Add error callbacks to other image resolving code (#53329)

packages/flutter/lib/src/material/circle_avatar.dart

@@ -17,6 +17,9 @@ import 'theme_data.dart';
 /// such an image, the user's initials. A given user's initials should
 /// always be paired with the same background color, for consistency.
 ///
+/// The [onBackgroundImageError] parameter must be null if the [backgroundImage]
+/// is null.
+///
 /// {@tool snippet}
 ///
 /// If the avatar is to have an image, the image should be specified in the
@@ -57,11 +60,13 @@ class CircleAvatar extends StatelessWidget {
     this.child,
     this.backgroundColor,
     this.backgroundImage,
+    this.onBackgroundImageError,
     this.foregroundColor,
     this.radius,
     this.minRadius,
     this.maxRadius,
   }) : assert(radius == null || (minRadius == null && maxRadius == null)),
+       assert(backgroundImage != null || onBackgroundImageError == null),
        super(key: key);
 
   /// The widget below this widget in the tree.
@@ -93,6 +98,10 @@ class CircleAvatar extends StatelessWidget {
   /// If the [CircleAvatar] is to have the user's initials, use [child] instead.
   final ImageProvider backgroundImage;
 
+  /// An optional error callback for errors emitted when loading
+  /// [backgroundImage].
+  final ImageErrorListener onBackgroundImageError;
+
   /// The size of the avatar, expressed as the radius (half the diameter).
   ///
   /// If [radius] is specified, then neither [minRadius] nor [maxRadius] may be
@@ -200,7 +209,11 @@ class CircleAvatar extends StatelessWidget {
       decoration: BoxDecoration(
         color: effectiveBackgroundColor,
         image: backgroundImage != null
-          ? DecorationImage(image: backgroundImage, fit: BoxFit.cover)
+          ? DecorationImage(
+              image: backgroundImage,
+              onError: onBackgroundImageError,
+              fit: BoxFit.cover,
+            )
           : null,
         shape: BoxShape.circle,
       ),

packages/flutter/lib/src/material/ink_decoration.dart

@@ -145,7 +145,8 @@ class Ink extends StatefulWidget {
   ///
   /// The `image` argument must not be null. If there is no
   /// intention to render anything on this image, consider using a
-  /// [Container] with a [BoxDecoration.image] instead.
+  /// [Container] with a [BoxDecoration.image] instead. The `onImageError`
+  /// argument may be provided to listen for errors when resolving the image.
   ///
   /// The `alignment`, `repeat`, and `matchTextDirection` arguments must not
   /// be null either, but they have default values.
@@ -155,6 +156,7 @@ class Ink extends StatefulWidget {
     Key key,
     this.padding,
     @required ImageProvider image,
+    ImageErrorListener onImageError,
     ColorFilter colorFilter,
     BoxFit fit,
     AlignmentGeometry alignment = Alignment.center,
@@ -172,6 +174,7 @@ class Ink extends StatefulWidget {
        decoration = BoxDecoration(
          image: DecorationImage(
            image: image,
+           onError: onImageError,
            colorFilter: colorFilter,
            fit: fit,
            alignment: alignment,

packages/flutter/lib/src/material/switch.dart

@@ -71,7 +71,9 @@ class Switch extends StatefulWidget {
     this.inactiveThumbColor,
     this.inactiveTrackColor,
     this.activeThumbImage,
+    this.onActiveThumbImageError,
     this.inactiveThumbImage,
+    this.onInactiveThumbImageError,
     this.materialTapTargetSize,
     this.dragStartBehavior = DragStartBehavior.start,
     this.focusColor,
@@ -80,6 +82,8 @@ class Switch extends StatefulWidget {
     this.autofocus = false,
   })  : _switchType = _SwitchType.material,
         assert(dragStartBehavior != null),
+        assert(activeThumbImage != null || onActiveThumbImageError == null),
+        assert(inactiveThumbImage != null || onInactiveThumbImageError == null),
         super(key: key);
 
   /// Creates a [CupertinoSwitch] if the target platform is iOS, creates a
@@ -87,7 +91,8 @@ class Switch extends StatefulWidget {
   ///
   /// If a [CupertinoSwitch] is created, the following parameters are
   /// ignored: [activeTrackColor], [inactiveThumbColor], [inactiveTrackColor],
-  /// [activeThumbImage], [inactiveThumbImage], [materialTapTargetSize].
+  /// [activeThumbImage], [onActiveThumbImageError], [inactiveThumbImage],
+  /// [onInactiveImageThumbError], [materialTapTargetSize].
   ///
   /// The target platform is based on the current [Theme]: [ThemeData.platform].
   const Switch.adaptive({
@@ -99,7 +104,9 @@ class Switch extends StatefulWidget {
     this.inactiveThumbColor,
     this.inactiveTrackColor,
     this.activeThumbImage,
+    this.onActiveThumbImageError,
     this.inactiveThumbImage,
+    this.onInactiveThumbImageError,
     this.materialTapTargetSize,
     this.dragStartBehavior = DragStartBehavior.start,
     this.focusColor,
@@ -107,6 +114,8 @@ class Switch extends StatefulWidget {
     this.focusNode,
     this.autofocus = false,
   })  : assert(autofocus != null),
+        assert(activeThumbImage != null || onActiveThumbImageError == null),
+        assert(inactiveThumbImage != null || onInactiveThumbImageError == null),
         _switchType = _SwitchType.adaptive,
         super(key: key);
 
@@ -170,11 +179,19 @@ class Switch extends StatefulWidget {
   /// Ignored if this switch is created with [Switch.adaptive].
   final ImageProvider activeThumbImage;
 
+  /// An optional error callback for errors emitted when loading
+  /// [activeThumbImage].
+  final ImageErrorListener onActiveThumbImageError;
+
   /// An image to use on the thumb of this switch when the switch is off.
   ///
   /// Ignored if this switch is created with [Switch.adaptive].
   final ImageProvider inactiveThumbImage;
 
+  /// An optional error callback for errors emitted when loading
+  /// [inactiveThumbImage].
+  final ImageErrorListener onInactiveThumbImageError;
+
   /// Configures the minimum size of the tap target.
   ///
   /// Defaults to [ThemeData.materialTapTargetSize].
@@ -311,7 +328,9 @@ class _SwitchState extends State<Switch> with TickerProviderStateMixin {
             hoverColor: hoverColor,
             focusColor: focusColor,
             activeThumbImage: widget.activeThumbImage,
+            onActiveThumbImageError: widget.onActiveThumbImageError,
             inactiveThumbImage: widget.inactiveThumbImage,
+            onInactiveThumbImageError: widget.onInactiveThumbImageError,
             activeTrackColor: activeTrackColor,
             inactiveTrackColor: inactiveTrackColor,
             configuration: createLocalImageConfiguration(context),
@@ -381,7 +400,9 @@ class _SwitchRenderObjectWidget extends LeafRenderObjectWidget {
     this.hoverColor,
     this.focusColor,
     this.activeThumbImage,
+    this.onActiveThumbImageError,
     this.inactiveThumbImage,
+    this.onInactiveThumbImageError,
     this.activeTrackColor,
     this.inactiveTrackColor,
     this.configuration,
@@ -399,7 +420,9 @@ class _SwitchRenderObjectWidget extends LeafRenderObjectWidget {
   final Color hoverColor;
   final Color focusColor;
   final ImageProvider activeThumbImage;
+  final ImageErrorListener onActiveThumbImageError;
   final ImageProvider inactiveThumbImage;
+  final ImageErrorListener onInactiveThumbImageError;
   final Color activeTrackColor;
   final Color inactiveTrackColor;
   final ImageConfiguration configuration;
@@ -420,7 +443,9 @@ class _SwitchRenderObjectWidget extends LeafRenderObjectWidget {
       hoverColor: hoverColor,
       focusColor: focusColor,
       activeThumbImage: activeThumbImage,
+      onActiveThumbImageError: onActiveThumbImageError,
       inactiveThumbImage: inactiveThumbImage,
+      onInactiveThumbImageError: onInactiveThumbImageError,
       activeTrackColor: activeTrackColor,
       inactiveTrackColor: inactiveTrackColor,
       configuration: configuration,
@@ -442,7 +467,9 @@ class _SwitchRenderObjectWidget extends LeafRenderObjectWidget {
       ..hoverColor = hoverColor
       ..focusColor = focusColor
       ..activeThumbImage = activeThumbImage
+      ..onActiveThumbImageError = onActiveThumbImageError
       ..inactiveThumbImage = inactiveThumbImage
+      ..onInactiveThumbImageError = onInactiveThumbImageError
       ..activeTrackColor = activeTrackColor
       ..inactiveTrackColor = inactiveTrackColor
       ..configuration = configuration
@@ -464,7 +491,9 @@ class _RenderSwitch extends RenderToggleable {
     Color hoverColor,
     Color focusColor,
     ImageProvider activeThumbImage,
+    ImageErrorListener onActiveThumbImageError,
     ImageProvider inactiveThumbImage,
+    ImageErrorListener onInactiveThumbImageError,
     Color activeTrackColor,
     Color inactiveTrackColor,
     ImageConfiguration configuration,
@@ -477,7 +506,9 @@ class _RenderSwitch extends RenderToggleable {
     @required this.state,
   }) : assert(textDirection != null),
        _activeThumbImage = activeThumbImage,
+       _onActiveThumbImageError = onActiveThumbImageError,
        _inactiveThumbImage = inactiveThumbImage,
+       _onInactiveThumbImageError = onInactiveThumbImageError,
        _activeTrackColor = activeTrackColor,
        _inactiveTrackColor = inactiveTrackColor,
        _configuration = configuration,
@@ -511,6 +542,16 @@ class _RenderSwitch extends RenderToggleable {
     markNeedsPaint();
   }
 
+  ImageErrorListener get onActiveThumbImageError => _onActiveThumbImageError;
+  ImageErrorListener _onActiveThumbImageError;
+  set onActiveThumbImageError(ImageErrorListener value) {
+    if (value == _onActiveThumbImageError) {
+      return;
+    }
+    _onActiveThumbImageError = value;
+    markNeedsPaint();
+  }
+
   ImageProvider get inactiveThumbImage => _inactiveThumbImage;
   ImageProvider _inactiveThumbImage;
   set inactiveThumbImage(ImageProvider value) {
@@ -520,6 +561,16 @@ class _RenderSwitch extends RenderToggleable {
     markNeedsPaint();
   }
 
+  ImageErrorListener get onInactiveThumbImageError => _onInactiveThumbImageError;
+  ImageErrorListener _onInactiveThumbImageError;
+  set onInactiveThumbImageError(ImageErrorListener value) {
+    if (value == _onInactiveThumbImageError) {
+      return;
+    }
+    _onInactiveThumbImageError = value;
+    markNeedsPaint();
+  }
+
   Color get activeTrackColor => _activeTrackColor;
   Color _activeTrackColor;
   set activeTrackColor(Color value) {
@@ -642,12 +693,13 @@ class _RenderSwitch extends RenderToggleable {
 
   Color _cachedThumbColor;
   ImageProvider _cachedThumbImage;
+  ImageErrorListener _cachedThumbErrorListener;
   BoxPainter _cachedThumbPainter;
 
-  BoxDecoration _createDefaultThumbDecoration(Color color, ImageProvider image) {
+  BoxDecoration _createDefaultThumbDecoration(Color color, ImageProvider image, ImageErrorListener errorListener) {
     return BoxDecoration(
       color: color,
-      image: image == null ? null : DecorationImage(image: image),
+      image: image == null ? null : DecorationImage(image: image, onError: errorListener),
       shape: BoxShape.circle,
       boxShadow: kElevationToShadow[1],
     );
@@ -698,6 +750,10 @@ class _RenderSwitch extends RenderToggleable {
       ? (currentValue < 0.5 ? inactiveThumbImage : activeThumbImage)
       : inactiveThumbImage;
 
+    final ImageErrorListener thumbErrorListener = isEnabled
+      ? (currentValue < 0.5 ? onInactiveThumbImageError : onActiveThumbImageError)
+      : onInactiveThumbImageError;
+
     // Paint the track
     final Paint paint = Paint()
       ..color = trackColor;
@@ -721,10 +777,11 @@ class _RenderSwitch extends RenderToggleable {
     try {
       _isPainting = true;
       BoxPainter thumbPainter;
-      if (_cachedThumbPainter == null || thumbColor != _cachedThumbColor || thumbImage != _cachedThumbImage) {
+      if (_cachedThumbPainter == null || thumbColor != _cachedThumbColor || thumbImage != _cachedThumbImage || thumbErrorListener != _cachedThumbErrorListener) {
         _cachedThumbColor = thumbColor;
         _cachedThumbImage = thumbImage;
-        _cachedThumbPainter = _createDefaultThumbDecoration(thumbColor, thumbImage).createBoxPainter(_handleDecorationChanged);
+        _cachedThumbErrorListener = thumbErrorListener;
+        _cachedThumbPainter = _createDefaultThumbDecoration(thumbColor, thumbImage, thumbErrorListener).createBoxPainter(_handleDecorationChanged);
       }
       thumbPainter = _cachedThumbPainter;
 

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

@@ -40,6 +40,7 @@ class DecorationImage {
   /// must not be null.
   const DecorationImage({
     @required this.image,
+    this.onError,
     this.colorFilter,
     this.fit,
     this.alignment = Alignment.center,
@@ -57,6 +58,9 @@ class DecorationImage {
   /// application) or a [NetworkImage] (for an image obtained from the network).
   final ImageProvider image;
 
+  /// An optional error callback for errors emitted when loading [image].
+  final ImageErrorListener onError;
+
   /// A color filter to apply to the image before painting it.
   final ColorFilter colorFilter;
 
@@ -239,7 +243,10 @@ class DecorationImagePainter {
 
     final ImageStream newImageStream = _details.image.resolve(configuration);
     if (newImageStream.key != _imageStream?.key) {
-      final ImageStreamListener listener = ImageStreamListener(_handleImage);
+      final ImageStreamListener listener = ImageStreamListener(
+        _handleImage,
+        onError: _details.onError,
+      );
       _imageStream?.removeListener(listener);
       _imageStream = newImageStream;
       _imageStream.addListener(listener);
@@ -286,7 +293,10 @@ class DecorationImagePainter {
   /// After this method has been called, the object is no longer usable.
   @mustCallSuper
   void dispose() {
-    _imageStream?.removeListener(ImageStreamListener(_handleImage));
+    _imageStream?.removeListener(ImageStreamListener(
+      _handleImage,
+      onError: _details.onError,
+    ));
   }
 
   @override

packages/flutter/lib/src/widgets/fade_in_image.dart

@@ -77,7 +77,9 @@ class FadeInImage extends StatelessWidget {
   const FadeInImage({
     Key key,
     @required this.placeholder,
+    this.placeholderErrorBuilder,
     @required this.image,
+    this.imageErrorBuilder,
     this.excludeFromSemantics = false,
     this.imageSemanticLabel,
     this.fadeOutDuration = const Duration(milliseconds: 300),
@@ -132,7 +134,9 @@ class FadeInImage extends StatelessWidget {
   FadeInImage.memoryNetwork({
     Key key,
     @required Uint8List placeholder,
+    this.placeholderErrorBuilder,
     @required String image,
+    this.imageErrorBuilder,
     double placeholderScale = 1.0,
     double imageScale = 1.0,
     this.excludeFromSemantics = false,
@@ -200,7 +204,9 @@ class FadeInImage extends StatelessWidget {
   FadeInImage.assetNetwork({
     Key key,
     @required String placeholder,
+    this.placeholderErrorBuilder,
     @required String image,
+    this.imageErrorBuilder,
     AssetBundle bundle,
     double placeholderScale,
     double imageScale = 1.0,
@@ -239,9 +245,24 @@ class FadeInImage extends StatelessWidget {
   /// Image displayed while the target [image] is loading.
   final ImageProvider placeholder;
 
+  /// A builder function that is called if an error occurs during placeholder
+  /// image loading.
+  ///
+  /// If this builder is not provided, any exceptions will be reported to
+  /// [FlutterError.onError]. If it is provided, the caller should either handle
+  /// the exception by providing a replacement widget, or rethrow the exception.
+  final ImageErrorWidgetBuilder placeholderErrorBuilder;
+
   /// The target image that is displayed once it has loaded.
   final ImageProvider image;
 
+  /// A builder function that is called if an error occurs during image loading.
+  ///
+  /// If this builder is not provided, any exceptions will be reported to
+  /// [FlutterError.onError]. If it is provided, the caller should either handle
+  /// the exception by providing a replacement widget, or rethrow the exception.
+  final ImageErrorWidgetBuilder imageErrorBuilder;
+
   /// The duration of the fade-out animation for the [placeholder].
   final Duration fadeOutDuration;
 
@@ -337,11 +358,13 @@ class FadeInImage extends StatelessWidget {
 
   Image _image({
     @required ImageProvider image,
+    ImageErrorWidgetBuilder errorBuilder,
     ImageFrameBuilder frameBuilder,
   }) {
     assert(image != null);
     return Image(
       image: image,
+      errorBuilder: errorBuilder,
       frameBuilder: frameBuilder,
       width: width,
       height: height,
@@ -358,12 +381,13 @@ class FadeInImage extends StatelessWidget {
   Widget build(BuildContext context) {
     Widget result = _image(
       image: image,
+      errorBuilder: imageErrorBuilder,
       frameBuilder: (BuildContext context, Widget child, int frame, bool wasSynchronouslyLoaded) {
         if (wasSynchronouslyLoaded)
           return child;
         return _AnimatedFadeOutFadeIn(
           target: child,
-          placeholder: _image(image: placeholder),
+          placeholder: _image(image: placeholder, errorBuilder: placeholderErrorBuilder),
           isTargetLoaded: frame != null,
           fadeInDuration: fadeInDuration,
           fadeOutDuration: fadeOutDuration,

packages/flutter/test/painting/decoration_test.dart

@@ -40,6 +40,22 @@ class SynchronousTestImageProvider extends ImageProvider<int> {
   }
 }
 
+class SynchronousErrorTestImageProvider extends ImageProvider<int> {
+  const SynchronousErrorTestImageProvider(this.throwable);
+
+  final Object throwable;
+
+  @override
+  Future<int> obtainKey(ImageConfiguration configuration) {
+    throw throwable;
+  }
+
+  @override
+  ImageStreamCompleter load(int key, DecoderCallback decode) {
+    throw throwable;
+  }
+}
+
 class AsyncTestImageProvider extends ImageProvider<int> {
   @override
   Future<int> obtainKey(ImageConfiguration configuration) {
@@ -269,6 +285,26 @@ void main() {
     );
   });
 
+  test('DecorationImage - error listener', () async {
+    String exception;
+    final DecorationImage backgroundImage = DecorationImage(
+      image: const SynchronousErrorTestImageProvider('threw'),
+      onError: (dynamic error, StackTrace stackTrace) {
+        exception = error as String;
+      }
+    );
+
+    backgroundImage.createPainter(() { }).paint(
+      TestCanvas(),
+      Rect.largest,
+      Path(),
+      ImageConfiguration.empty,
+    );
+    // Yield so that the exception callback gets called before we check it.
+    await null;
+    expect(exception, 'threw');
+  });
+
   test('BoxDecoration.lerp - shapes', () {
     // We don't lerp the shape, we just switch from one to the other at t=0.5.
     // (Use a ShapeDecoration and ShapeBorder if you want to lerp the shapes...)