venera/lib/utils/image.dart

import 'dart:isolate';
import 'dart:typed_data';
import 'dart:ui' as ui;
import 'package:flutter/services.dart';
import 'package:flutter_qjs/flutter_qjs.dart';
import 'package:lodepng_flutter/lodepng_flutter.dart' as lodepng;

class Image {
  final Uint32List _data;

  final int width;

  final int height;

  Image(this._data, this.width, this.height);

  Image.empty(this.width, this.height) : _data = Uint32List(width * height);

  static Future<Image> decodeImage(Uint8List data) async {
    var codec = await ui.instantiateImageCodec(data);
    var frame = await codec.getNextFrame();
    codec.dispose();
    var info = await frame.image.toByteData();
    if (info == null) {
      throw Exception('Failed to decode image');
    }
    var image = Image(
      Uint32List.fromList(info.buffer.asUint32List()),
      frame.image.width,
      frame.image.height,
    );
    frame.image.dispose();
    return image;
  }

  Image copyRange(int x, int y, int width, int height) {
    var data = Uint32List(width * height);
    for (var j = 0; j < height; j++) {
      for (var i = 0; i < width; i++) {
        data[j * width + i] = _data[(j + y) * this.width + i + x];
      }
    }
    return Image(data, width, height);
  }

  void fillImageAt(int x, int y, Image image) {
    for (var j = 0; j < image.height && (j + y) < height; j++) {
      for (var i = 0; i < image.width && (i + x) < width; i++) {
        _data[(j + y) * width + i + x] = image._data[j * image.width + i];
      }
    }
  }

  Image copyAndRotate90() {
    var data = Uint32List(width * height);
    for (var j = 0; j < height; j++) {
      for (var i = 0; i < width; i++) {
        data[i * height + height - j - 1] = _data[j * width + i];
      }
    }
    return Image(data, height, width);
  }

  Color getPixel(int x, int y) {
    return Color.fromValue(_data[y * width + x]);
  }

  void setPixel(int x, int y, Color color) {
    _data[y * width + x] = color.value;
  }

  Image subImage(int x, int y, int width, int height) {
    var data = Uint32List.sublistView(
      _data,
      y * this.width + x,
      width * height,
    );
    return Image(data, width, height);
  }

  Uint8List encodePng() {
    return lodepng.encodePng(lodepng.Image(
      _data.buffer.asUint8List(),
      width,
      height,
    ));
  }
}

class Color {
  final int value;

  Color(int r, int g, int b, [int a = 255])
      : value = (a << 24) | (r << 16) | (g << 8) | b;

  Color.fromValue(this.value);

  int get r => (value >> 16) & 0xFF;

  int get g => (value >> 8) & 0xFF;

  int get b => value & 0xFF;

  int get a => (value >> 24) & 0xFF;
}

class JsEngine {
  static final JsEngine _instance = JsEngine._();

  factory JsEngine() => _instance;

  JsEngine._() {
    _engine = FlutterQjs();
    _engine!.dispatch();
    var setGlobalFunc =
        _engine!.evaluate("(key, value) => { this[key] = value; }");
    (setGlobalFunc as JSInvokable)(["sendMessage", _messageReceiver]);
    setGlobalFunc.free();
  }

  FlutterQjs? _engine;

  dynamic runCode(String js, [String? name]) {
    return _engine!.evaluate(js, name: name);
  }

  var images = <int, Image>{};

  int _key = 0;

  int setImage(Image image) {
    var key = _key++;
    images[key] = image;
    return key;
  }

  Object? _messageReceiver(dynamic message) {
    if (message is! Map) return null;
    var method = message['method'];
    if (method == 'image') {
      switch (message['function']) {
        case 'copyRange':
          var key = message['key'];
          var image = images[key];
          if (image == null) return null;
          var x = message['x'];
          var y = message['y'];
          var width = message['width'];
          var height = message['height'];
          var newImage = image.copyRange(x, y, width, height);
          return setImage(newImage);
        case 'copyAndRotate90':
          var key = message['key'];
          var image = images[key];
          if (image == null) return null;
          var newImage = image.copyAndRotate90();
          return setImage(newImage);
        case 'fillImageAt':
          var key = message['key'];
          var image = images[key];
          if (image == null) return null;
          var x = message['x'];
          var y = message['y'];
          var key2 = message['image'];
          var image2 = images[key2];
          if (image2 == null) return null;
          image.fillImageAt(x, y, image2);
          return null;
        case 'subImage':
          var key = message['key'];
          var image = images[key];
          if (image == null) return null;
          var x = message['x'];
          var y = message['y'];
          var width = message['width'];
          var height = message['height'];
          var newImage = image.subImage(x, y, width, height);
          return setImage(newImage);
        case 'getWidth':
          var key = message['key'];
          var image = images[key];
          if (image == null) return null;
          return image.width;
        case 'getHeight':
          var key = message['key'];
          var image = images[key];
          if (image == null) return null;
          return image.height;
        case 'emptyImage':
          var width = message['width'];
          var height = message['height'];
          var newImage = Image.empty(width, height);
          return setImage(newImage);
      }
    }
    return null;
  }
}

var _tasksCount = 0;

Future<Uint8List> modifyImageWithScript(Uint8List data, String script) async {
  while (_tasksCount > 3) {
    await Future.delayed(const Duration(milliseconds: 200));
  }
  _tasksCount++;
  try {
    var image = await Image.decodeImage(data);
    var initJs = await rootBundle.loadString('assets/init.js');
    return await Isolate.run(() {
      var jsEngine = JsEngine();
      jsEngine.runCode(initJs, '<init>');
      jsEngine.runCode(script);
      var key = jsEngine.setImage(image);
      var res = jsEngine.runCode('''
      let image = new Image($key);
      let result = modifyImage(image);
      return result.key;
    ''');
      var newImage = jsEngine.images[res];
      var data = newImage!.encodePng();
      return data;
    });
  }
  finally {
    _tasksCount--;
  }
}