books

packages/idraw/lib/p15/s02.dart

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+import 'dart:ui';
+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();
+  Paint _helpPaint = Paint();
+
+  double waveWidth = 80;
+  double wrapHeight =100;
+  double waveHeight = 40;
+
+  @override
+  void paint(Canvas canvas, Size size) {
+    coordinate.paint(canvas, size);
+    canvas.translate(size.width / 2, size.height / 2);
+
+    Path path = Path();
+    Paint paint = Paint()
+      ..color = Colors.orange
+      ..style = PaintingStyle.stroke
+      ..strokeWidth = 2;
+
+
+    canvas.save();
+    canvas.translate(-2*waveWidth, 0);
+    path.moveTo(0, 0);
+    path.relativeQuadraticBezierTo(waveWidth/2, -waveHeight*2, waveWidth, 0);
+    path.relativeQuadraticBezierTo(waveWidth/2, waveHeight*2, waveWidth, 0);
+    path.relativeQuadraticBezierTo(waveWidth/2, -waveHeight*2, waveWidth, 0);
+    path.relativeQuadraticBezierTo(waveWidth/2, waveHeight*2, waveWidth, 0);
+    path.close();
+    canvas.drawPath(path, paint..style=PaintingStyle.fill);
+    canvas.restore();
+
+    _drawHelp(canvas);
+
+  }
+
+  void _drawHelp(Canvas canvas) {
+    _helpPaint
+      ..color = Colors.purple
+      ..style = PaintingStyle.stroke
+      ..strokeCap = StrokeCap.round;
+    canvas.drawRect(Rect.fromPoints(Offset(0,-100), Offset(160,100)), _helpPaint..strokeWidth=2);
+  }
+
+  @override
+  bool shouldRepaint(CustomPainter oldDelegate) => false;
+}