Fading a 24 bit bitmap using win32
Posted on 1997-05-05
Is there a quick way to fade a 24 bit BMP from black to the original bitmap and back? My solution so far is to get the RGB values of the bitmap and scale them form 0 to x and back. Unfortunately this solution quite slow for big (say 640x480) bitmaps because of the time it takes to calculate and blit (I use SetDIBitsToDevice) the image. Is there a way to use the palette to do this (as I understand there is no real palette in 16 or 24 bit color modes)?. Or to adjust the bitmap in the videomemory directly both in 16 and 24 bit video modes? Could I use some ROP code and PatBlt to 'blend' colors? What is the fastest way? I'm using C and the win32 API.