private void EncodeGlobal <TPixel>(Image <TPixel> image, IndexedImageFrame <TPixel> quantized, int transparencyIndex, Stream stream)
where TPixel : unmanaged, IPixel <TPixel>
{
// The palette quantizer can reuse the same pixel map across multiple frames
// since the palette is unchanging. This allows a reduction of memory usage across
// multi frame gifs using a global palette.
EuclideanPixelMap <TPixel> pixelMap = default;
bool pixelMapSet = false;
for (int i = 0; i < image.Frames.Count; i++)
{
ImageFrame <TPixel> frame = image.Frames[i];
ImageFrameMetadata metadata = frame.Metadata;
GifFrameMetadata frameMetadata = metadata.GetGifMetadata();
this.WriteGraphicalControlExtension(frameMetadata, transparencyIndex, stream);
this.WriteImageDescriptor(frame, false, stream);
if (i == 0)
{
this.WriteImageData(quantized, stream);
}
else
{
if (!pixelMapSet)
{
pixelMapSet = true;
pixelMap = new EuclideanPixelMap <TPixel>(this.configuration, quantized.Palette);
}
using var paletteFrameQuantizer = new PaletteQuantizer <TPixel>(this.configuration, this.quantizer.Options, pixelMap);
using IndexedImageFrame <TPixel> paletteQuantized = paletteFrameQuantizer.QuantizeFrame(frame, frame.Bounds());
this.WriteImageData(paletteQuantized, stream);
}
}
}
