fixes FadeInImage for an edge case (#111035)

werainkhatri · web-flow · commit 165cb0b9862c · 2022-09-08T02:41:31.000Z
diff --git a/packages/flutter/lib/src/widgets/fade_in_image.dart b/packages/flutter/lib/src/widgets/fade_in_image.dart
@@ -562,7 +562,8 @@ class _AnimatedFadeOutFadeInState extends ImplicitlyAnimatedWidgetState<_Animate
 
   @override
   Widget build(BuildContext context) {
-    if (widget.wasSynchronouslyLoaded || _placeholderOpacityAnimation!.isCompleted) {
+    if (widget.wasSynchronouslyLoaded ||
+        (_placeholderOpacityAnimation?.isCompleted ?? true)) {
       return widget.target;
     }
 
diff --git a/packages/flutter/test/widgets/fade_in_image_test.dart b/packages/flutter/test/widgets/fade_in_image_test.dart
@@ -199,6 +199,44 @@ Future<void> main() async {
       expect(parts.target.opacity, 1);
     });
 
+    // Regression test for https://github.com/flutter/flutter/issues/111011
+    testWidgets("FadeInImage's image obeys gapless playback when first image is cached but second isn't",
+            (WidgetTester tester) async {
+      final TestImageProvider placeholderProvider = TestImageProvider(placeholderImage);
+      final TestImageProvider imageProvider = TestImageProvider(targetImage);
+      final TestImageProvider secondImageProvider = TestImageProvider(replacementImage);
+
+      // Pre-cache the initial image.
+      imageProvider.resolve(ImageConfiguration.empty);
+      imageProvider.complete();
+      placeholderProvider.complete();
+
+      await tester.pumpWidget(FadeInImage(
+        placeholder: placeholderProvider,
+        image: imageProvider,
+      ));
+      await tester.pumpAndSettle();
+
+      await tester.pumpWidget(FadeInImage(
+        placeholder: placeholderProvider,
+        image: secondImageProvider,
+      ));
+
+      FadeInImageParts parts = findFadeInImage(tester);
+      // Continually shows previously loaded image until the new image provider provides the image.
+      expect(parts.placeholder, isNull);
+      expect(parts.target.rawImage.image!.isCloneOf(targetImage), isTrue);
+      expect(parts.target.opacity, 1);
+
+      // Now, provide the image.
+      secondImageProvider.complete();
+      await tester.pump();
+
+      parts = findFadeInImage(tester);
+      expect(parts.target.rawImage.image!.isCloneOf(replacementImage), isTrue);
+      expect(parts.target.opacity, 1);
+    });
+
     testWidgets("FadeInImage's placeholder obeys gapless playback", (WidgetTester tester) async {
       final TestImageProvider placeholderProvider = TestImageProvider(placeholderImage);
       final TestImageProvider secondPlaceholderProvider = TestImageProvider(replacementImage);

Original file line number	Diff line number	Diff line change
`@@ -562,7 +562,8 @@ class _AnimatedFadeOutFadeInState extends ImplicitlyAnimatedWidgetState<_Animate`
`562`	`562`
`563`	`563`	`@override`
`564`	`564`	`Widget build(BuildContext context) {`
`565`		`- if (widget.wasSynchronouslyLoaded \|\| _placeholderOpacityAnimation!.isCompleted) {`
	`565`	`+ if (widget.wasSynchronouslyLoaded \|\|`
	`566`	`+ (_placeholderOpacityAnimation?.isCompleted ?? true)) {`
`566`	`567`	`return widget.target;`
`567`	`568`	`}`
`568`	`569`