[SDL] Extra bytes at the end of rows on surfaces

[Christian Walther]

Mike Powell wrote:
> 
> uint32 srcPixel =
> *(uint32*)((uint8*)surf->pixels+(i*surf->format->BytesPerPixel));
> 
> ...
> 
> However, I remain rather confused why this extra byte is appearing
> there. I've used SDL_Image to load images for a lot of projects in
> the past, and I've experienced this padding before. Does anybody know
> what could cause that?

Usually rows are padded to a multiple of 4 bytes because 4-byte-aligned 
stuff is what the usual 32-bit processors can access most efficiently. 
But don't rely on that number, rows may be padded to any length. The 
proper way to deal with this is to use the "pitch" field: Pixel (x,y) is 
located at (Uint8*)surf->pixels + y*surf->pitch + 
x*surf->format->bytesPerPixel.

  -Christian