56 lines
1.4 KiB
Dart
56 lines
1.4 KiB
Dart
import 'dart:ui';
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import 'package:flutter/material.dart';
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import '../components/coordinate_pro.dart';
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/// create by 张风捷特烈 on 2020-03-19
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/// contact me by email 1981462002@qq.com
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/// 说明: 纸
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class Paper extends StatelessWidget {
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const Paper({super.key});
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@override
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Widget build(BuildContext context) {
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return Container(
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color: Colors.white,
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child: CustomPaint(
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// 使用CustomPaint
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painter: PaperPainter(),
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),
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);
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}
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}
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class PaperPainter extends CustomPainter {
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static const double step = 15; // 方格变长
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final Coordinate coordinate = Coordinate(step: step);
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// 颜色列表 256 个元素
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final List<Color> colors =
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List<Color>.generate(256, (i) => Color.fromARGB(255 - i, 255, 0, 0));
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@override
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void paint(Canvas canvas, Size size) {
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Paint paint = Paint();
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canvas.save();
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canvas.translate(size.width / 2, size.height / 2);
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// 遍历列表 绘制矩形色块
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canvas.translate(-step * 8.0, -step * 8.0);
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colors.asMap().forEach((i, color) {
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int line = (i % 16); // 行
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int row = i ~/ 16; // 列
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var topLeft = Offset(step * line, step * row);
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var rect = Rect.fromPoints(topLeft, topLeft.translate(step, step));
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canvas.drawRect(rect, paint..color = color);
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});
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canvas.restore();
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coordinate.paint(canvas, size); //绘制坐标系
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}
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@override
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bool shouldRepaint(CustomPainter oldDelegate) => false;
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}
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