public Color32[] GeneratePalette(IAsyncContext context)
{
// Occurs when bitmap is completely transparent
if (root.Count == 0)
{
Debug.Assert(hasTransparency);
return(new Color32[1]);
}
Color32[] result;
if (root.IsSingleColor)
{
result = new Color32[hasTransparency ? 2 : 1];
result[0] = root.ToColor();
return(result);
}
context.Progress?.New(DrawingOperation.GeneratingPalette, MaxActualColors, 1);
var buckets = new ColorBucketCollection(MaxActualColors);
buckets.AddBucket(root);
// splitting the initial bucket until no more split can be done or desired color amount is reached
int startIndex = 0;
while (buckets.ColorsCount < MaxActualColors)
{
if (buckets.SplitBuckets(context, ref startIndex))
{
startIndex = 0;
}
else
{
break;
}
}
// finalizing colors and continuing splitting if some buckets map to the same colors
while (buckets.FinalColorsCount < MaxActualColors)
{
ColorBucket first = buckets.RemoveFirstBucket();
if (first == null)
{
break;
}
if (startIndex > 0)
{
startIndex -= 1;
}
if (!buckets.AddFinalColor(first.ToColor()))
{
buckets.SplitBuckets(context, ref startIndex);
}
}
if (context.IsCancellationRequested)
{
return(null);
}
Debug.Assert(buckets.FinalColorsCount <= MaxActualColors);
result = new Color32[buckets.FinalColorsCount + (hasTransparency ? 1 : 0)];
buckets.CopyFinalColorsTo(result);
context.Progress?.Complete();
// If transparent color is needed, then it will be automatically the last color in the result
return(result);
}
