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SDL_BlitSurface(3) SDL API Reference SDL_BlitSurface(3) NAME SDL_BlitSurface - This performs a fast blit from the source surface to the destination surface. SYNOPSIS #include "SDL.h" int SDL_BlitSurface(SDL_Surface *src, SDL_Rect *srcrect, SDL_Surface *dst, SDL_Rect *dstrect); DESCRIPTION This performs a fast blit from the source surface to the destination sur- face. Only the position is used in the dstrect (the width and height are ig- nored). If either srcrect or dstrect are NULL, the entire surface (src or dst) is copied. The final blit rectangle is saved in dstrect after all clipping is per- formed (srcrect is not modified). The blit function should not be called on a locked surface. The results of blitting operations vary greatly depending on whether SDL_SRCAPLHA is set or not. See SDL_SetAlpha for an explaination of how this affects your results. Colorkeying and alpha attributes also interact with surface blitting, as the following pseudo-code should hopefully ex- plain. if (source surface has SDL_SRCALPHA set) { if (source surface has alpha channel (that is, format->Amask != 0)) blit using per-pixel alpha, ignoring any colour key else { if (source surface has SDL_SRCCOLORKEY set) blit using the colour key AND the per-surface alpha value else blit using the per-surface alpha value } } else { if (source surface has SDL_SRCCOLORKEY set) blit using the colour key else ordinary opaque rectangular blit } RETURN VALUE If the blit is successful, it returns 0, otherwise it returns -1. If either of the surfaces were in video memory, and the blit returns -2, the video memory was lost, so it should be reloaded with artwork and re- blitted: while ( SDL_BlitSurface(image, imgrect, screen, dstrect) == -2 ) { while ( SDL_LockSurface(image)) < 0 ) Sleep(10); -- Write image pixels to image->pixels -- SDL_UnlockSurface(image); } This happens under DirectX 5.0 when the system switches away from your fullscreen application. Locking the surface will also fail until you have access to the video memory again. SEE ALSO SDL_LockSurface, SDL_FillRect, SDL_Surface, SDL_Rect SDL Tue 11 Sep 2001, 23:01 SDL_BlitSurface(3)
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | SEE ALSO
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