99 lines
2.4 KiB
Dart
99 lines
2.4 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 'package:flutter/services.dart';
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import 'dart:ui' as ui;
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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 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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super.initState();
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_loadImage();
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}
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void _loadImage() async {
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_img = await loadImageFromAssets('assets/images/wy_200x300.jpg');
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setState(() {});
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}
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//读取 assets 中的图片
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Future<ui.Image>? loadImageFromAssets(String path) async {
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ByteData data = await rootBundle.load(path);
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Uint8List bytes = data.buffer.asUint8List(data.offsetInBytes, data.lengthInBytes);
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return decodeImageFromList(bytes);
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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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color: Colors.white,
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child: CustomPaint(
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painter: PaperPainter(_img),
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));
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}
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}
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class PaperPainter extends CustomPainter {
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ui.Image? img;
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PaperPainter(this.img);
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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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drawColorFilter(canvas);
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}
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double get imgW => img?.width.toDouble()??0;
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double get imgH => img?.height.toDouble()??0;
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void drawColorFilter(Canvas canvas) {
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var paint = Paint();
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paint.colorFilter = ColorFilter.linearToSrgbGamma();
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_drawImage(canvas, paint, move: false);
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paint.colorFilter = ColorFilter.mode(Colors.yellow, BlendMode.modulate);
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_drawImage(canvas, paint);
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paint.colorFilter = ColorFilter.mode(Colors.yellow, BlendMode.difference);
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_drawImage(canvas, paint);
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paint.colorFilter = ColorFilter.mode(Colors.blue, BlendMode.plus);
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_drawImage(canvas, paint);
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paint.colorFilter = ColorFilter.mode(Colors.blue, BlendMode.lighten);
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_drawImage(canvas, paint);
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}
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void _drawImage(Canvas canvas, Paint paint, {bool move = true}) {
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if (move) {
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canvas.translate(120, 0);
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} else {
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canvas.translate(20, 20);
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}
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canvas.drawImageRect(img!, Rect.fromLTRB(0, 0, imgW, imgH),
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Rect.fromLTRB(0, 0, imgW / 2, imgH / 2), paint);
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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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