books

packages/idraw/lib/p14/s05.dart

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+
+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<Offset> points1 = [
+    Offset(0, 20),
+    Offset(40, 40) ,
+    Offset(80, -20),
+    Offset(120, -40),
+    Offset(160, -80),
+    Offset(200, -20),
+    Offset(240, -40),
+  ];
+  List<Offset> points2 = [
+    Offset(0, 0),
+    Offset(40, -20) ,
+    Offset(80, -40),
+    Offset(120, -80),
+    Offset(160, -40),
+    Offset(200, 20),
+    Offset(240, 40),
+  ];
+  List<Offset> 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<Offset> 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;
+}