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| import 'package:flutter/material.dart';
import 'dart:math' as math;
import '../example_common.dart';
class GMExampleAnimationRingPage extends StatefulWidget {
GMExampleAnimationRingPage({Key key}) : super(key: key);
@override
_GMExampleAnimationRingPageState createState() => _GMExampleAnimationRingPageState();
}
class _GMExampleAnimationRingPageState extends State<GMExampleAnimationRingPage> with SingleTickerProviderStateMixin{
AnimationController _controller;
Animation<double> angleAnim;
@override
void initState() {
// _controller = AnimationController(duration: Duration(milliseconds: 1500), vsync: this)..repeat();
_controller =
AnimationController(duration: Duration(milliseconds: 1500), vsync: this)
..repeat();
angleAnim = Tween(begin: math.pi * 1.5, end: math.pi * 3.5)
.chain(CurveTween(curve: Interval(0.5, 1.0)))
.animate(_controller);
super.initState();
}
@override
void dispose() {
_controller.dispose();
super.dispose();
}
@override
Widget build(BuildContext context) {
debugPrint("build ---------");
return Scaffold(
appBar: example_common_appBar(context, "环形动画"),
body: Center(
child: Container(
child: _buildContent(context),
height: 200,
width: 200,
color: Colors.orangeAccent,
padding: EdgeInsets.all(30.0),
),
),
floatingActionButton: FloatingActionButton(
child: Icon(Icons.account_balance),
onPressed: () {
debugPrint("status: ${_controller.status}");
if (_controller.status == AnimationStatus.forward) {
_controller.fling();
} else {
_controller.reset();
_controller..forward()..repeat();
}
},
),
);
}
Widget _buildContent(ctx) {
return AnimatedBuilder(
animation: _controller,
builder: (context, child) {
return CustomPaint(
painter: GMExampleRingDemoPainter(angleAnim.value, math.sin(_controller.value * math.pi) * math.pi),
);
},
);
}
}
//自定义绘画
class GMExampleRingDemoPainter extends CustomPainter {
final double _arcStart;
final double _arcSweep;
GMExampleRingDemoPainter(this._arcStart, this._arcSweep);
@override
void paint(Canvas canvas, Size size) {
// debugPrint("_arcStart: $_arcStart, _arcSweep:$_arcSweep");
//找到最小的一边
double side = math.min(size.width, size.height);
Paint paint = Paint()
..color = Colors.red
..strokeCap = StrokeCap.round
..strokeWidth = 4.0
..style = PaintingStyle.stroke;
canvas.drawArc(
Offset.zero & Size(side, side), _arcStart, _arcSweep, false, paint);
}
@override
bool shouldRepaint(GMExampleRingDemoPainter other) {
return _arcStart != other._arcStart || _arcSweep != other._arcSweep;
}
}
|
