I tried to add BGRABitmap to CSS_package but I did it badly, at least to try.
Things are drawn antialiased, but badly, seems that I did not setup the brush correctly... also it's slow because it creates and releases a bitmap each time, must be created and destroyed anywhere else only when neccessary.
bmp := TBGRABitmap.Create(TargetCanvas.Width, TargetCanvas.Height, BGRAPixelTransparent);
bmp.DrawPolygonAntialias(Ta, AColor);
bmp.Draw(ACanvas, 0, 0, False);
bmp.Free;
//TargetCanvas.Polygon(Ta);
Edit: oops, like a newby error, I created the bitmap with the size of the entire canvas each time it needs to draw
It should be replacing the ACanvas like ABGRABitmap, so instead of passing the canvas parameter in the drawing function, it must pass the BGRABitmap and draw into it, then when all the drawings are done in the TBGRABitmap, draw that to the final canvas.
In other words: the bitmap must be created only once with the size of the target canvas, then draw in the BGRABitmap object, draw to final canvas and free it.