SDL_SetClipRect
From SDL Library
SDL_SetClipRect
Description
Sets the clipping rectangle for a surface. When this surface is the
destination of a blit, only the area within the clip rectangle will be
drawn into.
The rectangle pointed to by rect will be
clipped to the edges of the surface so that the clip rectangle for a
surface can never fall outside the edges of the surface.
If rect is NULL the clipping
rectangle will be set to the full size of the surface.