Fix single frame image is decoded even cached (#82533)

* Fix single frame image is decoded even cached

* Add MultiFrameImageStreamCompleter decode test for one frame image

packages/flutter/lib/src/painting/image_stream.dart

@@ -974,7 +974,7 @@ class MultiFrameImageStreamCompleter extends ImageStreamCompleter {
 
   @override
   void addListener(ImageStreamListener listener) {
-    if (!hasListeners && _codec != null)
+    if (!hasListeners && _codec != null && (_currentImage == null || _codec!.frameCount > 1))
       _decodeNextFrameAndSchedule();
     super.addListener(listener);
   }

packages/flutter/test/painting/fake_codec.dart

@@ -19,6 +19,7 @@ class FakeCodec implements ui.Codec {
   final int _repetitionCount;
   final List<ui.FrameInfo> _frameInfos;
   int _nextFrame = 0;
+  int _numFramesAsked = 0;
 
   /// Creates a FakeCodec from encoded image data.
   ///
@@ -38,8 +39,11 @@ class FakeCodec implements ui.Codec {
   @override
   int get repetitionCount => _repetitionCount;
 
+  int get numFramesAsked => _numFramesAsked;
+
   @override
   Future<ui.FrameInfo> getNextFrame() {
+    _numFramesAsked += 1;
     final SynchronousFuture<ui.FrameInfo> result =
       SynchronousFuture<ui.FrameInfo>(_frameInfos[_nextFrame]);
     _nextFrame = (_nextFrame + 1) % _frameCount;

packages/flutter/test/painting/image_stream_test.dart

@@ -3,12 +3,16 @@
 // found in the LICENSE file.
 
 import 'dart:async';
+import 'dart:typed_data';
 import 'dart:ui';
 
 import 'package:flutter/painting.dart';
 import 'package:flutter/scheduler.dart' show timeDilation, SchedulerBinding;
 import 'package:flutter_test/flutter_test.dart';
 
+import '../image_data.dart';
+import 'fake_codec.dart';
+
 class FakeFrameInfo implements FrameInfo {
   const FakeFrameInfo(this._duration, this._image);
 
@@ -780,6 +784,32 @@ void main() {
     handle.dispose();
   });
 
+  test('MultiFrameImageStreamCompleter - one frame image should only be decoded once', () async {
+    final FakeCodec oneFrameCodec = await FakeCodec.fromData(Uint8List.fromList(kTransparentImage));
+    final Completer<Codec> codecCompleter = Completer<Codec>();
+    final Completer<void> decodeCompleter = Completer<void>();
+    final ImageStreamCompleter imageStream = MultiFrameImageStreamCompleter(
+      codec: codecCompleter.future,
+      scale: 1.0,
+    );
+    final ImageStreamListener imageListener = ImageStreamListener((ImageInfo info, bool syncCall) {
+      decodeCompleter.complete();
+    });
+
+    imageStream.keepAlive();  // do not dispose
+    imageStream.addListener(imageListener);
+    codecCompleter.complete(oneFrameCodec);
+    await decodeCompleter.future;
+
+    imageStream.removeListener(imageListener);
+    expect(oneFrameCodec.numFramesAsked, 1);
+
+    // Adding a new listener for decoded imageSteam, the one frame image should
+    // not be decoded again.
+    imageStream.addListener(ImageStreamListener((ImageInfo info, bool syncCall) {}));
+    expect(oneFrameCodec.numFramesAsked, 1);
+  });  // https://github.com/flutter/flutter/issues/82532
+
   // TODO(amirh): enable this once WidgetTester supports flushTimers.
   // https://github.com/flutter/flutter/issues/30344
   // testWidgets('remove and add listener before a delayed frame is scheduled', (WidgetTester tester) async {