Premultiplied alpha handle for driver

[Huang, FrankR]

Hi all,

 

            A question to ask.

            We know the premultiplied alpha will be used sometimes in
blend. Is that used in the graphics driver?

            Take an example:

                        If we use a XRenderComposite() function to do
the rendering:

                                   XRenderComposite(dyp, PictOpOver,
picture_1x1[0].pict, mask_20x20[0].pict, win->pict, 0, 0, 0, 0, 50, 50,
40, 40);

                                    And the picture_1x1[0] is a ARGB
picture with an alpha value; mask_20x20[0] is a A8 picture with an alpha
value.

                        How the driver(do_composite) handle this two
alpha value?

 

 

Thanks,

Frank

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