books

assets/draw/p08/s08.dart

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+import 'dart:async';
+import 'dart:math';
+
+import 'package:flutter/cupertino.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
+import 'dart:ui' as ui;
+
+import '../components/coordinate_pro.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 StatefulWidget {
+  const Paper({super.key});
+
+  @override
+  _PaperState createState() => _PaperState();
+}
+
+class _PaperState extends State<Paper> {
+  ui.Image? _img;
+
+  bool get hasImage => _img != null;
+
+  @override
+  void initState() {
+    super.initState();
+    _loadImage();
+  }
+  void _loadImage() async {
+    _img = await loadImageFromAssets('assets/images/wy_200x300.jpg');
+    setState(() {});
+  }
+
+  //读取 assets 中的图片
+  Future<ui.Image>? loadImageFromAssets(String path) async {
+    ByteData data = await rootBundle.load(path);
+    return decodeImageFromList(data.buffer.asUint8List());
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      color: Colors.white,
+      child: CustomPaint(
+        painter: PaperPainter(_img),
+      ),
+    );
+  }
+}
+
+class PaperPainter extends CustomPainter {
+  ui.Image? img;
+
+  PaperPainter(this.img);
+
+  Coordinate coordinate = Coordinate();
+
+  @override
+  void paint(Canvas canvas, Size size) {
+    if (img == null) return;
+    coordinate.paint(canvas, size);
+    canvas.translate(size.width / 2, size.height / 2);
+    canvas.translate(-120 * 2.0 - imgW / 4, -imgH / 4);
+    drawImageFilter(canvas);
+  }
+
+  double get imgW => img!.width.toDouble();
+
+  double get imgH => img!.height.toDouble();
+
+  void drawImageFilter(Canvas canvas) {
+    var paint = Paint();
+    _drawImage(canvas, paint);
+
+    paint.imageFilter = ui.ImageFilter.blur(sigmaX: 0.4, sigmaY: 0.4);
+    _drawImage(canvas, paint);
+
+    paint.imageFilter = ui.ImageFilter.blur(sigmaX: 0.6, sigmaY: 0.6);
+    _drawImage(canvas, paint);
+
+    paint.imageFilter = ui.ImageFilter.blur(sigmaX: 0.8, sigmaY: 0.8);
+    _drawImage(canvas, paint);
+
+    paint.imageFilter = ui.ImageFilter.matrix(Matrix4.skew(pi / 8, 0).storage);
+    _drawImage(canvas, paint);
+  }
+
+  void _drawImage(Canvas canvas, Paint paint) {
+    canvas.drawImageRect(img!, Rect.fromLTRB(0, 0, imgW, imgH),
+        Rect.fromLTRB(0, 0, imgW / 2, imgH / 2), paint);
+    canvas.translate(120, 0);
+  }
+
+  @override
+  bool shouldRepaint(CustomPainter oldDelegate) => true;
+}