Add a layoutDirection parameter to AndroidView (flutter#20838)

engine-flutter-autoroll · Aug 23, 2018 · 1fc7814 · 1fc7814
1 parent 5d1f874
commit 1fc7814
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Showing 5 changed files with 281 additions and 48 deletions.
diff --git a/packages/flutter/lib/src/services/platform_views.dart b/packages/flutter/lib/src/services/platform_views.dart
@@ -59,16 +59,21 @@ class PlatformViewsService {
   ///
   /// The Android view will only be created after [AndroidViewController.setSize] is called for the
   /// first time.
+  ///
+  /// The `id, `viewType, and `layoutDirection` parameters must not be null.
   static AndroidViewController initAndroidView({
     @required int id,
     @required String viewType,
+    @required TextDirection layoutDirection,
     PlatformViewCreatedCallback onPlatformViewCreated,
   }) {
     assert(id != null);
     assert(viewType != null);
+    assert(layoutDirection != null);
     return new AndroidViewController._(
         id,
         viewType,
+        layoutDirection,
         onPlatformViewCreated
     );
   }
@@ -343,10 +348,13 @@ class AndroidViewController {
   AndroidViewController._(
     this.id,
     String viewType,
+    TextDirection layoutDirection,
     PlatformViewCreatedCallback onPlatformViewCreated,
   ) : assert(id != null),
       assert(viewType != null),
+      assert(layoutDirection != null),
       _viewType = viewType,
+      _layoutDirection = layoutDirection,
       _onPlatformViewCreated = onPlatformViewCreated,
       _state = _AndroidViewState.waitingForSize;
 
@@ -380,6 +388,12 @@ class AndroidViewController {
   /// Android's [MotionEvent.ACTION_POINTER_UP](https://developer.android.com/reference/android/view/MotionEvent#ACTION_POINTER_UP)
   static const int kActionPointerUp =  6;
 
+  /// Android's [View.LAYOUT_DIRECTION_LTR](https://developer.android.com/reference/android/view/View.html#LAYOUT_DIRECTION_LTR) value.
+  static const int kAndroidLayoutDirectionLtr = 0;
+
+  /// Android's [View.LAYOUT_DIRECTION_RTL](https://developer.android.com/reference/android/view/View.html#LAYOUT_DIRECTION_RTL) value.
+  static const int kAndroidLayoutDirectionRtl = 1;
+
   /// The unique identifier of the Android view controlled by this controller.
   final int id;
 
@@ -396,6 +410,8 @@ class AndroidViewController {
   /// disposed.
   int get textureId => _textureId;
 
+  TextDirection _layoutDirection;
+
   _AndroidViewState _state;
 
   /// Disposes the Android view.
@@ -430,6 +446,37 @@ class AndroidViewController {
     });
   }
 
+  /// Sets the layout direction for the Android view.
+  Future<void> setLayoutDirection(TextDirection layoutDirection) async {
+    if (_state == _AndroidViewState.disposed)
+      throw new FlutterError('trying to set a layout direction for a disposed Android View. View id: $id');
+
+    if (layoutDirection == _layoutDirection)
+      return;
+
+    assert(layoutDirection != null);
+    _layoutDirection = layoutDirection;
+
+    // If the view was not yet created we just update _layoutDirection and return, as the new
+    // direction will be used in _create.
+    if (_state == _AndroidViewState.waitingForSize)
+      return;
+
+    await SystemChannels.platform_views.invokeMethod('setDirection', <String, dynamic> {
+      'id': id,
+      'direction': _getAndroidDirection(layoutDirection),
+    });
+  }
+
+  static int _getAndroidDirection(TextDirection direction) {
+    switch (direction) {
+      case TextDirection.ltr:
+        return kAndroidLayoutDirectionLtr;
+      case TextDirection.rtl:
+        return kAndroidLayoutDirectionRtl;
+    }
+  }
+
   /// Sends an Android [MotionEvent](https://developer.android.com/reference/android/view/MotionEvent)
   /// to the view.
   ///
@@ -454,6 +501,7 @@ class AndroidViewController {
       'viewType': _viewType,
       'width': size.width,
       'height': size.height,
+      'direction': _getAndroidDirection(_layoutDirection),
     });
     if (_onPlatformViewCreated != null)
       _onPlatformViewCreated(id);

diff --git a/packages/flutter/lib/src/widgets/platform_view.dart b/packages/flutter/lib/src/widgets/platform_view.dart
@@ -6,6 +6,8 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/services.dart';
 
+import 'basic.dart';
+import 'debug.dart';
 import 'framework.dart';
 
 /// Embeds an Android view in the Widget hierarchy.
@@ -45,6 +47,7 @@ class AndroidView extends StatefulWidget {
     @required this.viewType,
     this.onPlatformViewCreated,
     this.hitTestBehavior = PlatformViewHitTestBehavior.opaque,
+    this.layoutDirection,
   }) : assert(viewType != null),
        assert(hitTestBehavior != null),
        super(key: key);
@@ -66,13 +69,20 @@ class AndroidView extends StatefulWidget {
   /// This defaults to [PlatformViewHitTestBehavior.opaque].
   final PlatformViewHitTestBehavior hitTestBehavior;
 
+  /// The text direction to use for the embedded view.
+  ///
+  /// If this is null, the ambient [Directionality] is used instead.
+  final TextDirection layoutDirection;
+
   @override
   State createState() => new _AndroidViewState();
 }
 
 class _AndroidViewState extends State<AndroidView> {
   int _id;
   AndroidViewController _controller;
+  TextDirection _layoutDirection;
+  bool _initialized = false;
 
   @override
   Widget build(BuildContext context) {
@@ -82,19 +92,53 @@ class _AndroidViewState extends State<AndroidView> {
     );
   }
 
-  @override
-  void initState() {
-    super.initState();
+  void _initializeOnce() {
+    if (_initialized) {
+      return;
+    }
+    _initialized = true;
+    _layoutDirection = _findLayoutDirection();
     _createNewAndroidView();
   }
 
+  @override
+  void didChangeDependencies() {
+    super.didChangeDependencies();
+    _initializeOnce();
+
+    final TextDirection newLayoutDirection = _findLayoutDirection();
+    final bool didChangeLayoutDirection = _layoutDirection != newLayoutDirection;
+    _layoutDirection = newLayoutDirection;
+
+    if (didChangeLayoutDirection) {
+      // The native view will update asynchronously, in the meantime we don't want
+      // to block the framework. (so this is intentionally not awaiting).
+      _controller.setLayoutDirection(_layoutDirection);
+    }
+  }
+
   @override
   void didUpdateWidget(AndroidView oldWidget) {
     super.didUpdateWidget(oldWidget);
-    if (widget.viewType == oldWidget.viewType)
+
+    final TextDirection newLayoutDirection = _findLayoutDirection();
+    final bool didChangeLayoutDirection = _layoutDirection != newLayoutDirection;
+    _layoutDirection = newLayoutDirection;
+
+    if (widget.viewType != oldWidget.viewType) {
+      _controller.dispose();
+      _createNewAndroidView();
       return;
-    _controller.dispose();
-    _createNewAndroidView();
+    }
+
+    if (didChangeLayoutDirection) {
+      _controller.setLayoutDirection(_layoutDirection);
+    }
+  }
+
+  TextDirection _findLayoutDirection() {
+    assert(widget.layoutDirection != null || debugCheckHasDirectionality(context));
+    return widget.layoutDirection ?? Directionality.of(context);
   }
 
   @override
@@ -108,10 +152,10 @@ class _AndroidViewState extends State<AndroidView> {
     _controller = PlatformViewsService.initAndroidView(
         id: _id,
         viewType: widget.viewType,
+        layoutDirection: _layoutDirection,
         onPlatformViewCreated: widget.onPlatformViewCreated
     );
   }
-
 }
 
 class _AndroidPlatformView extends LeafRenderObjectWidget {

diff --git a/packages/flutter/test/services/fake_platform_views.dart b/packages/flutter/test/services/fake_platform_views.dart
@@ -47,6 +47,8 @@ class FakePlatformViewsController {
         return _resize(call);
       case 'touch':
         return _touch(call);
+      case 'setDirection':
+        return _setDirection(call);
     }
     return new Future<Null>.sync(() => null);
   }
@@ -57,6 +59,7 @@ class FakePlatformViewsController {
     final String viewType = args['viewType'];
     final double width = args['width'];
     final double height = args['height'];
+    final int layoutDirection = args['direction'];
 
     if (_views.containsKey(id))
       throw new PlatformException(
@@ -70,7 +73,7 @@ class FakePlatformViewsController {
         message: 'Trying to create a platform view of unregistered type: $viewType',
       );
 
-    _views[id] = new FakePlatformView(id, viewType, new Size(width, height));
+    _views[id] = new FakePlatformView(id, viewType, new Size(width, height), layoutDirection);
     final int textureId = _textureCounter++;
     return new Future<int>.sync(() => textureId);
   }
@@ -130,15 +133,31 @@ class FakePlatformViewsController {
     return new Future<Null>.sync(() => null);
   }
 
+  Future<dynamic> _setDirection(MethodCall call) async {
+    final Map<dynamic, dynamic> args = call.arguments;
+    final int id = args['id'];
+    final int layoutDirection = args['direction'];
+
+    if (!_views.containsKey(id))
+      throw new PlatformException(
+        code: 'error',
+        message: 'Trying to resize a platform view with unknown id: $id',
+      );
+
+    _views[id].layoutDirection = layoutDirection;
+
+    return new Future<Null>.sync(() => null);
+  }
 }
 
 class FakePlatformView {
 
-  FakePlatformView(this.id, this.type, this.size);
+  FakePlatformView(this.id, this.type, this.size, this.layoutDirection);
 
   final int id;
   final String type;
   Size size;
+  int layoutDirection;
 
   @override
   bool operator ==(dynamic other) {
@@ -151,11 +170,11 @@ class FakePlatformView {
   }
 
   @override
-  int get hashCode => hashValues(id, type, size);
+  int get hashCode => hashValues(id, type, size, layoutDirection);
 
   @override
   String toString() {
-    return 'FakePlatformView(id: $id, type: $type, size: $size)';
+    return 'FakePlatformView(id: $id, type: $type, size: $size, layoutDirection: $layoutDirection)';
   }
 }