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0fb84e96c7
* Future<void> main * Future<void>.delayed * prefer_void_to_Null * address review comments
466 lines
16 KiB
Dart
466 lines
16 KiB
Dart
// Copyright 2018 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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import 'dart:async';
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import 'dart:ui';
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import 'package:flutter/foundation.dart';
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import 'package:flutter/gestures.dart';
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import 'package:flutter/services.dart';
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import 'box.dart';
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import 'layer.dart';
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import 'object.dart';
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/// How an embedded platform view behave during hit tests.
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enum PlatformViewHitTestBehavior {
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/// Opaque targets can be hit by hit tests, causing them to both receive
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/// events within their bounds and prevent targets visually behind them from
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/// also receiving events.
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opaque,
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/// Translucent targets both receive events within their bounds and permit
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/// targets visually behind them to also receive events.
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translucent,
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/// Transparent targets don't receive events within their bounds and permit
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/// targets visually behind them to receive events.
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transparent,
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}
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enum _PlatformViewState {
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uninitialized,
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resizing,
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ready,
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}
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/// A render object for an Android view.
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///
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/// Requires Android API level 20 or greater.
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///
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/// [RenderAndroidView] is responsible for sizing, displaying and passing touch events to an
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/// Android [View](https://developer.android.com/reference/android/view/View).
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///
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/// The render object's layout behavior is to fill all available space, the parent of this object must
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/// provide bounded layout constraints.
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///
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/// RenderAndroidView participates in Flutter's [GestureArena]s, and dispatches touch events to the
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/// Android view iff it won the arena. Specific gestures that should be dispatched to the Android
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/// view can be specified with factories in [RenderAndroidView.gestureRecognizers]. If
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/// [RenderAndroidView.gestureRecognizers] is empty, the gesture will be dispatched to the Android
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/// view iff it was not claimed by any other gesture recognizer.
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///
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/// See also:
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/// * [AndroidView] which is a widget that is used to show an Android view.
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/// * [PlatformViewsService] which is a service for controlling platform views.
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class RenderAndroidView extends RenderBox {
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/// Creates a render object for an Android view.
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RenderAndroidView({
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@required AndroidViewController viewController,
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@required this.hitTestBehavior,
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@required Set<Factory<OneSequenceGestureRecognizer>> gestureRecognizers,
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}) : assert(viewController != null),
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assert(hitTestBehavior != null),
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assert(gestureRecognizers != null),
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_viewController = viewController
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{
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_motionEventsDispatcher = _MotionEventsDispatcher(globalToLocal, viewController);
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updateGestureRecognizers(gestureRecognizers);
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}
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_PlatformViewState _state = _PlatformViewState.uninitialized;
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/// The Android view controller for the Android view associated with this render object.
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AndroidViewController get viewcontroller => _viewController;
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AndroidViewController _viewController;
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/// Sets a new Android view controller.
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///
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/// `viewController` must not be null.
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set viewController(AndroidViewController viewController) {
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assert(_viewController != null);
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if (_viewController == viewController)
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return;
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_viewController = viewController;
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_sizePlatformView();
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}
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/// How to behave during hit testing.
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// The implicit setter is enough here as changing this value will just affect
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// any newly arriving events there's nothing we need to invalidate.
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PlatformViewHitTestBehavior hitTestBehavior;
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/// Which gestures should be forwarded to the Android view.
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///
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/// Gesture recognizers created by factories in this set participate in the gesture arena for each
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/// pointer that was put down on the render box. If any of the recognizers on this list wins the
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/// gesture arena, the entire pointer event sequence starting from the pointer down event
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/// will be dispatched to the Android view.
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///
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/// The `gestureRecognizers` property must not contain more than one factory with the same [Factory.type].
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///
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/// Setting a new set of gesture recognizer factories with the same [Factory.type]s as the current
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/// set has no effect, because the factories' constructors would have already been called with the previous set.
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///
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/// Any active gesture arena the Android view participates in is rejected when the
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/// set of gesture recognizers is changed.
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void updateGestureRecognizers(Set<Factory<OneSequenceGestureRecognizer>> gestureRecognizers) {
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assert(gestureRecognizers != null);
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assert(_factoriesTypeSet(gestureRecognizers).length == gestureRecognizers.length);
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if (_factoryTypesSetEquals(gestureRecognizers, _gestureRecognizer?.gestureRecognizerFactories)) {
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return;
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}
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_gestureRecognizer?.dispose();
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_gestureRecognizer = _AndroidViewGestureRecognizer(_motionEventsDispatcher, gestureRecognizers);
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}
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static bool _factoryTypesSetEquals<T>(Set<Factory<T>> a, Set<Factory<T>> b) {
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if (a == b) {
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return true;
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}
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if (a == null || b == null) {
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return false;
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}
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return setEquals(_factoriesTypeSet(a), _factoriesTypeSet(b));
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}
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static Set<Type> _factoriesTypeSet<T>(Set<Factory<T>> factories) {
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return factories.map<Type>((Factory<T> factory) => factory.type).toSet();
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}
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@override
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bool get sizedByParent => true;
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@override
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bool get alwaysNeedsCompositing => true;
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@override
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bool get isRepaintBoundary => true;
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_MotionEventsDispatcher _motionEventsDispatcher;
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_AndroidViewGestureRecognizer _gestureRecognizer;
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@override
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void performResize() {
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size = constraints.biggest;
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_sizePlatformView();
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}
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Size _currentAndroidViewSize;
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Future<void> _sizePlatformView() async {
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// Android virtual displays cannot have a zero size.
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// Trying to size it to 0 crashes the app, which was happening when starting the app
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// with a locked screen (see: https://github.com/flutter/flutter/issues/20456).
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if (_state == _PlatformViewState.resizing || size.isEmpty) {
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return;
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}
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_state = _PlatformViewState.resizing;
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markNeedsPaint();
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Size targetSize;
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do {
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targetSize = size;
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await _viewController.setSize(targetSize);
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_currentAndroidViewSize = targetSize;
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// We've resized the platform view to targetSize, but it is possible that
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// while we were resizing the render object's size was changed again.
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// In that case we will resize the platform view again.
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} while (size != targetSize);
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_state = _PlatformViewState.ready;
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markNeedsPaint();
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}
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@override
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void paint(PaintingContext context, Offset offset) {
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if (_viewController.textureId == null)
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return;
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// Clip the texture if it's going to paint out of the bounds of the renter box
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// (see comment in _paintTexture for an explanation of when this happens).
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if (size.width < _currentAndroidViewSize.width || size.height < _currentAndroidViewSize.height) {
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context.pushClipRect(true, offset, offset & size, _paintTexture);
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return;
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}
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_paintTexture(context, offset);
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}
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void _paintTexture(PaintingContext context, Offset offset) {
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// As resizing the Android view happens asynchronously we don't know exactly when is a
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// texture frame with the new size is ready for consumption.
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// TextureLayer is unaware of the texture frame's size and always maps it to the
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// specified rect. If the rect we provide has a different size from the current texture frame's
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// size the texture frame will be scaled.
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// To prevent unwanted scaling artifacts while resizing we freeze the texture frame, until
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// we know that a frame with the new size is in the buffer.
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// This guarantees that the size of the texture frame we're painting is always
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// _currentAndroidViewSize.
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context.addLayer(TextureLayer(
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rect: offset & _currentAndroidViewSize,
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textureId: _viewController.textureId,
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freeze: _state == _PlatformViewState.resizing,
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));
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}
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@override
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bool hitTest(HitTestResult result, { Offset position }) {
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if (hitTestBehavior == PlatformViewHitTestBehavior.transparent || !size.contains(position))
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return false;
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result.add(BoxHitTestEntry(this, position));
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return hitTestBehavior == PlatformViewHitTestBehavior.opaque;
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}
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@override
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bool hitTestSelf(Offset position) => hitTestBehavior != PlatformViewHitTestBehavior.transparent;
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@override
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void handleEvent(PointerEvent event, HitTestEntry entry) {
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if (event is PointerDownEvent) {
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_gestureRecognizer.addPointer(event);
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}
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}
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@override
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void detach() {
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_gestureRecognizer.reset();
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super.detach();
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}
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}
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class _AndroidViewGestureRecognizer extends OneSequenceGestureRecognizer {
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_AndroidViewGestureRecognizer(this.dispatcher, this.gestureRecognizerFactories) {
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team = GestureArenaTeam();
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team.captain = this;
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_gestureRecognizers = gestureRecognizerFactories.map(
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(Factory<OneSequenceGestureRecognizer> factory) {
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return factory.constructor()..team = team;
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}
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).toSet();
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}
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final _MotionEventsDispatcher dispatcher;
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// Maps a pointer to a list of its cached pointer events.
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// Before the arena for a pointer is resolved all events are cached here, if we win the arena
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// the cached events are dispatched to the view, if we lose the arena we clear the cache for
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// the pointer.
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final Map<int, List<PointerEvent>> cachedEvents = <int, List<PointerEvent>> {};
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// Pointer for which we have already won the arena, events for pointers in this set are
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// immediately dispatched to the Android view.
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final Set<int> forwardedPointers = Set<int>();
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// We use OneSequenceGestureRecognizers as they support gesture arena teams.
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// TODO(amirh): get a list of GestureRecognizers here.
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// https://github.com/flutter/flutter/issues/20953
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final Set<Factory<OneSequenceGestureRecognizer>> gestureRecognizerFactories;
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Set<OneSequenceGestureRecognizer> _gestureRecognizers;
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@override
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void addPointer(PointerDownEvent event) {
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startTrackingPointer(event.pointer);
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for (OneSequenceGestureRecognizer recognizer in _gestureRecognizers) {
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recognizer.addPointer(event);
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}
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}
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@override
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String get debugDescription => 'Android view';
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@override
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void didStopTrackingLastPointer(int pointer) {}
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@override
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void handleEvent(PointerEvent event) {
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if (!forwardedPointers.contains(event.pointer)) {
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cacheEvent(event);
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} else {
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dispatcher.handlePointerEvent(event);
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}
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stopTrackingIfPointerNoLongerDown(event);
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}
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@override
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void acceptGesture(int pointer) {
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flushPointerCache(pointer);
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forwardedPointers.add(pointer);
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}
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@override
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void rejectGesture(int pointer) {
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stopTrackingPointer(pointer);
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cachedEvents.remove(pointer);
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}
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void cacheEvent(PointerEvent event) {
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if (!cachedEvents.containsKey(event.pointer)) {
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cachedEvents[event.pointer] = <PointerEvent> [];
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}
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cachedEvents[event.pointer].add(event);
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}
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void flushPointerCache(int pointer) {
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cachedEvents.remove(pointer)?.forEach(dispatcher.handlePointerEvent);
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}
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@override
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void stopTrackingPointer(int pointer) {
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super.stopTrackingPointer(pointer);
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forwardedPointers.remove(pointer);
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}
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void reset() {
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forwardedPointers.forEach(super.stopTrackingPointer);
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forwardedPointers.clear();
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cachedEvents.keys.forEach(super.stopTrackingPointer);
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cachedEvents.clear();
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resolve(GestureDisposition.rejected);
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}
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}
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typedef _GlobalToLocal = Offset Function(Offset point);
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// Composes a stream of PointerEvent objects into AndroidMotionEvent objects
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// and dispatches them to the associated embedded Android view.
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class _MotionEventsDispatcher {
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_MotionEventsDispatcher(this.globalToLocal, this.viewController);
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final Map<int, AndroidPointerCoords> pointerPositions = <int, AndroidPointerCoords>{};
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final Map<int, AndroidPointerProperties> pointerProperties = <int, AndroidPointerProperties>{};
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final _GlobalToLocal globalToLocal;
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final AndroidViewController viewController;
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int nextPointerId = 0;
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int downTimeMillis;
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void handlePointerEvent(PointerEvent event) {
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if (event is PointerDownEvent) {
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if (nextPointerId == 0)
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downTimeMillis = event.timeStamp.inMilliseconds;
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pointerProperties[event.pointer] = propertiesFor(event, nextPointerId++);
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}
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pointerPositions[event.pointer] = coordsFor(event);
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dispatchPointerEvent(event);
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if (event is PointerUpEvent) {
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pointerPositions.remove(event.pointer);
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pointerProperties.remove(event.pointer);
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if (pointerProperties.isEmpty) {
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nextPointerId = 0;
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downTimeMillis = null;
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}
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}
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if (event is PointerCancelEvent) {
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pointerPositions.clear();
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pointerProperties.clear();
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nextPointerId = 0;
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downTimeMillis = null;
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}
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}
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void dispatchPointerEvent(PointerEvent event) {
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final List<int> pointers = pointerPositions.keys.toList();
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final int pointerIdx = pointers.indexOf(event.pointer);
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final int numPointers = pointers.length;
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// Android MotionEvent objects can batch information on multiple pointers.
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// Flutter breaks these such batched events into multiple PointerEvent objects.
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// When there are multiple active pointers we accumulate the information for all pointers
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// as we get PointerEvents, and only send it to the embedded Android view when
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// we see the last pointer. This way we achieve the same batching as Android.
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if(isSinglePointerAction(event) && pointerIdx < numPointers - 1)
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return;
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int action;
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switch(event.runtimeType){
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case PointerDownEvent:
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action = numPointers == 1 ? AndroidViewController.kActionDown
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: AndroidViewController.pointerAction(pointerIdx, AndroidViewController.kActionPointerDown);
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break;
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case PointerUpEvent:
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action = numPointers == 1 ? AndroidViewController.kActionUp
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: AndroidViewController.pointerAction(pointerIdx, AndroidViewController.kActionPointerUp);
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break;
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case PointerMoveEvent:
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action = AndroidViewController.kActionMove;
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break;
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case PointerCancelEvent:
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action = AndroidViewController.kActionCancel;
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break;
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default:
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return;
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}
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final AndroidMotionEvent androidMotionEvent = AndroidMotionEvent(
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downTime: downTimeMillis,
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eventTime: event.timeStamp.inMilliseconds,
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action: action,
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pointerCount: pointerPositions.length,
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pointerProperties: pointers.map<AndroidPointerProperties>((int i) => pointerProperties[i]).toList(),
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pointerCoords: pointers.map<AndroidPointerCoords>((int i) => pointerPositions[i]).toList(),
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metaState: 0,
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buttonState: 0,
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xPrecision: 1.0,
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yPrecision: 1.0,
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deviceId: 0,
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edgeFlags: 0,
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source: 0,
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flags: 0
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);
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viewController.sendMotionEvent(androidMotionEvent);
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}
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AndroidPointerCoords coordsFor(PointerEvent event) {
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final Offset position = globalToLocal(event.position);
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return AndroidPointerCoords(
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orientation: event.orientation,
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pressure: event.pressure,
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// Currently the engine omits the pointer size, for now I'm fixing this to 0.33 which is roughly
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// what I typically see on Android.
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//
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// TODO(amirh): Use the original pointer's size.
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// https://github.com/flutter/flutter/issues/20300
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size: 0.333,
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toolMajor: event.radiusMajor,
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toolMinor: event.radiusMinor,
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touchMajor: event.radiusMajor,
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touchMinor: event.radiusMinor,
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x: position.dx,
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y: position.dy
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);
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}
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AndroidPointerProperties propertiesFor(PointerEvent event, int pointerId) {
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int toolType = AndroidPointerProperties.kToolTypeUnknown;
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switch(event.kind) {
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case PointerDeviceKind.touch:
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toolType = AndroidPointerProperties.kToolTypeFinger;
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break;
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case PointerDeviceKind.mouse:
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toolType = AndroidPointerProperties.kToolTypeMouse;
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break;
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case PointerDeviceKind.stylus:
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toolType = AndroidPointerProperties.kToolTypeStylus;
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break;
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case PointerDeviceKind.invertedStylus:
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toolType = AndroidPointerProperties.kToolTypeEraser;
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break;
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case PointerDeviceKind.unknown:
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toolType = AndroidPointerProperties.kToolTypeUnknown;
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break;
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}
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return AndroidPointerProperties(id: pointerId, toolType: toolType);
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}
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bool isSinglePointerAction(PointerEvent event) =>
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!(event is PointerDownEvent) && !(event is PointerUpEvent);
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}
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