Re: 8 bit pixel in memory blits

"todd" <timza1221-/[email protected]> wrote:
> Does anyone know if 8 bit per pixel StretchDIBits() blits can be done 
> in-memory?
> Is a palette required for the bitmaps and if so is SelectPalette() 
> required?
> Having trouble maintaining the 8-bit (gray scale) colors.

What exactly are you trying to do? Stretch an 8bpp DIB into another? 
StretchDIBits can do this without palettes if you specify DIB_RGB_COLORS and 
fill in the bmiColors array in the BITMAPINFO structure. The destination DC 
should contain a bitmap created with CreateDIBSection, again specifying 
DIB_RGB_COLORS and a valid bmiColors array.

You should call SetStretchBltMode(STRETCH_DELETESCANS) for the destination 
DC - the default is STRETCH_ANDSCANS which causes strange results when 
shrinking. Note that StretchDIBits is only capable of a very low-quality 
"pixel resize". For anything better, e.g. interpolation or pixel averaging, 
you'd need to use something other than StretchDIBits.

- Jim 



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