books

assets/draw/p08/s04.dart

@@ -0,0 +1,98 @@
+import 'dart:async';
+import 'dart:typed_data';
+
+import 'package:flutter/cupertino.dart';
+import 'package:flutter/material.dart';
+import 'dart:ui' as ui;
+
+import 'package:flutter/services.dart';
+
+import '../components/coordinate_pro.dart';
+
+
+
+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();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      color: Colors.white,
+      child: CustomPaint(
+        painter: ImageShaderPainter(_img),
+      ),
+    );
+  }
+
+  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());
+  }
+}
+
+class ImageShaderPainter extends CustomPainter {
+  ui.Image? img;
+
+  ImageShaderPainter(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);
+
+    Paint paint = Paint()..shader = ImageShader(
+        img!,
+        TileMode.repeated,
+        TileMode.repeated,
+        Float64List.fromList([
+          1, 0, 0, 0,
+          0, 1, 0, 0,
+          0, 0, 1, 0,
+          0, 0, 0, 1,
+        ]));
+
+    canvas.drawCircle(Offset(100, 100), 50, paint);
+
+    canvas.translate(120, 0);
+
+    canvas.drawCircle(
+        Offset(100, 100),
+        50,
+        paint
+          ..strokeWidth = 10
+          ..style = PaintingStyle.stroke);
+
+    canvas.translate(-120*2.0, 0);
+
+    canvas.drawLine(
+        Offset(100 , 50),
+        Offset(100 , 50 + 100.0),
+        paint
+          ..strokeWidth = 30
+          ..style = PaintingStyle.stroke);
+  }
+
+  @override
+  bool shouldRepaint(CustomPainter oldDelegate) => true;
+}