Fix AndroidView offset and resize (#99888)

packages/flutter/lib/src/rendering/platform_view.dart

@@ -6,6 +6,7 @@ import 'dart:ui';
 
 import 'package:flutter/foundation.dart';
 import 'package:flutter/gestures.dart';
+import 'package:flutter/scheduler.dart';
 import 'package:flutter/semantics.dart';
 import 'package:flutter/services.dart';
 
@@ -90,10 +91,15 @@ class RenderAndroidView extends RenderBox with _PlatformViewGestureMixin {
     updateGestureRecognizers(gestureRecognizers);
     _viewController.addOnPlatformViewCreatedListener(_onPlatformViewCreated);
     this.hitTestBehavior = hitTestBehavior;
+    _setOffset();
   }
 
   _PlatformViewState _state = _PlatformViewState.uninitialized;
 
+  Size? _currentTextureSize;
+
+  bool _isDisposed = false;
+
   /// The Android view controller for the Android view associated with this render object.
   AndroidViewController get viewController => _viewController;
   AndroidViewController _viewController;
@@ -172,8 +178,6 @@ class RenderAndroidView extends RenderBox with _PlatformViewGestureMixin {
     _sizePlatformView();
   }
 
-  late Size _currentAndroidViewSize;
-
   Future<void> _sizePlatformView() async {
     // Android virtual displays cannot have a zero size.
     // Trying to size it to 0 crashes the app, which was happening when starting the app
@@ -188,8 +192,7 @@ class RenderAndroidView extends RenderBox with _PlatformViewGestureMixin {
     Size targetSize;
     do {
       targetSize = size;
-      await _viewController.setSize(targetSize);
-      _currentAndroidViewSize = targetSize;
+      _currentTextureSize = await _viewController.setSize(targetSize);
       // We've resized the platform view to targetSize, but it is possible that
       // while we were resizing the render object's size was changed again.
       // In that case we will resize the platform view again.
@@ -199,14 +202,39 @@ class RenderAndroidView extends RenderBox with _PlatformViewGestureMixin {
     markNeedsPaint();
   }
 
+  // Sets the offset of the underlaying platform view on the platform side.
+  //
+  // This allows the Android native view to draw the a11y highlights in the same
+  // location on the screen as the platform view widget in the Flutter framework.
+  //
+  // It also allows platform code to obtain the correct position of the Android
+  // native view on the screen.
+  void _setOffset() {
+    SchedulerBinding.instance.addPostFrameCallback((_) async {
+      if (!_isDisposed) {
+        await _viewController.setOffset(localToGlobal(Offset.zero));
+        // Schedule a new post frame callback.
+        _setOffset();
+      }
+    });
+  }
+
   @override
   void paint(PaintingContext context, Offset offset) {
     if (_viewController.textureId == null)
       return;
 
-    // Clip the texture if it's going to paint out of the bounds of the renter box
-    // (see comment in _paintTexture for an explanation of when this happens).
-    if ((size.width < _currentAndroidViewSize.width || size.height < _currentAndroidViewSize.height) && clipBehavior != Clip.none) {
+    // As resizing the Android view happens asynchronously we don't know exactly when is a
+    // texture frame with the new size is ready for consumption.
+    // TextureLayer is unaware of the texture frame's size and always maps it to the
+    // specified rect. If the rect we provide has a different size from the current texture frame's
+    // size the texture frame will be scaled.
+    // To prevent unwanted scaling artifacts while resizing, clip the texture.
+    // This guarantees that the size of the texture frame we're painting is always
+    // _currentAndroidTextureSize.
+    final bool isTextureLargerThanWidget = _currentTextureSize!.width > size.width ||
+                                           _currentTextureSize!.height > size.height;
+    if (isTextureLargerThanWidget && clipBehavior != Clip.none) {
       _clipRectLayer.layer = context.pushClipRect(
         true,
         offset,
@@ -225,24 +253,18 @@ class RenderAndroidView extends RenderBox with _PlatformViewGestureMixin {
 
   @override
   void dispose() {
+    _isDisposed = true;
     _clipRectLayer.layer = null;
     super.dispose();
   }
 
   void _paintTexture(PaintingContext context, Offset offset) {
-    // As resizing the Android view happens asynchronously we don't know exactly when is a
-    // texture frame with the new size is ready for consumption.
-    // TextureLayer is unaware of the texture frame's size and always maps it to the
-    // specified rect. If the rect we provide has a different size from the current texture frame's
-    // size the texture frame will be scaled.
-    // To prevent unwanted scaling artifacts while resizing we freeze the texture frame, until
-    // we know that a frame with the new size is in the buffer.
-    // This guarantees that the size of the texture frame we're painting is always
-    // _currentAndroidViewSize.
+    if (_currentTextureSize == null)
+      return;
+
     context.addLayer(TextureLayer(
-      rect: offset & _currentAndroidViewSize,
-      textureId: _viewController.textureId!,
-      freeze: _state == _PlatformViewState.resizing,
+      rect: offset & _currentTextureSize!,
+      textureId: viewController.textureId!,
     ));
   }
 

packages/flutter/lib/src/services/platform_views.dart

@@ -780,11 +780,27 @@ abstract class AndroidViewController extends PlatformViewController {
 
   /// Sizes the Android View.
   ///
-  /// `size` is the view's new size in logical pixel, it must not be null and must
+  /// [size] is the view's new size in logical pixel, it must not be null and must
   /// be bigger than zero.
   ///
   /// The first time a size is set triggers the creation of the Android view.
-  Future<void> setSize(Size size);
+  ///
+  /// Returns the buffer size in logical pixel that backs the texture where the platform
+  /// view pixels are written to.
+  ///
+  /// The buffer size may or may not be the same as [size].
+  ///
+  /// As a result, consumers are expected to clip the texture using [size], while using
+  /// the return value to size the texture.
+  Future<Size> setSize(Size size);
+
+  /// Sets the offset of the platform view.
+  ///
+  /// [off] is the view's new offset in logical pixel.
+  ///
+  /// On Android, this allows the Android native view to draw the a11y highlights in the same
+  /// location on the screen as the platform view widget in the Flutter framework.
+  Future<void> setOffset(Offset off);
 
   /// Returns the texture entry id that the Android view is rendering into.
   ///
@@ -975,15 +991,19 @@ class SurfaceAndroidViewController extends AndroidViewController {
   }
 
   @override
-  Future<void> setSize(Size size) {
+  Future<Size> setSize(Size size) {
+    throw UnimplementedError('Not supported for $SurfaceAndroidViewController.');
+  }
+
+  @override
+  Future<void> setOffset(Offset off) {
     throw UnimplementedError('Not supported for $SurfaceAndroidViewController.');
   }
 }
 
 /// Controls an Android view that is rendered to a texture.
 ///
-/// This is typically used by [AndroidView] to display an Android View in a
-/// [VirtualDisplay](https://developer.android.com/reference/android/hardware/display/VirtualDisplay).
+/// This is typically used by [AndroidView] to display an Android View in the Android view hierarchy.
 ///
 /// Typically created with [PlatformViewsService.initAndroidView].
 class TextureAndroidViewController extends AndroidViewController {
@@ -1012,25 +1032,59 @@ class TextureAndroidViewController extends AndroidViewController {
   @override
   int? get textureId => _textureId;
 
-  late Size _size;
+  late Size _initialSize;
+
+  /// The current offset of the platform view.
+  Offset _off = Offset.zero;
 
   @override
-  Future<void> setSize(Size size) async {
+  Future<Size> setSize(Size size) async {
     assert(_state != _AndroidViewState.disposed, 'trying to size a disposed Android View. View id: $viewId');
 
     assert(size != null);
     assert(!size.isEmpty);
 
     if (_state == _AndroidViewState.waitingForSize) {
-      _size = size;
-      return create();
+      _initialSize = size;
+      await create();
+      return _initialSize;
     }
 
-    await SystemChannels.platform_views.invokeMethod<void>('resize', <String, dynamic>{
+    final Map<Object?, Object?>? meta = await SystemChannels.platform_views.invokeMapMethod<Object?, Object?>(
+      'resize',
+      <String, dynamic>{
         'id': viewId,
         'width': size.width,
         'height': size.height,
-    });
+      },
+    );
+    assert(meta != null);
+    assert(meta!.containsKey('width'));
+    assert(meta!.containsKey('height'));
+    return Size(meta!['width']! as double, meta['height']! as double);
+  }
+
+  @override
+  Future<void> setOffset(Offset off) async {
+    if (off == _off)
+      return;
+
+    // Don't set the offset unless the Android view has been created.
+    // The implementation of this method channel throws if the Android view for this viewId
+    // isn't addressable.
+    if (_state != _AndroidViewState.created)
+      return;
+
+    _off = off;
+
+    await SystemChannels.platform_views.invokeMethod<void>(
+      'offset',
+      <String, dynamic>{
+        'id': viewId,
+        'top': off.dy,
+        'left': off.dx,
+      },
+    );
   }
 
   /// Creates the Android View.
@@ -1043,13 +1097,13 @@ class TextureAndroidViewController extends AndroidViewController {
 
   @override
   Future<void> _sendCreateMessage() async {
-    assert(!_size.isEmpty, 'trying to create $TextureAndroidViewController without setting a valid size.');
+    assert(!_initialSize.isEmpty, 'trying to create $TextureAndroidViewController without setting a valid size.');
 
     final Map<String, dynamic> args = <String, dynamic>{
       'id': viewId,
       'viewType': _viewType,
-      'width': _size.width,
-      'height': _size.height,
+      'width': _initialSize.width,
+      'height': _initialSize.height,
       'direction': AndroidViewController._getAndroidDirection(_layoutDirection),
     };
     if (_creationParams != null) {

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

@@ -546,7 +546,7 @@ class _AndroidViewState extends State<AndroidView> {
     }
     SystemChannels.textInput.invokeMethod<void>(
       'TextInput.setPlatformViewClient',
-      <String, dynamic>{'platformViewId': _id, 'usesVirtualDisplay': true},
+      <String, dynamic>{'platformViewId': _id},
     ).catchError((dynamic e) {
       if (e is MissingPluginException) {
         // We land the framework part of Android platform views keyboard

packages/flutter/test/services/fake_platform_views.dart

@@ -83,7 +83,12 @@ class FakeAndroidViewController implements AndroidViewController {
   }
 
   @override
-  Future<void> setSize(Size size) {
+  Future<Size> setSize(Size size) {
+    throw UnimplementedError();
+  }
+
+  @override
+  Future<void> setOffset(Offset off) {
     throw UnimplementedError();
   }
 
@@ -140,6 +145,8 @@ class FakeAndroidPlatformViewsController {
 
   bool synchronizeToNativeViewHierarchy = true;
 
+  Map<int, Offset> offsets = <int, Offset>{};
+
   void registerViewType(String viewType) {
     _registeredViewTypes.add(viewType);
   }
@@ -165,6 +172,8 @@ class FakeAndroidPlatformViewsController {
         return _setDirection(call);
       case 'clearFocus':
         return _clearFocus(call);
+      case 'offset':
+        return _offset(call);
       case 'synchronizeToNativeViewHierarchy':
         return _synchronizeToNativeViewHierarchy(call);
     }
@@ -247,6 +256,15 @@ class FakeAndroidPlatformViewsController {
     }
     _views[id] = _views[id]!.copyWith(size: Size(width, height));
 
+    return Future<Map<dynamic, dynamic>>.sync(() => <dynamic, dynamic>{'width': width, 'height': height});
+  }
+
+  Future<dynamic> _offset(MethodCall call) async {
+    final Map<dynamic, dynamic> args = call.arguments as Map<dynamic, dynamic>;
+    final int id = args['id'] as int;
+    final double top = args['top'] as double;
+    final double left = args['left'] as double;
+    offsets[id] = Offset(left, top);
     return Future<dynamic>.sync(() => null);
   }
 

packages/flutter/test/services/platform_views_test.dart

@@ -219,6 +219,28 @@ void main() {
       );
     });
 
+    test("set Android view's offset if view is created", () async {
+      viewsController.registerViewType('webview');
+      final AndroidViewController viewController =
+      PlatformViewsService.initAndroidView(id: 7, viewType: 'webview', layoutDirection: TextDirection.ltr);
+      await viewController.setSize(const Size(100.0, 100.0)); // Creates view.
+      await viewController.setOffset(const Offset(10, 20));
+      expect(
+        viewsController.offsets,
+        equals(<int, Offset>{
+          7: const Offset(10, 20),
+        }),
+      );
+    });
+
+    test("doesn't set Android view's offset if view isn't created", () async {
+      viewsController.registerViewType('webview');
+      final AndroidViewController viewController =
+      PlatformViewsService.initAndroidView(id: 7, viewType: 'webview', layoutDirection: TextDirection.ltr);
+      await viewController.setOffset(const Offset(10, 20));
+      expect(viewsController.offsets, equals(<int, Offset>{}));
+    });
+
     test('synchronizeToNativeViewHierarchy', () async {
       await PlatformViewsService.synchronizeToNativeViewHierarchy(false);
       expect(viewsController.synchronizeToNativeViewHierarchy, false);

packages/flutter/test/widgets/platform_view_test.dart

@@ -1087,9 +1087,6 @@ void main() {
 
       expect(lastPlatformViewTextClient.containsKey('platformViewId'), true);
       expect(lastPlatformViewTextClient['platformViewId'], currentViewId + 1);
-
-      expect(lastPlatformViewTextClient.containsKey('usesVirtualDisplay'), true);
-      expect(lastPlatformViewTextClient['usesVirtualDisplay'], true);
     });
 
     testWidgets('AndroidView clears platform focus when unfocused', (WidgetTester tester) async {
@@ -1224,6 +1221,24 @@ void main() {
       clipRectLayer = tester.layers.whereType<ClipRectLayer>().first;
       expect(clipRectLayer.clipRect, const Rect.fromLTWH(0.0, 0.0, 50.0, 50.0));
     });
+
+    testWidgets('offset is sent to the platform', (WidgetTester tester) async {
+      final FakeAndroidPlatformViewsController viewsController = FakeAndroidPlatformViewsController();
+      viewsController.registerViewType('webview');
+
+      await tester.pumpWidget(
+        const Padding(
+          padding: EdgeInsets.fromLTRB(10, 20, 0, 0),
+          child: AndroidView(
+            viewType: 'webview',
+            layoutDirection: TextDirection.ltr,
+          ),
+        ),
+      );
+
+      await tester.pump();
+      expect(viewsController.offsets.values, equals(<Offset>[const Offset(10, 20)]));
+    });
   });
 
   group('AndroidViewSurface', () {
@@ -2615,8 +2630,6 @@ void main() {
       expect(focusNode.hasFocus, true);
       expect(lastPlatformViewTextClient.containsKey('platformViewId'), true);
       expect(lastPlatformViewTextClient['platformViewId'], viewId);
-
-      expect(lastPlatformViewTextClient.containsKey('usesVirtualDisplay'), false);
     });
   });