Adds wide gamut saveLayer integration test (#120131)

* Added wide gamut integration test that uses save layers.

* updated the test to support bgra too

* analysis errors

* switched blend mode to multiply to avoid future optimizations

dev/integration_tests/wide_gamut_test/integration_test/app_test.dart

@@ -23,40 +23,80 @@ bool _isAlmost(double x, double y, double epsilon) {
   return (x - y).abs() < epsilon;
 }
 
+bool _findDeepRedBGRA10(Uint8List bytes, int width, int height) {
+  final ByteData byteData = ByteData.sublistView(bytes);
+  expect(bytes.lengthInBytes, width * height * 8);
+  expect(bytes.lengthInBytes, byteData.lengthInBytes);
+  bool foundDeepRed = false;
+  for (int i = 0; i < bytes.lengthInBytes; i += 8) {
+    final int pixel = byteData.getUint64(i, Endian.host);
+    final double blue = _decodeBGR10((pixel >> 6) & 0x3ff);
+    final double green = _decodeBGR10((pixel >> 22) & 0x3ff);
+    final double red = _decodeBGR10((pixel >> 38) & 0x3ff);
+    if (_isAlmost(red, 1.0931, 0.01) &&
+        _isAlmost(green, -0.2268, 0.01) &&
+        _isAlmost(blue, -0.1501, 0.01)) {
+      foundDeepRed = true;
+    }
+  }
+  return foundDeepRed;
+}
+
+bool _findDeepRedBGR10(Uint8List bytes, int width, int height) {
+  final ByteData byteData = ByteData.sublistView(bytes);
+  expect(bytes.lengthInBytes, width * height * 4);
+  expect(bytes.lengthInBytes, byteData.lengthInBytes);
+  bool foundDeepRed = false;
+  for (int i = 0; i < bytes.lengthInBytes; i += 4) {
+    final int pixel = byteData.getUint32(i, Endian.host);
+    final double blue = _decodeBGR10(pixel & 0x3ff);
+    final double green = _decodeBGR10((pixel >> 10) & 0x3ff);
+    final double red = _decodeBGR10((pixel >> 20) & 0x3ff);
+    if (_isAlmost(red, 1.0931, 0.01) &&
+        _isAlmost(green, -0.2268, 0.01) &&
+        _isAlmost(blue, -0.1501, 0.01)) {
+      foundDeepRed = true;
+    }
+  }
+  return foundDeepRed;
+}
+
+bool _findDeepRed(List<Object?> result) {
+  expect(result, isNotNull);
+  expect(result.length, 4);
+  final int width = (result[0] as int?)!;
+  final int height = (result[1] as int?)!;
+  final String format = (result[2] as String?)!;
+  if (format == 'MTLPixelFormatBGR10_XR') {
+    return _findDeepRedBGR10((result[3] as Uint8List?)!, width, height);
+  } else if (format == 'MTLPixelFormatBGRA10_XR') {
+    return _findDeepRedBGRA10((result[3] as Uint8List?)!, width, height);
+  } else {
+    fail('Unsupported pixel format: $format');
+  }
+}
+
 void main() {
   IntegrationTestWidgetsFlutterBinding.ensureInitialized();
 
   group('end-to-end test', () {
     testWidgets('look for display p3 deepest red', (WidgetTester tester) async {
-      app.main();
+      app.run(app.Setup.image);
+      await tester.pumpAndSettle(const Duration(seconds: 2));
+
+      const MethodChannel channel = MethodChannel('flutter/screenshot');
+      final List<Object?> result =
+          await channel.invokeMethod('test') as List<Object?>;
+      expect(_findDeepRed(result), isTrue);
+    });
+    testWidgets('look for display p3 deepest red', (WidgetTester tester) async {
+      app.run(app.Setup.canvasSaveLayer);
       await tester.pumpAndSettle(const Duration(seconds: 2));
 
       const MethodChannel channel = MethodChannel('flutter/screenshot');
       final List<Object?> result =
           await channel.invokeMethod('test') as List<Object?>;
-      expect(result, isNotNull);
-      expect(result.length, 4);
-      final int width = (result[0] as int?)!;
-      final int height = (result[1] as int?)!;
-      final String format = (result[2] as String?)!;
-      expect(format, 'MTLPixelFormatBGR10_XR');
-      final Uint8List bytes = (result[3] as Uint8List?)!;
-      final ByteData byteData = ByteData.sublistView(bytes);
-      expect(bytes.lengthInBytes, width * height * 4);
-      expect(bytes.lengthInBytes, byteData.lengthInBytes);
-      bool foundDeepRed = false;
-      for (int i = 0; i < bytes.lengthInBytes; i += 4) {
-        final int pixel = byteData.getUint32(i, Endian.host);
-        final double blue = _decodeBGR10(pixel & 0x3ff);
-        final double green = _decodeBGR10((pixel >> 10) & 0x3ff);
-        final double red = _decodeBGR10((pixel >> 20) & 0x3ff);
-        if (_isAlmost(red, 1.0931, 0.01) &&
-            _isAlmost(green, -0.2268, 0.01) &&
-            _isAlmost(blue, -0.1501, 0.01)) {
-          foundDeepRed = true;
-        }
-      }
-      expect(foundDeepRed, isTrue);
+      expect(_findDeepRed(result), isTrue);
     });
   });
 }

dev/integration_tests/wide_gamut_test/lib/main.dart

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 import 'dart:convert' show base64Decode;
+import 'dart:ui' as ui;
 import 'package:flutter/material.dart';
 
 /// A 100x100 png in Display P3 colorspace.
@@ -63,12 +64,21 @@ const String _displayP3Logo =
     'ElWKtuy2OXm9QtxYmoawGJUL3jcwHpiBNxagGJUL3jcwHpiBNxagGJUL3jcwHpiBNxagGJUL3j'
     'cwHpiBNx6gU/2fLWVmm7wQAAAABJRU5ErkJggg==';
 
-void main() {
-  runApp(const MyApp());
+void main() => run(Setup.canvasSaveLayer);
+
+enum Setup {
+  image,
+  canvasSaveLayer,
+}
+
+void run(Setup setup) {
+  runApp(MyApp(setup));
 }
 
 class MyApp extends StatelessWidget {
-  const MyApp({super.key});
+  const MyApp(this._setup, {super.key});
+
+  final Setup _setup;
 
   @override
   Widget build(BuildContext context) {
@@ -77,27 +87,101 @@ class MyApp extends StatelessWidget {
       theme: ThemeData(
         primarySwatch: Colors.blue,
       ),
-      home: const MyHomePage(title: 'Wide Gamut Test'),
+      home: MyHomePage(_setup, title: 'Wide Gamut Test'),
     );
   }
 }
 
-class MyHomePage extends StatelessWidget {
-  const MyHomePage({super.key, required this.title});
+class _SaveLayerDrawer extends CustomPainter {
+  _SaveLayerDrawer(this._image);
+
+  final ui.Image? _image;
+
+  @override
+  void paint(Canvas canvas, Size size) {
+    if (_image != null) {
+      final Rect imageRect = Rect.fromCenter(
+          center: Offset.zero,
+          width: _image!.width.toDouble(),
+          height: _image!.height.toDouble());
+      canvas.saveLayer(
+          imageRect,
+          Paint());
+      canvas.drawRect(
+          imageRect.inflate(-_image!.width.toDouble() / 4.0),
+          Paint()
+            ..style = PaintingStyle.stroke
+            ..color = const Color(0xffffffff)
+            ..strokeWidth = 3);
+      canvas.saveLayer(
+          imageRect,
+          Paint()..blendMode = BlendMode.multiply);
+      canvas.drawImage(_image!,
+          Offset(-_image!.width / 2.0, -_image!.height / 2.0), Paint());
+      canvas.restore();
+      canvas.restore();
+    }
+  }
+
+  @override
+  bool shouldRepaint(covariant CustomPainter oldDelegate) => true;
+}
+
+Future<ui.Image> _loadImage() async {
+  final ui.ImmutableBuffer buffer =
+      await ui.ImmutableBuffer.fromUint8List(base64Decode(_displayP3Logo));
+  final ui.ImageDescriptor descriptor =
+      await ui.ImageDescriptor.encoded(buffer);
+  final ui.Codec codec = await descriptor.instantiateCodec();
+  return (await codec.getNextFrame()).image;
+}
+
+class MyHomePage extends StatefulWidget {
+  const MyHomePage(this.setup, {super.key, required this.title});
 
+  final Setup setup;
   final String title;
 
+  @override
+  State<StatefulWidget> createState() => _MyHomePageState();
+}
+
+class _MyHomePageState extends State<MyHomePage> {
+  ui.Image? _image;
+
+  @override
+  void initState() {
+    if (widget.setup == Setup.canvasSaveLayer) {
+      _loadImage().then((ui.Image? value) {
+        setState(() {
+          _image = value;
+        });
+      });
+    }
+    super.initState();
+  }
+
   @override
   Widget build(BuildContext context) {
+    late Widget imageWidget;
+    switch (widget.setup) {
+      case Setup.image:
+        imageWidget = Image.memory(base64Decode(_displayP3Logo));
+        break;
+      case Setup.canvasSaveLayer:
+        imageWidget = CustomPaint(painter: _SaveLayerDrawer(_image));
+        break;
+    }
+
     return Scaffold(
       appBar: AppBar(
-        title: Text(title),
+        title: Text(widget.title),
       ),
       body: Center(
         child: Column(
           mainAxisAlignment: MainAxisAlignment.center,
           children: <Widget>[
-            Image.memory(base64Decode(_displayP3Logo)),
+            imageWidget,
           ],
         ),
       ),