import 'package:flutter/material.dart'; import '../components/coordinate_pro.dart'; /// create by 张风捷特烈 on 2020/5/1 /// contact me by email 1981462002@qq.com /// 说明: class Paper extends StatelessWidget { const Paper({super.key}); @override Widget build(BuildContext context) { return Container( color: Colors.white, child: CustomPaint( // 使用CustomPaint painter: PaperPainter(), ), ); } } class PaperPainter extends CustomPainter { final Coordinate coordinate = Coordinate(); List points1 = [ Offset(0, 20), Offset(40, 40) , Offset(80, -20), Offset(120, -40), Offset(160, -80), Offset(200, -20), Offset(240, -40), ]; List points2 = [ Offset(0, 0), Offset(40, -20) , Offset(80, -40), Offset(120, -80), Offset(160, -40), Offset(200, 20), Offset(240, 40), ]; List helpPoints = [ ]; Paint _helpPaint = Paint(); Path _linePath = Path(); @override void paint(Canvas canvas, Size size) { coordinate.paint(canvas, size); canvas.translate(size.width / 2, size.height / 2); Paint paint = Paint() ..color = Colors.red ..style = PaintingStyle.stroke ..strokeWidth = 1; Path path = Path(); addBezierPathWithPoints(path, points2); canvas.drawPath(path, paint); addBezierPathWithPoints(_linePath, points1); canvas.drawPath(_linePath, paint..color=Colors.orange); _drawHelp(canvas); } void addBezierPathWithPoints(Path path, List points) { for (int i = 0; i < points.length - 1; i++) { Offset current = points[i]; Offset next = points[i+1]; if (i == 0) { path.moveTo(current.dx, current.dy); // 控制点 double ctrlX = current.dx + (next.dx - current.dx) / 2; double ctrlY = next.dy; path.quadraticBezierTo(ctrlX, ctrlY, next.dx, next.dy); } else if (i < points.length - 2) { // 控制点 1 double ctrl1X = current.dx + (next.dx - current.dx) / 2; double ctrl1Y = current.dy; // 控制点 2 double ctrl2X = ctrl1X; double ctrl2Y = next.dy; path.cubicTo(ctrl1X,ctrl1Y,ctrl2X,ctrl2Y,next.dx,next.dy); }else{ // 控制点 double ctrlX = (next.dx - current.dx) / 2; double ctrlY = 0; path.relativeQuadraticBezierTo(ctrlX, ctrlY, next.dx-current.dx, next.dy-current.dy); } } } void _drawHelp(Canvas canvas) { _helpPaint ..style = PaintingStyle.stroke; points1.forEach((element) { canvas.drawCircle(element, 2, _helpPaint..strokeWidth=1..color=Colors.orange); }); points2.forEach((element) { canvas.drawCircle(element, 2, _helpPaint..strokeWidth=1..color=Colors.red); }); // canvas.drawPoints(PointMode.polygon, points1, _helpPaint..strokeWidth=0.5..color=Colors.red);// _drawHelp(canvas); // canvas.drawPoints(PointMode.polygon, points2, _helpPaint..strokeWidth=0.5..color=Colors.red);// _drawHelp(canvas); // canvas.drawPoints(PointMode.polygon, helpPoints, _helpPaint..strokeWidth=0.5..color=Colors.red);// _drawHelp(canvas); // _helpPaint // ..color = Colors.purple // ..style = PaintingStyle.stroke // ..strokeCap = StrokeCap.round; // canvas.drawPoints(PointMode.lines, [Offset.zero, p1, p1, p2], // _helpPaint..strokeWidth = 1); // canvas.drawPoints(PointMode.points, [Offset.zero, p1, p1, p2], // _helpPaint..strokeWidth = 8); } @override bool shouldRepaint(CustomPainter oldDelegate) => false; }