protected override void OnSave(Document input, Stream output, SaveConfigToken token, Surface scratchSurface, ProgressEventHandler progressCallback)
{
GifSaveConfigToken gsct = (GifSaveConfigToken)token;
// Flatten and pre-process the image
scratchSurface.Clear(ColorBgra.FromBgra(255, 255, 255, 0));
using (RenderArgs ra = new RenderArgs(scratchSurface))
{
input.Render(ra, true);
}
for (int y = 0; y < scratchSurface.Height; ++y)
{
unsafe
{
ColorBgra *ptr = scratchSurface.GetRowAddressUnchecked(y);
for (int x = 0; x < scratchSurface.Width; ++x)
{
if (ptr->A < gsct.Threshold)
{
ptr->Bgra = 0;
}
else
{
if (gsct.PreMultiplyAlpha)
{
int r = ((ptr->R * ptr->A) + (255 * (255 - ptr->A))) / 255;
int g = ((ptr->G * ptr->A) + (255 * (255 - ptr->A))) / 255;
int b = ((ptr->B * ptr->A) + (255 * (255 - ptr->A))) / 255;
int a = 255;
*ptr = ColorBgra.FromBgra((byte)b, (byte)g, (byte)r, (byte)a);
}
else
{
ptr->Bgra |= 0xff000000;
}
}
++ptr;
}
}
}
using (Bitmap quantized = Quantize(scratchSurface, gsct.DitherLevel, 255, progressCallback))
{
quantized.Save(output, ImageFormat.Gif);
}
}
protected GifSaveConfigToken(GifSaveConfigToken cloneMe)
{
this.threshold = cloneMe.threshold;
this.preMultiplyAlpha = cloneMe.preMultiplyAlpha;
this.ditherLevel = cloneMe.ditherLevel;
}
protected GifSaveConfigToken(GifSaveConfigToken cloneMe)
{
this.threshold = cloneMe.threshold;
this.preMultiplyAlpha = cloneMe.preMultiplyAlpha;
this.ditherLevel = cloneMe.ditherLevel;
}