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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,170 @@ | ||
| import 'dart:ui'; | ||
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|
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| import 'package:flutter/material.dart'; | ||
| import 'package:flutter_dojo/common/main_title_widget.dart'; | ||
| import 'package:flutter_dojo/common/subtitle_widget.dart'; | ||
|
|
||
| class CurveLineWidget extends StatefulWidget { | ||
| @override | ||
| _CurveLineWidgetState createState() => _CurveLineWidgetState(); | ||
| } | ||
|
|
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| class _CurveLineWidgetState extends State<CurveLineWidget> with SingleTickerProviderStateMixin { | ||
| AnimationController _controller; | ||
| Animation _animation; | ||
| double _fraction = 0.0; | ||
| int _seconds = 3; | ||
| Path _path; | ||
| GlobalKey customPaintKey = GlobalKey(); | ||
|
|
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| @override | ||
| void initState() { | ||
| _controller = AnimationController( | ||
| vsync: this, | ||
| duration: Duration(seconds: _seconds), | ||
| ); | ||
| super.initState(); | ||
| } | ||
|
|
||
| @override | ||
| void dispose() { | ||
| _controller.dispose(); | ||
| super.dispose(); | ||
| } | ||
|
|
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| @override | ||
| Widget build(BuildContext context) { | ||
| return Column( | ||
| children: <Widget>[ | ||
| MainTitleWidget('通过PathMetrics计算Path上的坐标'), | ||
| SubtitleWidget('通过getTangentForOffset获取点的Position'), | ||
| Expanded( | ||
| child: Container( | ||
| constraints: BoxConstraints.expand(), | ||
| child: CustomPaint( | ||
| key: customPaintKey, | ||
| painter: PathPainter(_path, _fraction), | ||
| ), | ||
| ), | ||
| ), | ||
| RaisedButton( | ||
| onPressed: startPathMotion, | ||
| child: Text('Start'), | ||
| ), | ||
| SubtitleWidget('通过extractPath截取Path片段'), | ||
| Expanded( | ||
| child: Container( | ||
| constraints: BoxConstraints.expand(), | ||
| child: CustomPaint( | ||
| painter: PathSegmentPainter(_path, _fraction), | ||
| ), | ||
| ), | ||
| ), | ||
| RaisedButton( | ||
| onPressed: startPathMotion, | ||
| child: Text('Start'), | ||
| ), | ||
| ], | ||
| ); | ||
| } | ||
|
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| Path _getPath(Size size) { | ||
| Path path = Path(); | ||
| path.moveTo(20, 20); | ||
| path.cubicTo( | ||
| size.width / 4, | ||
| size.height / 2, | ||
| size.width / 4 * 3, | ||
| size.height / 2, | ||
| size.width - 20, | ||
| size.height - 20, | ||
| ); | ||
| return path; | ||
| } | ||
|
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||
| startPathMotion() { | ||
| _controller.reset(); | ||
| RenderBox renderBox = customPaintKey.currentContext.findRenderObject(); | ||
| Size s = renderBox.size; | ||
| _path = _getPath(s); | ||
| PathMetrics pms = _path.computeMetrics(); | ||
| PathMetric pm = pms.elementAt(0); | ||
| double len = pm.length; | ||
| _animation = Tween(begin: 0.0, end: len).animate(_controller) | ||
| ..addListener(() { | ||
| setState(() => _fraction = _animation.value); | ||
| }) | ||
| ..addStatusListener((status) { | ||
| if (status == AnimationStatus.completed) { | ||
| _controller.stop(); | ||
| } | ||
| }); | ||
| _controller.forward(); | ||
| } | ||
| } | ||
|
|
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| class PathPainter extends CustomPainter { | ||
| double _fraction; | ||
| Path _path; | ||
|
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| PathPainter(this._path, this._fraction); | ||
|
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| Paint _paint = Paint() | ||
| ..color = Colors.blue | ||
| ..style = PaintingStyle.stroke | ||
| ..strokeWidth = 4.0; | ||
|
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| Paint _paint2 = Paint() | ||
| ..color = Colors.red | ||
| ..style = PaintingStyle.fill; | ||
|
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| @override | ||
| void paint(Canvas canvas, Size size) { | ||
| if (_path == null) { | ||
| return; | ||
| } | ||
| PathMetrics pms = _path.computeMetrics(); | ||
| PathMetric pm = pms.elementAt(0); | ||
| Tangent t = pm.getTangentForOffset(_fraction); | ||
| canvas.drawPath(_path, _paint); | ||
| canvas.drawCircle(t.position, 10, _paint2); | ||
| } | ||
|
|
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| @override | ||
| bool shouldRepaint(CustomPainter oldDelegate) { | ||
| return true; | ||
| } | ||
| } | ||
|
|
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| class PathSegmentPainter extends CustomPainter { | ||
| double _fraction; | ||
| Path _path; | ||
|
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| PathSegmentPainter(this._path, this._fraction); | ||
|
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| Paint _paint = Paint() | ||
| ..color = Colors.blue | ||
| ..style = PaintingStyle.stroke | ||
| ..strokeWidth = 4.0; | ||
|
|
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| @override | ||
| void paint(Canvas canvas, Size size) { | ||
| if (_path == null) { | ||
| return; | ||
| } | ||
| Path segmentPath = Path(); | ||
|
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||
| PathMetrics pms = _path.computeMetrics(); | ||
| PathMetric pm = pms.elementAt(0); | ||
|
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| var extractPath = pm.extractPath(0.0, _fraction); | ||
| segmentPath.addPath(extractPath, Offset(0, 0)); | ||
|
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| canvas.drawPath(segmentPath, _paint); | ||
| } | ||
|
|
||
| @override | ||
| bool shouldRepaint(CustomPainter oldDelegate) { | ||
| return true; | ||
| } | ||
| } |
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