| // Copyright 2014 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/gestures.dart'; |
| import 'package:flutter/material.dart'; |
| |
| enum _DragTarget { |
| start, |
| end |
| } |
| |
| // How close a drag's start position must be to the target point. This is |
| // a distance squared. |
| const double _kTargetSlop = 2500.0; |
| |
| // Used by the Painter classes. |
| const double _kPointRadius = 6.0; |
| |
| class _DragHandler extends Drag { |
| _DragHandler(this.onUpdate, this.onCancel, this.onEnd); |
| |
| final GestureDragUpdateCallback onUpdate; |
| final GestureDragCancelCallback onCancel; |
| final GestureDragEndCallback onEnd; |
| |
| @override |
| void update(DragUpdateDetails details) { |
| onUpdate(details); |
| } |
| |
| @override |
| void cancel() { |
| onCancel(); |
| } |
| |
| @override |
| void end(DragEndDetails details) { |
| onEnd(details); |
| } |
| } |
| |
| class _IgnoreDrag extends Drag { |
| } |
| |
| class _PointDemoPainter extends CustomPainter { |
| _PointDemoPainter({ |
| Animation<double>? repaint, |
| required this.arc, |
| }) : _repaint = repaint, super(repaint: repaint); |
| |
| final MaterialPointArcTween arc; |
| final Animation<double>? _repaint; |
| |
| void drawPoint(Canvas canvas, Offset point, Color color) { |
| final Paint paint = Paint() |
| ..color = color.withOpacity(0.25) |
| ..style = PaintingStyle.fill; |
| canvas.drawCircle(point, _kPointRadius, paint); |
| paint |
| ..color = color |
| ..style = PaintingStyle.stroke |
| ..strokeWidth = 2.0; |
| canvas.drawCircle(point, _kPointRadius + 1.0, paint); |
| } |
| |
| @override |
| void paint(Canvas canvas, Size size) { |
| final Paint paint = Paint(); |
| |
| if (arc.center != null) { |
| drawPoint(canvas, arc.center!, Colors.grey.shade400); |
| } |
| |
| paint |
| ..isAntiAlias = false // Work-around for github.com/flutter/flutter/issues/5720 |
| ..color = Colors.green.withOpacity(0.25) |
| ..strokeWidth = 4.0 |
| ..style = PaintingStyle.stroke; |
| if (arc.center != null && arc.radius != null) { |
| canvas.drawCircle(arc.center!, arc.radius!, paint); |
| } else { |
| canvas.drawLine(arc.begin!, arc.end!, paint); |
| } |
| |
| drawPoint(canvas, arc.begin!, Colors.green); |
| drawPoint(canvas, arc.end!, Colors.red); |
| |
| paint |
| ..color = Colors.green |
| ..style = PaintingStyle.fill; |
| canvas.drawCircle(arc.lerp(_repaint!.value), _kPointRadius, paint); |
| } |
| |
| @override |
| bool hitTest(Offset position) { |
| return (arc.begin! - position).distanceSquared < _kTargetSlop |
| || (arc.end! - position).distanceSquared < _kTargetSlop; |
| } |
| |
| @override |
| bool shouldRepaint(_PointDemoPainter oldPainter) => arc != oldPainter.arc; |
| } |
| |
| class _PointDemo extends StatefulWidget { |
| const _PointDemo({ super.key, required this.controller }); |
| |
| final AnimationController controller; |
| |
| @override |
| _PointDemoState createState() => _PointDemoState(); |
| } |
| |
| class _PointDemoState extends State<_PointDemo> { |
| final GlobalKey _painterKey = GlobalKey(); |
| |
| CurvedAnimation? _animation; |
| _DragTarget? _dragTarget; |
| Size? _screenSize; |
| Offset? _begin; |
| Offset? _end; |
| |
| @override |
| void initState() { |
| super.initState(); |
| _animation = CurvedAnimation(parent: widget.controller, curve: Curves.fastOutSlowIn); |
| } |
| |
| @override |
| void dispose() { |
| widget.controller.value = 0.0; |
| super.dispose(); |
| } |
| |
| Drag _handleOnStart(Offset position) { |
| // TODO(hansmuller): allow the user to drag both points at the same time. |
| if (_dragTarget != null) { |
| return _IgnoreDrag(); |
| } |
| |
| final RenderBox? box = _painterKey.currentContext!.findRenderObject() as RenderBox?; |
| final double startOffset = (box!.localToGlobal(_begin!) - position).distanceSquared; |
| final double endOffset = (box.localToGlobal(_end!) - position).distanceSquared; |
| setState(() { |
| if (startOffset < endOffset && startOffset < _kTargetSlop) { |
| _dragTarget = _DragTarget.start; |
| } else if (endOffset < _kTargetSlop) { |
| _dragTarget = _DragTarget.end; |
| } else { |
| _dragTarget = null; |
| } |
| }); |
| |
| return _DragHandler(_handleDragUpdate, _handleDragCancel, _handleDragEnd); |
| } |
| |
| void _handleDragUpdate(DragUpdateDetails details) { |
| switch (_dragTarget!) { |
| case _DragTarget.start: |
| setState(() { |
| _begin = _begin! + details.delta; |
| }); |
| case _DragTarget.end: |
| setState(() { |
| _end = _end! + details.delta; |
| }); |
| } |
| } |
| |
| void _handleDragCancel() { |
| _dragTarget = null; |
| widget.controller.value = 0.0; |
| } |
| |
| void _handleDragEnd(DragEndDetails details) { |
| _dragTarget = null; |
| } |
| |
| @override |
| Widget build(BuildContext context) { |
| final Size screenSize = MediaQuery.of(context).size; |
| if (_screenSize == null || _screenSize != screenSize) { |
| _screenSize = screenSize; |
| _begin = Offset(screenSize.width * 0.5, screenSize.height * 0.2); |
| _end = Offset(screenSize.width * 0.1, screenSize.height * 0.4); |
| } |
| |
| final MaterialPointArcTween arc = MaterialPointArcTween(begin: _begin, end: _end); |
| return RawGestureDetector( |
| behavior: _dragTarget == null ? HitTestBehavior.deferToChild : HitTestBehavior.opaque, |
| gestures: <Type, GestureRecognizerFactory>{ |
| ImmediateMultiDragGestureRecognizer: GestureRecognizerFactoryWithHandlers<ImmediateMultiDragGestureRecognizer>( |
| () => ImmediateMultiDragGestureRecognizer(), |
| (ImmediateMultiDragGestureRecognizer instance) { |
| instance.onStart = _handleOnStart; |
| }, |
| ), |
| }, |
| child: ClipRect( |
| child: CustomPaint( |
| key: _painterKey, |
| foregroundPainter: _PointDemoPainter( |
| repaint: _animation, |
| arc: arc, |
| ), |
| // Watch out: if this IgnorePointer is left out, then gestures that |
| // fail _PointDemoPainter.hitTest() will still be recognized because |
| // they do overlap this child, which is as big as the CustomPaint. |
| child: IgnorePointer( |
| child: Padding( |
| padding: const EdgeInsets.all(16.0), |
| child: Text( |
| 'Tap the refresh button to run the animation. Drag the green ' |
| "and red points to change the animation's path.", |
| style: Theme.of(context).textTheme.bodySmall?.copyWith(fontSize: 16.0), |
| ), |
| ), |
| ), |
| ), |
| ), |
| ); |
| } |
| } |
| |
| class _RectangleDemoPainter extends CustomPainter { |
| _RectangleDemoPainter({ |
| required Animation<double> repaint, |
| required this.arc, |
| }) : _repaint = repaint, super(repaint: repaint); |
| |
| final MaterialRectArcTween arc; |
| final Animation<double> _repaint; |
| |
| void drawPoint(Canvas canvas, Offset p, Color color) { |
| final Paint paint = Paint() |
| ..color = color.withOpacity(0.25) |
| ..style = PaintingStyle.fill; |
| canvas.drawCircle(p, _kPointRadius, paint); |
| paint |
| ..color = color |
| ..style = PaintingStyle.stroke |
| ..strokeWidth = 2.0; |
| canvas.drawCircle(p, _kPointRadius + 1.0, paint); |
| } |
| |
| void drawRect(Canvas canvas, Rect rect, Color color) { |
| final Paint paint = Paint() |
| ..color = color.withOpacity(0.25) |
| ..strokeWidth = 4.0 |
| ..style = PaintingStyle.stroke; |
| canvas.drawRect(rect, paint); |
| drawPoint(canvas, rect.center, color); |
| } |
| |
| @override |
| void paint(Canvas canvas, Size size) { |
| drawRect(canvas, arc.begin!, Colors.green); |
| drawRect(canvas, arc.end!, Colors.red); |
| drawRect(canvas, arc.lerp(_repaint.value), Colors.blue); |
| } |
| |
| @override |
| bool hitTest(Offset position) { |
| return (arc.begin!.center - position).distanceSquared < _kTargetSlop |
| || (arc.end!.center - position).distanceSquared < _kTargetSlop; |
| } |
| |
| @override |
| bool shouldRepaint(_RectangleDemoPainter oldPainter) => arc != oldPainter.arc; |
| } |
| |
| class _RectangleDemo extends StatefulWidget { |
| const _RectangleDemo({ super.key, required this.controller }); |
| |
| final AnimationController controller; |
| |
| @override |
| _RectangleDemoState createState() => _RectangleDemoState(); |
| } |
| |
| class _RectangleDemoState extends State<_RectangleDemo> { |
| final GlobalKey _painterKey = GlobalKey(); |
| |
| late final CurvedAnimation _animation = CurvedAnimation(parent: widget.controller, curve: Curves.fastOutSlowIn); |
| _DragTarget? _dragTarget; |
| Size? _screenSize; |
| Rect? _begin; |
| Rect? _end; |
| |
| @override |
| void dispose() { |
| widget.controller.value = 0.0; |
| super.dispose(); |
| } |
| |
| Drag _handleOnStart(Offset position) { |
| // TODO(hansmuller): allow the user to drag both points at the same time. |
| if (_dragTarget != null) { |
| return _IgnoreDrag(); |
| } |
| |
| final RenderBox? box = _painterKey.currentContext?.findRenderObject() as RenderBox?; |
| final double startOffset = (box!.localToGlobal(_begin!.center) - position).distanceSquared; |
| final double endOffset = (box.localToGlobal(_end!.center) - position).distanceSquared; |
| setState(() { |
| if (startOffset < endOffset && startOffset < _kTargetSlop) { |
| _dragTarget = _DragTarget.start; |
| } else if (endOffset < _kTargetSlop) { |
| _dragTarget = _DragTarget.end; |
| } else { |
| _dragTarget = null; |
| } |
| }); |
| return _DragHandler(_handleDragUpdate, _handleDragCancel, _handleDragEnd); |
| } |
| |
| void _handleDragUpdate(DragUpdateDetails details) { |
| switch (_dragTarget!) { |
| case _DragTarget.start: |
| setState(() { |
| _begin = _begin?.shift(details.delta); |
| }); |
| case _DragTarget.end: |
| setState(() { |
| _end = _end?.shift(details.delta); |
| }); |
| } |
| } |
| |
| void _handleDragCancel() { |
| _dragTarget = null; |
| widget.controller.value = 0.0; |
| } |
| |
| void _handleDragEnd(DragEndDetails details) { |
| _dragTarget = null; |
| } |
| |
| @override |
| Widget build(BuildContext context) { |
| final Size screenSize = MediaQuery.of(context).size; |
| if (_screenSize == null || _screenSize != screenSize) { |
| _screenSize = screenSize; |
| _begin = Rect.fromLTWH( |
| screenSize.width * 0.5, screenSize.height * 0.2, |
| screenSize.width * 0.4, screenSize.height * 0.2, |
| ); |
| _end = Rect.fromLTWH( |
| screenSize.width * 0.1, screenSize.height * 0.4, |
| screenSize.width * 0.3, screenSize.height * 0.3, |
| ); |
| } |
| |
| final MaterialRectArcTween arc = MaterialRectArcTween(begin: _begin, end: _end); |
| return RawGestureDetector( |
| behavior: _dragTarget == null ? HitTestBehavior.deferToChild : HitTestBehavior.opaque, |
| gestures: <Type, GestureRecognizerFactory>{ |
| ImmediateMultiDragGestureRecognizer: GestureRecognizerFactoryWithHandlers<ImmediateMultiDragGestureRecognizer>( |
| () => ImmediateMultiDragGestureRecognizer(), |
| (ImmediateMultiDragGestureRecognizer instance) { |
| instance.onStart = _handleOnStart; |
| }, |
| ), |
| }, |
| child: ClipRect( |
| child: CustomPaint( |
| key: _painterKey, |
| foregroundPainter: _RectangleDemoPainter( |
| repaint: _animation, |
| arc: arc, |
| ), |
| // Watch out: if this IgnorePointer is left out, then gestures that |
| // fail _RectDemoPainter.hitTest() will still be recognized because |
| // they do overlap this child, which is as big as the CustomPaint. |
| child: IgnorePointer( |
| child: Padding( |
| padding: const EdgeInsets.all(16.0), |
| child: Text( |
| 'Tap the refresh button to run the animation. Drag the rectangles ' |
| "to change the animation's path.", |
| style: Theme.of(context).textTheme.bodySmall!.copyWith(fontSize: 16.0), |
| ), |
| ), |
| ), |
| ), |
| ), |
| ); |
| } |
| } |
| |
| typedef _DemoBuilder = Widget Function(_ArcDemo demo); |
| |
| class _ArcDemo { |
| _ArcDemo(this.title, this.builder, TickerProvider vsync) |
| : controller = AnimationController(duration: const Duration(milliseconds: 500), vsync: vsync), |
| key = GlobalKey(debugLabel: title); |
| |
| final String title; |
| final _DemoBuilder builder; |
| final AnimationController controller; |
| final GlobalKey key; |
| } |
| |
| class AnimationDemo extends StatefulWidget { |
| const AnimationDemo({ super.key }); |
| |
| @override |
| State<AnimationDemo> createState() => _AnimationDemoState(); |
| } |
| |
| class _AnimationDemoState extends State<AnimationDemo> with TickerProviderStateMixin { |
| late final List<_ArcDemo> _allDemos = <_ArcDemo>[ |
| _ArcDemo('POINT', (_ArcDemo demo) { |
| return _PointDemo( |
| key: demo.key, |
| controller: demo.controller, |
| ); |
| }, this), |
| _ArcDemo('RECTANGLE', (_ArcDemo demo) { |
| return _RectangleDemo( |
| key: demo.key, |
| controller: demo.controller, |
| ); |
| }, this), |
| ]; |
| |
| Future<void> _play(_ArcDemo demo) async { |
| await demo.controller.forward(); |
| if (demo.key.currentState != null && demo.key.currentState!.mounted) { |
| demo.controller.reverse(); |
| } |
| } |
| |
| @override |
| Widget build(BuildContext context) { |
| return DefaultTabController( |
| length: _allDemos.length, |
| child: Scaffold( |
| appBar: AppBar( |
| title: const Text('Animation'), |
| bottom: TabBar( |
| tabs: _allDemos.map<Tab>((_ArcDemo demo) => Tab(text: demo.title)).toList(), |
| ), |
| ), |
| floatingActionButton: Builder( |
| builder: (BuildContext context) { |
| return FloatingActionButton( |
| child: const Icon(Icons.refresh), |
| onPressed: () { |
| _play(_allDemos[DefaultTabController.of(context).index]); |
| }, |
| ); |
| }, |
| ), |
| body: TabBarView( |
| children: _allDemos.map<Widget>((_ArcDemo demo) => demo.builder(demo)).toList(), |
| ), |
| ), |
| ); |
| } |
| } |
| |
| void main() { |
| runApp(const MaterialApp( |
| home: AnimationDemo(), |
| )); |
| } |
