books

assets/draw/p03/s06.dart

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+import 'dart:math';
+import 'dart:typed_data';
+import 'dart:ui';
+
+import 'package:flutter/cupertino.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
+
+import '../components/coordinate.dart';
+
+/// create by 张风捷特烈 on 2020-03-19
+/// contact me by email 1981462002@qq.com
+/// 说明: 纸
+
+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();
+
+  late Paint _paint;
+
+  final double strokeWidth = 0.5;
+  final Color color = Colors.blue;
+
+  PaperPainter() {
+    _paint = Paint()
+      ..style = PaintingStyle.fill
+      ..strokeWidth = strokeWidth
+      ..color = color;
+  }
+
+  @override
+  void paint(Canvas canvas, Size size) {
+    coordinate.paint(canvas, size);
+    canvas.translate(size.width / 2, size.height / 2);
+    _draw(canvas);
+  }
+
+  void _draw(Canvas canvas) {
+    canvas.save();
+    canvas.translate(-200, 0);
+    canvas.drawCircle(Offset(0, 0), 60, _paint);
+    canvas.restore();
+
+    var rect = Rect.fromCenter(center: Offset(0, 0), height: 100, width: 120);
+    canvas.drawOval(rect, _paint);
+
+    canvas.save();
+    canvas.translate(200, 0);
+    //drawArc(矩形区域,起始弧度,扫描弧度,是否连中心,画笔)
+    canvas.drawArc(rect, 0, pi / 2 * 3, true, _paint);
+    canvas.restore();
+  }
+
+  void _drawArcDetail(Canvas canvas) {
+    var rect = Rect.fromCenter(center: Offset(0, 0), height: 100, width: 100);
+    _paint
+      ..style = PaintingStyle.stroke
+      ..strokeWidth = 2;
+    canvas.save();
+    canvas.translate(-200, 0);
+    canvas.drawArc(rect, 0, pi / 2 * 3, false, _paint);
+    canvas.restore();
+    canvas.drawArc(rect, 0, pi / 2 * 3, true, _paint);
+    canvas.save();
+    canvas.translate(200, 0);
+    var a = pi / 8;
+    canvas.drawArc(rect, a, 2 * pi - a.abs() * 2, true, _paint..color=Colors.yellowAccent..style=PaintingStyle.fill);
+    canvas.translate(40, 0);
+    canvas.drawCircle(Offset(0, 0), 6, _paint);
+    canvas.translate(25, 0);
+    canvas.drawCircle(Offset(0, 0), 6, _paint);
+    canvas.restore();
+  }
+
+  @override
+  bool shouldRepaint(CustomPainter oldDelegate) => false;
+}