Switch ui.window.devicePixelRatio from browser logical to physical.

.cirrus.yml

@@ -146,6 +146,7 @@ task:
         - $FRAMEWORK_PATH/flutter/bin/flutter config --local-engine=host_debug_unopt --no-analytics --enable-web
         - $FRAMEWORK_PATH/flutter/bin/flutter pub get --local-engine=host_debug_unopt
         - $FRAMEWORK_PATH/flutter/bin/flutter drive -v --target=test_driver/text_editing_e2e.dart -d web-server --release --browser-name=chrome --local-engine=host_debug_unopt
+        - $FRAMEWORK_PATH/flutter/bin/flutter drive -v --target=test_driver/image_loading_e2e.dart -d web-server --release --browser-name=chrome --local-engine=host_debug_unopt
 
     - name: build_and_test_web_linux_firefox
       compile_host_script: |

e2etests/web/regular_integration_tests/lib/image_loading_main.dart

@@ -0,0 +1,32 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
+
+void main() async {
+  const MethodChannel channel =
+  OptionalMethodChannel('flutter/web_test_e2e', JSONMethodCodec());
+  await channel.invokeMethod<void>(
+    'setDevicePixelRatio',
+    '1.5',
+  );
+  runApp(MyApp());
+}
+
+class MyApp extends StatefulWidget {
+  @override
+  MyAppState createState() => MyAppState();
+}
+
+class MyAppState extends State<MyApp> {
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+        key: const Key('mainapp'),
+        title: 'Integration Test App',
+        home: Image.asset('assets/images/sample_image1.png')
+    );
+  }
+}

e2etests/web/regular_integration_tests/pubspec.yaml

@@ -16,3 +16,7 @@ dev_dependencies:
   e2e: 0.2.4+4
   http: 0.12.0+2
   test: any
+
+flutter:
+  assets:
+    - assets/images/

e2etests/web/regular_integration_tests/test_driver/image_loading_e2e.dart

@@ -0,0 +1,25 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:html' as html;
+import 'package:flutter/widgets.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:regular_integration_tests/image_loading_main.dart' as app;
+
+import 'package:e2e/e2e.dart';
+
+void main() {
+  E2EWidgetsFlutterBinding.ensureInitialized() as E2EWidgetsFlutterBinding;
+
+  testWidgets('Image loads asset variant based on device pixel ratio',
+          (WidgetTester tester) async {
+    app.main();
+    await tester.pumpAndSettle();
+    final html.ImageElement imageElement = html.querySelector('img') as html.ImageElement;
+    expect(imageElement.naturalWidth, 1.5 * 100);
+    expect(imageElement.naturalHeight, 1.5 * 100);
+    expect(imageElement.width, 100);
+    expect(imageElement.height, 100);
+  });
+}

e2etests/web/regular_integration_tests/test_driver/image_loading_e2e_test.dart

@@ -0,0 +1,17 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:io';
+
+import 'package:flutter_driver/flutter_driver.dart';
+
+Future<void> main() async {
+  final FlutterDriver driver = await FlutterDriver.connect();
+
+  final String dataRequest =
+      await driver.requestData(null, timeout: const Duration(seconds: 1));
+  await driver.close();
+
+  exit(dataRequest == 'pass' ? 0 : 1);
+}

lib/web_ui/lib/src/engine/compositor/embedded_views.dart

@@ -69,9 +69,11 @@ class HtmlViewEmbedder {
     switch (decoded.method) {
       case 'create':
         _create(decoded, callback);
+        window._replyToPlatformMessage(callback, codec.encodeSuccessEnvelope(true));
         return;
       case 'dispose':
         _dispose(decoded, callback);
+        window._replyToPlatformMessage(callback, codec.encodeSuccessEnvelope(true));
         return;
     }
     callback(null);

lib/web_ui/lib/src/engine/dom_renderer.dart

@@ -419,12 +419,6 @@ flt-glass-pane * {
     // DOM tree.
     setElementAttribute(_sceneHostElement, 'aria-hidden', 'true');
 
-    // We treat browser pixels as device pixels because pointer events,
-    // position, and sizes all use browser pixel as the unit (i.e. "px" in CSS).
-    // Therefore, as far as the framework is concerned the device pixel ratio
-    // is 1.0.
-    window.debugOverrideDevicePixelRatio(1.0);
-
     if (html.window.visualViewport == null && isWebKit) {
       // Safari sometimes gives us bogus innerWidth/innerHeight values when the
       // page loads. When it changes the values to correct ones it does not

lib/web_ui/lib/src/engine/platform_views.dart

@@ -50,9 +50,11 @@ void handlePlatformViewCall(
   switch (decoded.method) {
     case 'create':
       _createPlatformView(decoded, callback);
+      window._replyToPlatformMessage(callback, codec.encodeSuccessEnvelope(true));
       return;
     case 'dispose':
       _disposePlatformView(decoded, callback);
+      window._replyToPlatformMessage(callback, codec.encodeSuccessEnvelope(true));
       return;
   }
   callback(null);

lib/web_ui/lib/src/engine/semantics/accessibility.dart

@@ -52,9 +52,9 @@ class AccessibilityAnnouncements {
   html.HtmlElement get _domElement => _element ??= _createElement();
 
   /// Decodes the message coming from the 'flutter/accessibility' channel.
-  void handleMessage(ByteData data) {
+  void handleMessage(StandardMessageCodec codec, ByteData data) {
     final Map<dynamic, dynamic> inputMap =
-        const StandardMessageCodec().decodeMessage(data);
+        codec.decodeMessage(data);
     final Map<dynamic, dynamic> dataMap = inputMap['data'];
     final String message = dataMap['message'];
     if (message != null && message.isNotEmpty) {

lib/web_ui/lib/src/engine/surface/scene_builder.dart

@@ -10,7 +10,8 @@ class SurfaceSceneBuilder implements ui.SceneBuilder {
     _surfaceStack.add(PersistedScene(_lastFrameScene));
   }
 
-  final List<PersistedContainerSurface> _surfaceStack = <PersistedContainerSurface>[];
+  final List<PersistedContainerSurface> _surfaceStack =
+      <PersistedContainerSurface>[];
 
   /// The scene built by this scene builder.
   ///
@@ -19,7 +20,8 @@ class SurfaceSceneBuilder implements ui.SceneBuilder {
     assert(() {
       if (_surfaceStack.length != 1) {
         final String surfacePrintout = _surfaceStack
-            .map<Type>((PersistedContainerSurface surface) => surface.runtimeType)
+            .map<Type>(
+                (PersistedContainerSurface surface) => surface.runtimeType)
             .toList()
             .join(', ');
         throw Exception('Incorrect sequence of push/pop operations while '
@@ -42,7 +44,8 @@ class SurfaceSceneBuilder implements ui.SceneBuilder {
     // the live tree.
     if (surface.oldLayer != null) {
       assert(surface.oldLayer.runtimeType == surface.runtimeType);
-      assert(debugAssertSurfaceState(surface.oldLayer, PersistedSurfaceState.active));
+      assert(debugAssertSurfaceState(
+          surface.oldLayer, PersistedSurfaceState.active));
       surface.oldLayer.state = PersistedSurfaceState.pendingUpdate;
     }
     _adoptSurface(surface);
@@ -97,6 +100,16 @@ class SurfaceSceneBuilder implements ui.SceneBuilder {
     if (matrix4.length != 16) {
       throw ArgumentError('"matrix4" must have 16 entries.');
     }
+    if (_surfaceStack.length == 1) {
+      // Top level transform contains view configuration to scale
+      // scene to devicepixelratio. Use identity instead since CSS uses
+      // logical device pixels.
+      if (!ui.debugEmulateFlutterTesterEnvironment) {
+        assert(matrix4[0] == window.devicePixelRatio &&
+           matrix4[5] == window.devicePixelRatio);
+      }
+      matrix4 = Matrix4.identity().storage;
+    }
     return _pushSurface(PersistedTransform(oldLayer, matrix4));
   }
 
@@ -276,7 +289,8 @@ class SurfaceSceneBuilder implements ui.SceneBuilder {
   void addRetained(ui.EngineLayer retainedLayer) {
     final PersistedContainerSurface retainedSurface = retainedLayer;
     if (assertionsEnabled) {
-      assert(debugAssertSurfaceState(retainedSurface, PersistedSurfaceState.active, PersistedSurfaceState.released));
+      assert(debugAssertSurfaceState(retainedSurface,
+          PersistedSurfaceState.active, PersistedSurfaceState.released));
     }
     retainedSurface.tryRetain();
     _adoptSurface(retainedSurface);
@@ -319,7 +333,8 @@ class SurfaceSceneBuilder implements ui.SceneBuilder {
   /// for more details.
   @override
   void addPerformanceOverlay(int enabledOptions, ui.Rect bounds) {
-    _addPerformanceOverlay(enabledOptions, bounds.left, bounds.right, bounds.top, bounds.bottom);
+    _addPerformanceOverlay(
+        enabledOptions, bounds.left, bounds.right, bounds.top, bounds.bottom);
   }
 
   /// Whether we've already warned the user about the lack of the performance
@@ -337,7 +352,8 @@ class SurfaceSceneBuilder implements ui.SceneBuilder {
   ) {
     if (!_webOnlyDidWarnAboutPerformanceOverlay) {
       _webOnlyDidWarnAboutPerformanceOverlay = true;
-      html.window.console.warn('The performance overlay isn\'t supported on the web');
+      html.window.console
+          .warn('The performance overlay isn\'t supported on the web');
     }
   }
 
@@ -377,7 +393,8 @@ class SurfaceSceneBuilder implements ui.SceneBuilder {
     _addTexture(offset.dx, offset.dy, width, height, textureId);
   }
 
-  void _addTexture(double dx, double dy, double width, double height, int textureId) {
+  void _addTexture(
+      double dx, double dy, double width, double height, int textureId) {
     // In test mode, allow this to be a no-op.
     if (!ui.debugEmulateFlutterTesterEnvironment) {
       throw UnimplementedError('Textures are not supported in Flutter Web');

lib/web_ui/lib/src/engine/text_editing/text_editing.dart

@@ -778,8 +778,11 @@ class TextEditingChannel {
   final HybridTextEditing implementation;
 
   /// Handles "flutter/textinput" platform messages received from the framework.
-  void handleTextInput(ByteData data) {
-    final MethodCall call = const JSONMethodCodec().decodeMethodCall(data);
+  void handleTextInput(
+      ByteData data,
+      ui.PlatformMessageResponseCallback callback) {
+    const JSONMethodCodec codec = JSONMethodCodec();
+    final MethodCall call = codec.decodeMethodCall(data);
     switch (call.method) {
       case 'TextInput.setClient':
         implementation.setClient(
@@ -815,6 +818,7 @@ class TextEditingChannel {
       default:
         throw StateError('Unsupported method call on the flutter/textinput channel: ${call.method}');
     }
+    window._replyToPlatformMessage(callback, codec.encodeSuccessEnvelope(true));
   }
 
   /// Sends the 'TextInputClient.updateEditingState' message to the framework.

lib/web_ui/lib/src/engine/window.dart

@@ -15,19 +15,11 @@ class EngineWindow extends ui.Window {
   }
 
   @override
-  double get devicePixelRatio {
-    if (_debugDevicePixelRatio != null) {
-      return _debugDevicePixelRatio;
-    }
+  double get devicePixelRatio => _debugDevicePixelRatio != null
+      ? _debugDevicePixelRatio
+      : browserDevicePixelRatio;
 
-    if (experimentalUseSkia) {
-      return browserDevicePixelRatio;
-    } else {
-      return 1.0;
-    }
-  }
-
-  /// Returns device pixel ratio returns by browser.
+  /// Returns device pixel ratio returned by browser.
   static double get browserDevicePixelRatio {
     double ratio = html.window.devicePixelRatio;
     // Guard against WebOS returning 0.
@@ -38,10 +30,7 @@ class EngineWindow extends ui.Window {
   ///
   /// This is useful in tests to emulate screens of different dimensions.
   void debugOverrideDevicePixelRatio(double value) {
-    assert(() {
-      _debugDevicePixelRatio = value;
-      return true;
-    }());
+    _debugDevicePixelRatio = value;
   }
 
   double _debugDevicePixelRatio;
@@ -160,26 +149,38 @@ class EngineWindow extends ui.Window {
           case 'HapticFeedback.vibrate':
             final String type = decoded.arguments;
             domRenderer.vibrate(_getHapticFeedbackDuration(type));
+            _replyToPlatformMessage(callback, codec.encodeSuccessEnvelope(true));
             return;
           case 'SystemChrome.setApplicationSwitcherDescription':
             final Map<String, dynamic> arguments = decoded.arguments;
             domRenderer.setTitle(arguments['label']);
             domRenderer.setThemeColor(ui.Color(arguments['primaryColor']));
+            _replyToPlatformMessage(callback, codec.encodeSuccessEnvelope(true));
             return;
           case 'SystemSound.play':
             // There are no default system sounds on web.
+            _replyToPlatformMessage(callback, codec.encodeSuccessEnvelope(true));
             return;
           case 'Clipboard.setData':
             ClipboardMessageHandler().setDataMethodCall(decoded, callback);
+            _replyToPlatformMessage(callback, codec.encodeSuccessEnvelope(true));
             return;
           case 'Clipboard.getData':
             ClipboardMessageHandler().getDataMethodCall(callback);
+            _replyToPlatformMessage(callback, codec.encodeSuccessEnvelope(true));
             return;
         }
         break;
 
       case 'flutter/textinput':
-        textEditing.channel.handleTextInput(data);
+        textEditing.channel.handleTextInput(data, callback);
+        return;
+
+      case 'flutter/web_test_e2e':
+        const MethodCodec codec = JSONMethodCodec();
+        _replyToPlatformMessage(callback, codec.encodeSuccessEnvelope(
+          _handleWebTestEnd2EndMessage(codec, data)
+        ));
         return;
 
       case 'flutter/platform_views':
@@ -192,7 +193,9 @@ class EngineWindow extends ui.Window {
 
       case 'flutter/accessibility':
         // In widget tests we want to bypass processing of platform messages.
-        accessibilityAnnouncements.handleMessage(data);
+        final StandardMessageCodec codec = StandardMessageCodec();
+        accessibilityAnnouncements.handleMessage(codec, data);
+        _replyToPlatformMessage(callback, codec.encodeMessage(true));
         return;
 
       case 'flutter/navigation':
@@ -204,9 +207,11 @@ class EngineWindow extends ui.Window {
           case 'routePushed':
           case 'routeReplaced':
             _browserHistory.setRouteName(message['routeName']);
+            _replyToPlatformMessage(callback, codec.encodeSuccessEnvelope(true));
             break;
           case 'routePopped':
             _browserHistory.setRouteName(message['previousRouteName']);
+            _replyToPlatformMessage(callback, codec.encodeSuccessEnvelope(true));
             break;
         }
         return;
@@ -250,7 +255,9 @@ class EngineWindow extends ui.Window {
     ByteData data,
   ) {
     Future<void>.delayed(Duration.zero).then((_) {
-      callback(data);
+      if (callback != null) {
+        callback(data);
+      }
     });
   }
 
@@ -315,6 +322,20 @@ class EngineWindow extends ui.Window {
   Rasterizer rasterizer = experimentalUseSkia ? Rasterizer(Surface()) : null;
 }
 
+bool _handleWebTestEnd2EndMessage(MethodCodec codec, ByteData data) {
+  final MethodCall decoded = codec.decodeMethodCall(data);
+  final Map<String, dynamic> message = decoded.arguments;
+  double ratio = double.parse(decoded.arguments);
+  bool result = false;
+  switch(decoded.method) {
+    case 'setDevicePixelRatio':
+      window.debugOverrideDevicePixelRatio(ratio);
+      window.onMetricsChanged();
+      return true;
+  }
+  return false;
+}
+
 /// The window singleton.
 ///
 /// `dart:ui` window delegates to this value. However, this value has a wider

lib/web_ui/lib/src/ui/test_embedding.dart

@@ -29,7 +29,7 @@ Future<dynamic> ensureTestPlatformInitializedThenRunTest(
 /// are available.
 Future<void> _platformInitializedFuture;
 
-/// Initializes domRenderer with specific devicePixelRation and physicalSize.
+/// Initializes domRenderer with specific devicePixelRatio and physicalSize.
 Future<void> webOnlyInitializeTestDomRenderer({double devicePixelRatio = 3.0}) {
   // Force-initialize DomRenderer so it doesn't overwrite test pixel ratio.
   engine.domRenderer;