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| 1 | +// Copyright 2014 The Flutter Authors. All rights reserved. |
| 2 | +// Use of this source code is governed by a BSD-style license that can be |
| 3 | +// found in the LICENSE file. |
| 4 | + |
| 5 | +import 'dart:async'; |
| 6 | +import 'dart:math' show sqrt; |
| 7 | +import 'dart:typed_data'; |
| 8 | +import 'dart:ui' as ui; |
| 9 | +import 'package:flutter/material.dart'; |
| 10 | +import 'package:flutter/services.dart'; |
| 11 | + |
| 12 | +void main() { |
| 13 | + runApp(const MyApp()); |
| 14 | +} |
| 15 | + |
| 16 | +class MyApp extends StatelessWidget { |
| 17 | + const MyApp({super.key}); |
| 18 | + |
| 19 | + @override |
| 20 | + Widget build(BuildContext context) { |
| 21 | + return MaterialApp(title: 'SDF Demo', theme: ThemeData.dark(), home: const MyHomePage()); |
| 22 | + } |
| 23 | +} |
| 24 | + |
| 25 | +class MyHomePage extends StatefulWidget { |
| 26 | + const MyHomePage({super.key}); |
| 27 | + |
| 28 | + @override |
| 29 | + State<MyHomePage> createState() => _MyHomePageState(); |
| 30 | +} |
| 31 | + |
| 32 | +class _MyHomePageState extends State<MyHomePage> { |
| 33 | + @override |
| 34 | + Widget build(BuildContext context) { |
| 35 | + return const Scaffold(body: SdfCanvas()); |
| 36 | + } |
| 37 | +} |
| 38 | + |
| 39 | +class SdfCanvas extends StatefulWidget { |
| 40 | + const SdfCanvas({super.key}); |
| 41 | + |
| 42 | + @override |
| 43 | + State<SdfCanvas> createState() => _SdfCanvasState(); |
| 44 | +} |
| 45 | + |
| 46 | +class _SdfCanvasState extends State<SdfCanvas> { |
| 47 | + ui.FragmentShader? _shader; |
| 48 | + ui.Image? _sdfImage; |
| 49 | + |
| 50 | + @override |
| 51 | + void initState() { |
| 52 | + super.initState(); |
| 53 | + _loadShader().then((ui.FragmentShader shader) { |
| 54 | + setState(() { |
| 55 | + _shader = shader; |
| 56 | + }); |
| 57 | + }); |
| 58 | + _loadSdfImage().then((ui.Image image) { |
| 59 | + setState(() { |
| 60 | + _sdfImage = image; |
| 61 | + }); |
| 62 | + }); |
| 63 | + } |
| 64 | + |
| 65 | + Future<ui.FragmentShader> _loadShader() async { |
| 66 | + final ui.FragmentProgram program = await ui.FragmentProgram.fromAsset('shaders/sdf.frag'); |
| 67 | + return program.fragmentShader(); |
| 68 | + } |
| 69 | + |
| 70 | + Future<ui.Image> _loadSdfImage() async { |
| 71 | + const int width = 1024; |
| 72 | + const int height = 1024; |
| 73 | + const double radius = width / 4.0; |
| 74 | + final List<double> floats = List<double>.filled(width * height * 4, 0.0); |
| 75 | + for (int i = 0; i < height; ++i) { |
| 76 | + for (int j = 0; j < width; ++j) { |
| 77 | + double x = j.toDouble(); |
| 78 | + double y = i.toDouble(); |
| 79 | + x -= width / 2.0; |
| 80 | + y -= height / 2.0; |
| 81 | + final double length = sqrt(x * x + y * y) - radius; |
| 82 | + final int idx = i * width * 4 + j * 4; |
| 83 | + floats[idx + 0] = length - radius; |
| 84 | + floats[idx + 1] = 0.0; |
| 85 | + floats[idx + 2] = 0.0; |
| 86 | + floats[idx + 3] = 1.0; |
| 87 | + } |
| 88 | + } |
| 89 | + final Float32List floatList = Float32List.fromList(floats); |
| 90 | + final Uint8List intList = Uint8List.view(floatList.buffer); |
| 91 | + final Completer<ui.Image> completer = Completer<ui.Image>(); |
| 92 | + ui.decodeImageFromPixels( |
| 93 | + intList, |
| 94 | + width, |
| 95 | + height, |
| 96 | + ui.PixelFormat.rgbaFloat32, |
| 97 | + targetFormat: ui.TargetPixelFormat.rgbaFloat32, |
| 98 | + (ui.Image image) { |
| 99 | + completer.complete(image); |
| 100 | + }, |
| 101 | + ); |
| 102 | + return completer.future; |
| 103 | + } |
| 104 | + |
| 105 | + @override |
| 106 | + Widget build(BuildContext context) { |
| 107 | + if (_shader == null) { |
| 108 | + return const Center(child: CircularProgressIndicator()); |
| 109 | + } |
| 110 | + return SizedBox.expand( |
| 111 | + child: (_shader != null && _sdfImage != null) |
| 112 | + ? CustomPaint(painter: SdfPainter(_shader!, _sdfImage!)) |
| 113 | + : Container(), |
| 114 | + ); |
| 115 | + } |
| 116 | +} |
| 117 | + |
| 118 | +class SdfPainter extends CustomPainter { |
| 119 | + SdfPainter(this.shader, this.image); |
| 120 | + |
| 121 | + final ui.FragmentShader shader; |
| 122 | + final ui.Image image; |
| 123 | + |
| 124 | + @override |
| 125 | + void paint(Canvas canvas, Size size) { |
| 126 | + shader.setFloat(0, size.width); |
| 127 | + shader.setFloat(1, size.height); |
| 128 | + shader.setImageSampler(0, image); |
| 129 | + final Paint paint = Paint()..shader = shader; |
| 130 | + canvas.drawRect(Offset.zero & size, paint); |
| 131 | + } |
| 132 | + |
| 133 | + @override |
| 134 | + bool shouldRepaint(covariant CustomPainter oldDelegate) { |
| 135 | + return true; |
| 136 | + } |
| 137 | +} |
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