84 lines
1.9 KiB
Dart
84 lines
1.9 KiB
Dart
import 'dart:ui';
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import 'package:flutter/material.dart';
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/// create by 张风捷特烈 on 2020/5/1
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/// contact me by email 1981462002@qq.com
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/// 说明:
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class Paper extends StatefulWidget {
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const Paper({super.key});
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@override
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_PaperState createState() => _PaperState();
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}
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class _PaperState extends State<Paper> with SingleTickerProviderStateMixin {
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late AnimationController _ctrl;
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double progress = 0.0;
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@override
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void initState() {
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super.initState();
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_ctrl = AnimationController(
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duration: Duration(seconds: 3), vsync: this)
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..forward();
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}
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@override
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void dispose() {
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_ctrl.dispose();
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super.dispose();
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}
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@override
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Widget build(BuildContext context) {
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return Container(
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color: Colors.white,
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child: CustomPaint(
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// 使用CustomPaint
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painter: PaperPainter(progress: _ctrl),
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),
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);
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}
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}
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class PaperPainter extends CustomPainter {
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final Animation<double> progress;
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PaperPainter({required this.progress}) : super(repaint: progress);
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@override
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void paint(Canvas canvas, Size size) {
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canvas.translate(size.width / 2, size.height / 2);
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Paint paint = Paint()
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..color = Colors.purple
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..strokeWidth = 1
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..style = PaintingStyle.stroke;
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Path path = Path();
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path
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..relativeMoveTo(0, 0)
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..relativeLineTo(-30, 120)
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..relativeLineTo(30, -30)
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..relativeLineTo(30, 30)
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..close();
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path.addOval(Rect.fromCenter(center: Offset.zero, width: 50, height: 50));
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PathMetrics pms = path.computeMetrics();
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for (PathMetric pm in pms) {
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Tangent? tangent = pm.getTangentForOffset(pm.length * progress.value);
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if(tangent ==null) continue;
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canvas.drawCircle(
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tangent.position, 5, Paint()..color = Colors.deepOrange);
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}
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canvas.drawPath(path, paint);
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}
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@override
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bool shouldRepaint(PaperPainter oldDelegate) =>
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oldDelegate.progress != progress;
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}
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