books

packages/idraw/lib/p13/s02.dart

@@ -0,0 +1,123 @@
+import 'dart:math';
+import 'dart:ui';
+
+import 'package:flutter/material.dart';
+import 'dart:ui'as ui;
+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();
+
+  final List<Offset> points = [];
+
+  final double step = 6;
+  final double min = -240;
+  final double max = 240;
+
+  void initPoints() {
+    for (double x = min; x < max; x += step) {
+      points.add(Offset(x, f(x)));
+    }
+    points.add(Offset(max, f(max)));
+    points.add(Offset(max, f(max)));
+  }
+
+  void initPointsWithPolar() {
+    for (double x = min; x < max; x += step) {
+      double thta = (pi / 180 * x); // 角度转化为弧度
+      var p = f(thta);
+      points.add(Offset(p * cos(thta), p * sin(thta)));
+    }
+  }
+
+  // double f(double x) {
+  //   double y = -x * x / 200 + 100;
+  //   return y;
+  // }
+
+  // double f(double thta) {
+  //   double p = 10 * thta;
+  //   return p;
+  // }
+
+  // double f(double thta) {
+  //   double p = 100 * (1-cos(thta));
+  //   return p;
+  // }
+
+  // double f(double thta) {
+  //   double p = 150*sin(5*thta).abs();
+  //   return p;
+  // }
+
+
+  double f(double thta) { // 100*(1-4*sinθ)
+    double p =  50*(pow(e,cos(thta)) - 2 * cos(4 * thta) +pow(sin(thta / 12), 5));
+    return p;
+  }
+
+
+  @override
+  void paint(Canvas canvas, Size size) {
+    coordinate.paint(canvas, size);
+    canvas.translate(size.width / 2, size.height / 2);
+    // initPoints();
+    initPointsWithPolar();
+    Paint paint = Paint()
+      ..color = Colors.red
+      ..strokeWidth = 1.5
+      ..style = PaintingStyle.stroke;
+    var colors = [
+      Color(0xFFF60C0C),
+      Color(0xFFF3B913),
+      Color(0xFFE7F716),
+      Color(0xFF3DF30B),
+      Color(0xFF0DF6EF),
+      Color(0xFF0829FB),
+      Color(0xFFB709F4),
+    ];
+    var pos = [1.0 / 7, 2.0 / 7, 3.0 / 7, 4.0 / 7, 5.0 / 7, 6.0 / 7, 1.0];
+
+    paint.shader = ui.Gradient.linear(
+        Offset(0, 0), Offset(100, 0), colors, pos,TileMode.mirror);
+
+
+    Offset p1 = points[0];
+    Path path = Path()..moveTo(p1.dx, p1.dy);
+
+    for (var i = 1; i < points.length-1; i++) {
+      double xc = (points[i].dx + points[i + 1].dx) / 2;
+      double yc = (points[i].dy + points[i + 1].dy) / 2;
+      Offset p2 = points[i];
+      path.quadraticBezierTo(p2.dx, p2.dy, xc, yc);
+    }
+
+    canvas.drawPath(path, paint);
+
+    // canvas.drawPoints(PointMode.points, points, paint..shader=null..strokeWidth=3);
+    // canvas.drawPoints(PointMode.polygon, points, paint..shader=null..strokeWidth=1..color=Colors.blue);
+  }
+
+  @override
+  bool shouldRepaint(CustomPainter oldDelegate) => false;
+}