108,9 +108,7 @@ public class ImageByteStreamHandler implements EventChannel.StreamHandler {
             } else {
                 try (InputStream is = cr.openInputStream(uri)) {
                     if (is != null) {
-                        // TODO TLAD streaming would allow chunk events, but in practice Flutter blocks every time we send a chunk
-//                        streamBytes(is);
-                        success(getBytes(is));
+                        streamBytes(is);
                     } else {
                         error("getImage-image-read-null", "failed to get image from uri=" + uri, null);
                     }
@@ -123,7 +121,7 @@ public class ImageByteStreamHandler implements EventChannel.StreamHandler {
     }
 
     private void streamBytes(InputStream inputStream) throws IOException {
-        int bufferSize = 2 << 17; // ~250k
+        int bufferSize = 2 << 17; // 256kB
         byte[] buffer = new byte[bufferSize];
         int len;
         while ((len = inputStream.read(buffer)) != -1) {
@@ -133,17 +131,4 @@ public class ImageByteStreamHandler implements EventChannel.StreamHandler {
             success(sub);
         }
     }
-
-    // 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();
-    }
 }

lib/services/image_file_service.dart

@@ -36,15 +36,28 @@ class ImageFileService {
     return null;
   }
 
-  static Future<Uint8List> getImage(String uri, String mimeType) {
+  static Future<Uint8List> getImage(String uri, String mimeType, {int expectedContentLength, BytesReceivedCallback onBytesReceived}) {
     try {
       final completer = Completer<Uint8List>.sync();
       final sink = _OutputBuffer();
+      var bytesReceived = 0;
       byteChannel.receiveBroadcastStream(<String, dynamic>{
         'uri': uri,
         'mimeType': mimeType,
       }).listen(
-        (chunk) => sink.add(chunk as Uint8List),
+        (data) {
+          final chunk = data as Uint8List;
+          sink.add(chunk);
+          if (onBytesReceived != null) {
+            bytesReceived += chunk.length;
+            try {
+              onBytesReceived(bytesReceived, expectedContentLength);
+            } catch (error, stackTrace) {
+              completer.completeError(error, stackTrace);
+              return;
+            }
+          }
+        },
         onError: completer.completeError,
         onDone: () {
           sink.close();
@@ -203,7 +216,10 @@ class MoveOpEvent extends ImageOpEvent {
   }
 }
 
-// copied from `consolidateHttpClientResponseBytes` in flutter/foundation
+// cf flutter/foundation `consolidateHttpClientResponseBytes`
+typedef BytesReceivedCallback = void Function(int cumulative, int total);
+
+// cf flutter/foundation `consolidateHttpClientResponseBytes`
 class _OutputBuffer extends ByteConversionSinkBase {
   List<List<int>> _chunks = <List<int>>[];
   int _contentLength = 0;
@@ -223,8 +239,8 @@ class _OutputBuffer extends ByteConversionSinkBase {
       return;
     }
     _bytes = Uint8List(_contentLength);
-    int offset = 0;
-    for (final List<int> chunk in _chunks) {
+    var offset = 0;
+    for (final chunk in _chunks) {
       _bytes.setRange(offset, offset + chunk.length, chunk);
       offset += chunk.length;
     }

lib/widgets/album/thumbnail/raster.dart

@@ -116,6 +116,7 @@ class _ThumbnailRasterImageState extends State<ThumbnailRasterImage> {
                 final imageProvider = UriImage(
                   uri: entry.uri,
                   mimeType: entry.mimeType,
+                  expectedContentLength: entry.sizeBytes,
                 );
                 if (imageCache.statusForKey(imageProvider).keepAlive) {
                   heroImageProvider = imageProvider;

lib/widgets/common/image_providers/uri_image_provider.dart

@@ -1,20 +1,23 @@
+import 'dart:async';
 import 'dart:typed_data';
 import 'dart:ui' as ui show Codec;
 
 import 'package:aves/services/image_file_service.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
+import 'package:pedantic/pedantic.dart';
 
 class UriImage extends ImageProvider<UriImage> {
   const UriImage({
     @required this.uri,
     @required this.mimeType,
+    this.expectedContentLength,
     this.scale = 1.0,
   })  : assert(uri != null),
         assert(scale != null);
 
   final String uri, mimeType;
-
+  final int expectedContentLength;
   final double scale;
 
   @override
@@ -24,20 +27,37 @@ class UriImage extends ImageProvider<UriImage> {
 
   @override
   ImageStreamCompleter load(UriImage key, DecoderCallback decode) {
+    final chunkEvents = StreamController<ImageChunkEvent>();
+
     return MultiFrameImageStreamCompleter(
-      codec: _loadAsync(key, decode),
+      codec: _loadAsync(key, decode, chunkEvents),
       scale: key.scale,
+      chunkEvents: chunkEvents.stream,
       informationCollector: () sync* {
         yield ErrorDescription('uri=$uri, mimeType=$mimeType');
       },
     );
   }
 
-  Future<ui.Codec> _loadAsync(UriImage key, DecoderCallback decode) async {
+  Future<ui.Codec> _loadAsync(UriImage key, DecoderCallback decode, StreamController<ImageChunkEvent> chunkEvents) async {
     assert(key == this);
 
-    final bytes = await ImageFileService.getImage(uri, mimeType);
-    return await decode(bytes ?? Uint8List(0));
+    try {
+      final bytes = await ImageFileService.getImage(
+        uri,
+        mimeType,
+        expectedContentLength: expectedContentLength,
+        onBytesReceived: (cumulative, total) {
+          chunkEvents.add(ImageChunkEvent(
+            cumulativeBytesLoaded: cumulative,
+            expectedTotalBytes: total,
+          ));
+        },
+      );
+      return await decode(bytes ?? Uint8List(0));
+    } finally {
+      unawaited(chunkEvents.close());
+    }
   }
 
   @override

lib/widgets/fullscreen/image_view.dart

@@ -95,6 +95,7 @@ class ImageView extends StatelessWidget {
       final uriImage = UriImage(
         uri: entry.uri,
         mimeType: entry.mimeType,
+        expectedContentLength: entry.sizeBytes,
       );
       child = PhotoView(
         // key includes size and orientation to refresh when the image is rotated

lib/widgets/fullscreen/video_view.dart

@@ -98,7 +98,11 @@ class AvesVideoState extends State<AvesVideo> {
                   backgroundColor: Colors.transparent,
                 )
               : Image(
-                  image: UriImage(uri: entry.uri, mimeType: entry.mimeType),
+                  image: UriImage(
+                    uri: entry.uri,
+                    mimeType: entry.mimeType,
+                    expectedContentLength: entry.sizeBytes,
+                  ),
                   width: entry.width.toDouble(),
                   height: entry.height.toDouble(),
                 );