convert method

Image convert({ Format? format, int? numChannels, num? alpha, bool withPalette = false, bool noAnimation = false, })

Convert this image to a new format or number of channels, numChannels. If the new number of channels is 4 and the current image does not have an alpha channel, then the given alpha value will be used to set the new alpha channel. If alpha is not provided, then the maxChannelValue will be used to set the alpha. If withPalette is true, and to target format and numChannels has fewer than 256 colors, then the new image will be converted to use a palette.

Implementation

Image convert(
    {Format? format,
    int? numChannels,
    num? alpha,
    bool withPalette = false,
    bool noAnimation = false}) {
  format ??= this.format;
  numChannels ??= this.numChannels;
  alpha ??= formatMaxValue[format];

  // Commented out because it causes problems converting a uint8 w/ palette
  // to a uint1 w/ palette
  /*if (withPalette &&
          (numChannels >= 4 ||
              !(format == Format.uint1 ||
                  format == Format.uint2 ||
                  format == Format.uint4 ||
                  (format == Format.uint8 && numChannels == 1))) ||
      (format.index < Format.uint8.index &&
          this.format.index >= Format.uint8.index)) {
    withPalette = false;
  }*/

  if (format == this.format &&
      numChannels == this.numChannels &&
      ((!withPalette && palette == null) ||
          (withPalette && palette != null))) {
    // Same format and number of channels
    return Image.from(this);
  }

  Image? firstFrame;
  for (final frame in frames) {
    final newImage = Image(
        width: frame.width,
        height: frame.height,
        format: format,
        numChannels: numChannels,
        withPalette: withPalette,
        exif: frame._exif?.clone(),
        iccp: frame.iccProfile?.clone(),
        backgroundColor: frame.backgroundColor?.clone(),
        frameType: frame.frameType,
        loopCount: frame.loopCount,
        frameDuration: frame.frameDuration)
      ..textData = frame.textData != null
          ? Map<String, String>.from(frame.textData!)
          : null;

    if (firstFrame != null) {
      firstFrame.addFrame(newImage);
    } else {
      firstFrame = newImage;
    }

    final pal = newImage.palette;
    final f = newImage.palette?.format ?? format;
    if (pal != null) {
      final usedColors = <int, int>{};
      var numColors = 0;
      final op = frame.getPixel(0, 0);
      Color? c;
      for (final np in newImage) {
        final nr = (op.rNormalized * 255).floor();
        final ng = (op.gNormalized * 255).floor();
        final nb = (op.bNormalized * 255).floor();
        final h = rgbaToUint32(nr, ng, nb, 0);
        if (usedColors.containsKey(h)) {
          np.index = usedColors[h]!;
        } else {
          usedColors[h] = numColors;
          np.index = numColors;
          c = convertColor(op,
              to: c, format: f, numChannels: numChannels, alpha: alpha);
          pal.setRgb(numColors, c.r, c.g, c.b);
          numColors++;
        }
        op.moveNext();
      }
    } else {
      final op = frame.getPixel(0, 0);
      for (final np in newImage) {
        convertColor(op, to: np, alpha: alpha);
        op.moveNext();
      }
    }

    if (noAnimation) {
      break;
    }
  }

  return firstFrame!;
}