encodeImage method

@override List<int> encodeImage(Image image)

Encode a single image.

Implementation

@override
List<int> encodeImage(Image image) {
  final out = OutputBuffer();

  final bytesPerPixel = image.channels == Channels.rgb ? 3 : 4;
  final bpp = bytesPerPixel * 8;
  final rgbSize = image.width * image.height * bytesPerPixel;
  const headerSize = 54;
  const headerInfoSize = 40;
  final fileSize = rgbSize + headerSize;

  out.writeUint16(BitmapFileHeader.BMP_HEADER_FILETYPE);
  out.writeUint32(fileSize);
  out.writeUint32(0); // reserved

  out.writeUint32(headerSize);
  out.writeUint32(headerInfoSize);
  out.writeUint32(image.width);
  out.writeUint32(-image.height);
  out.writeUint16(1); // planes
  out.writeUint16(bpp);
  out.writeUint32(0); // compress
  out.writeUint32(rgbSize);
  out.writeUint32(0); // hr
  out.writeUint32(0); // vr
  out.writeUint32(0); // colors
  out.writeUint32(0); // importantColors

  for (var y = 0, pi = 0; y < image.height; ++y) {
    for (var x = 0; x < image.width; ++x, ++pi) {
      var rgba = image[pi];
      out.writeByte(getBlue(rgba));
      out.writeByte(getGreen(rgba));
      out.writeByte(getRed(rgba));
      if (bytesPerPixel == 4)
        out.writeByte(getAlpha(rgba));
    }

    // Line padding
    if (bytesPerPixel != 4) {
      var padding = 4 - ((image.width * bytesPerPixel) % 4);
      if (padding != 4) {
        out.writeBytes(List.generate(padding - 1, (index) => 0x00));

        out.writeByte(0xFF);
      }
    }
  }

  return out.getBytes();
}