Fixed alpha composition when destination alpha is transparent. Jianyu Guan I found I make a big mistake that when dstA==0, I just simply let *dstp=*srcp and forgot to make dstRGB = srcRGB*srcA. The if consition "(*dstp & amask) == 0" in BlitRGBtoRGBPixelAlphaMMX and BlitRGBtoRGBPixelAlphaMMX3dNow should be removed.