floyd-steinberg-dithering/lib/Dither.dart

import 'dart:html';
import 'dart:typed_data';

class Pixel {
  int x;
  int y;
  int r;
  int g;
  int b;
  int a;

  Pixel(this.x, this.y, this.r, this.g, this.b, this.a);

  int getBytePos(int imageWidth) {
    return (x+y*imageWidth)*4;
  }

  void setRGB(int r, int g, int b) {
    this.r = r;
    this.g = g;
    this.b = b;
  }

  @override
  String toString() {
    return 'Pixel at $x, $y: {r: $r, g: $g, b: $b, a: $a}';
  }


}

class PixelArray {
  List<List<Pixel>> pixels;

  PixelArray(int width, int height) {
    pixels = new List.filled(height, new List(width));
  }

  PixelArray.fromByteArray(Uint8ClampedList array, int imageWidth) {
    pixels = new List(array.length~/imageWidth~/4);
    int y = 0;
    int x = 0;
    pixels[y] = new List(imageWidth);
    print(pixels[0].length.toString() + ","+ pixels.length.toString());
    for (var pos = 0; pos < array.length; pos = pos + 4) {
      if (x >= imageWidth) {
        x = 0;
        y++;
        pixels[y] = new List(imageWidth);
      }
      pixels[y][x] = new Pixel(x, y, array[pos], array[pos+1], array[pos+2], array[pos+3]);
      x++;
    }
  }

  PixelArray.fromImageData(ImageData imagedata, int imageWidth): this.fromByteArray(imagedata.data, imageWidth);

  PixelArray.fromPixelArray(PixelArray pixelArray) {
    pixels = new List<List<Pixel>>.from(pixelArray.pixels);
  }

  Uint8ClampedList toByteArray() {
    //TODO: look for longest array, or each line separately. Only gets width from line 1 currently.
    Uint8ClampedList result = new Uint8ClampedList(getHeight()*getWidth()*4);
    int x = 0;
    int y = 0;
    for (var i = 0; i < result.length; i = i + 4) {
      if (x >= getWidth()) {
        y++;
        x = 0;
      }
      result[i] = pixels[y][x].r;
      result[i+1] = pixels[y][x].g;
      result[i+2] = pixels[y][x].b;
      result[i+3] = pixels[y][x].a;

      x++;
    }

    return result;
  }

  ImageData toImageData() {
    return new ImageData(this.toByteArray(), this.getWidth(), this.getHeight());
  }

  Pixel getPixel(int x, int y) {
    return pixels[y][x];
  }

  void setPixel(Pixel pixel, [int x, int y]) {
    if (x != null && y != null && pixels[y] != null && pixels[y].length >= x) {
      pixel.x = x;
      pixel.y = y;
      pixels[y][x] = pixel;
      return;
    } else if (pixels.length < pixel.y || pixels[y].length < pixel.x) {
      return;
    } else {
      pixels[pixel.y][pixel.x] = pixel;
      return;
    }
  }

  int getWidth() {
    return pixels[0].length;
  }

  int getHeight() {
    return pixels.length;
  }
}