affecting the alpha channel with GDI functions???

[jorgander]

does anyone know how to get gdi functions (i.e. ellipse, textout, etc.) to draw to the alpha channel of a dc as well as the rgb channels? i'm already aware of the callback functionality with the LineDDA() function and that u can have your own function write to the alpha, but is it possible for anything other than a line? i even tried creating a pattern brush with a 1x1 pixel dib.

 

[palbano]

In old GDI library you would perform your drawing to a memory device context and then generate the alpha "effect" during the bitblt() to the actual device context using the raster-operation value parameter to bitblt()

-pete