98 lines
2.2 KiB
Dart
98 lines
2.2 KiB
Dart
import 'dart:async';
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import 'dart:typed_data';
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import 'package:flutter/cupertino.dart';
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import 'package:flutter/material.dart';
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import 'dart:ui' as ui;
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import 'package:flutter/services.dart';
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class Paper extends StatefulWidget {
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const Paper({super.key});
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@override
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_PaperState createState() => _PaperState();
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}
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class _PaperState extends State<Paper> {
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ui.Image? _img;
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bool get hasImage => _img != null;
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@override
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void initState() {
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_loadImage();
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super.initState();
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}
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@override
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Widget build(BuildContext context) {
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return Container(
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child: hasImage
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? CustomPaint(
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painter: ImageShaderPainter(_img),
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)
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: Container(),
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);
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}
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void _loadImage() async {
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_img = await loadImage(AssetImage('assets/images/wy_200x300.jpg'));
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setState(() {});
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}
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late ImageStreamListener listener;
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//异步加载图片成为ui.Image
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Future<ui.Image> loadImage(ImageProvider provider) {
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Completer<ui.Image> completer = Completer<ui.Image>();
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ImageStream stream = provider.resolve(ImageConfiguration());
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listener = ImageStreamListener((info, syno) {
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final ui.Image image = info.image; //监听图片流，获取图片
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completer.complete(image);
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stream.removeListener(listener);
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});
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stream.addListener(listener);
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return completer.future;
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}
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}
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class ImageShaderPainter extends CustomPainter {
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ui.Image? img;
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late Paint _paint;
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ImageShaderPainter(this.img) {
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_paint = Paint();
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}
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@override
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void paint(Canvas canvas, Size size) {
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if(img==null) return;
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_paint.shader = ImageShader(
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img!,
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TileMode.repeated,
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TileMode.repeated,
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Float64List.fromList([
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1, 0, 0, 0,
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0, 1, 0, 0,
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0, 0, 1, 0,
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0, 0, 0, 1,
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]));
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canvas.drawCircle(Offset(100, 100), 50, _paint);
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canvas.drawCircle(
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Offset(100 + 120.0, 100),
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50,
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_paint
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..strokeWidth = 10
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..style = PaintingStyle.stroke);
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canvas.drawLine(
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Offset(100 + 120.0 * 2, 50),
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Offset(100 + 120.0 * 2, 50 + 100.0),
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_paint
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..strokeWidth = 30
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..style = PaintingStyle.stroke);
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}
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@override
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bool shouldRepaint(CustomPainter oldDelegate) => true;
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}
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