pixelate function

Image pixelate(Image src, { required int size, PixelateMode mode = PixelateMode.upperLeft, num amount = 1, Image? mask, Channel maskChannel = Channel.luminance, })

Pixelate the src image.

size determines the size of the pixelated blocks. If mode is PixelateMode.upperLeft then the upper-left corner of the block will be used for the block color. Otherwise if mode is PixelateMode.average, the average of all the pixels in the block will be used for the block color.

Implementation

Image pixelate(Image src,
    {required int size,
    PixelateMode mode = PixelateMode.upperLeft,
    num amount = 1,
    Image? mask,
    Channel maskChannel = Channel.luminance}) {
  if (size <= 1) {
    return src;
  }
  if (src.hasPalette) {
    src = src.convert(numChannels: src.numChannels);
  }
  for (final frame in src.frames) {
    final w = frame.width;
    final h = frame.height;
    switch (mode) {
      case PixelateMode.upperLeft:
        for (final p in frame) {
          final x2 = (p.x ~/ size) * size;
          final y2 = (p.y ~/ size) * size;
          final p2 = frame.getPixel(x2, y2);
          final msk =
              mask?.getPixel(p.x, p.y).getChannelNormalized(maskChannel);
          final mx = (msk ?? 1) * amount;
          if (mx == 1) {
            p.set(p2);
          } else {
            p
              ..r = mix(p.r, p2.r, mx)
              ..g = mix(p.g, p2.g, mx)
              ..b = mix(p.b, p2.b, mx)
              ..a = mix(p.a, p2.a, mx);
          }
        }
        break;
      case PixelateMode.average:
        num r = 0;
        num g = 0;
        num b = 0;
        num a = 0;
        var lx = -1;
        var ly = -1;
        for (final p in frame) {
          final x2 = (p.x ~/ size) * size;
          final y2 = (p.y ~/ size) * size;
          final msk =
              mask?.getPixel(p.x, p.y).getChannelNormalized(maskChannel);
          final mx = (msk ?? 1) * amount;
          if (x2 != lx || y2 <= ly) {
            lx = x2;
            ly = y2;
            r = 0;
            g = 0;
            b = 0;
            a = 0;
            for (var by = 0, by2 = y2; by < size && by2 < h; ++by, ++by2) {
              for (var bx = 0, bx2 = x2; bx < size && bx2 < w; ++bx, ++bx2) {
                final p2 = frame.getPixel(bx2, by2);
                r += p2.r;
                g += p2.g;
                b += p2.b;
                a += p2.a;
              }
            }
            final total = size * size;
            r /= total;
            g /= total;
            b /= total;
            a /= total;
          }

          p
            ..r = mix(p.r, r, mx)
            ..g = mix(p.g, g, mx)
            ..b = mix(p.b, b, mx)
            ..a = mix(p.a, a, mx);
        }
        break;
    }
  }
  return src;
}