I am using DirectFB-0.9.22 on Linux nVidia(NV32) Framebuffer support(kernel 2.6.13).
On a surface with
PorterDuff rule set as DSPD_SRC,
DrawingFlags set to DSDRAW_BLEND, and
pixelformat set to DSPF_ARGB
I don't see any BLEND effect with varying alpha component of color. For example if I do a SetColor with red = 0xff and alpha = 1, and do a FillRectangle I see a solid red rectangle. The effect is same as alpha = 0xff.
I observe a change in behavior when I OR the DrawingFlags with DSDRAW_SRC_PREMULTIPLY. Then I can see the blend.
Shouldn't the alpha component change impact the drawing without DSDRAW_SRC_PREMULTIPLY flag? Because DSDRAW_SRC_PREMULTIPLY forces a change in red, green, blue components and thus the effect is seen. Changing alpha component alone should make a visible difference, isn't it?
Am I missing something obvious here? Or could this be a problem with the Framebuffer support/driver?
Thanks in advance!
-- Sourath
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