SDL_GetClipRect man page

#include "SDL.h"

void SDL_GetClipRect(SDL_Surface *surface, SDL_Rect *rect);

Gets the clipping rectangle for a surface. When this surface is the destination of a blit, only the area within the clip rectangle is drawn into.

The rectangle pointed to by rect will be filled with the clipping rectangle of the surface.

SDL_SetClipRect, SDL_BlitSurface, SDL_Surface