====== (This is the legacy documentation for stable SDL2, the current stable version; [https://wiki.libsdl.org/SDL3/ SDL3] is the current development version.) ====== = SDL_PremultiplyAlpha = Premultiply the alpha on a block of pixels. == Syntax == int SDL_PremultiplyAlpha(int width, int height, Uint32 src_format, const void * src, int src_pitch, Uint32 dst_format, void * dst, int dst_pitch); == Function Parameters == {| |'''width''' |the width of the block to convert, in pixels |- |'''height''' |the height of the block to convert, in pixels |- |'''src_format''' |an [[SDL_PixelFormatEnum]] value of the src pixels format |- |'''src''' |a pointer to the source pixels |- |'''src_pitch''' |the pitch of the source pixels, in bytes |- |'''dst_format''' |an [[SDL_PixelFormatEnum]] value of the dst pixels format |- |'''dst''' |a pointer to be filled in with premultiplied pixel data |- |'''dst_pitch''' |the pitch of the destination pixels, in bytes |} == Return Value == Returns 0 on success or a negative error code on failure; call [[SDL_GetError]]() for more information. == Remarks == This is safe to use with src == dst, but not for other overlapping areas. This function is currently only implemented for [[SDL_PIXELFORMAT_ARGB8888]]. == Version == This function is available since SDL 2.0.18. ---- [[CategoryAPI]]