SDL_LockSurface man page on JazzOS

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SDL_LockSurface(3)	       SDL API Reference	    SDL_LockSurface(3)

       SDL_LockSurface - Lock a surface for directly access.

       #include "SDL.h"

       int SDL_LockSurface(SDL_Surface *surface);

       SDL_LockSurface	sets  up  a surface for directly accessing the pixels.
       Between calls to SDL_LockSurface and SDL_UnlockSurface, you  can	 write
       to and read from surface->pixels, using the pixel format stored in sur‐
       face->format. Once you are done accessing the surface, you  should  use
       SDL_UnlockSurface to release it.

       Not all surfaces require locking. If SDL_MUSTLOCK(surface) evaluates to
       0, then you can read and write to the surface  at  any  time,  and  the
       pixel format of the surface will not change.

       No operating system or library calls should be made between lock/unlock
       pairs, as critical system locks may be held during this time.

       It should be noted, that since SDL 1.1.8 surface locks  are  recursive.
       This  means  that  you can lock a surface multiple times, but each lock
       must have a match unlock.

	   SDL_LockSurface( surface );
	   /* Surface is locked */
	   /* Direct pixel access on surface here */
	   SDL_LockSurface( surface );
	   /* More direct pixel access on surface */
	   SDL_UnlockSurface( surface );
	   /* Surface is still locked */
	   /* Note: Is versions < 1.1.8, the surface would have been */
	   /* no longer locked at this stage			     */
	   SDL_UnlockSurface( surface );
	   /* Surface is now unlocked */

       SDL_LockSurface returns 0, or -1 if the surface couldn't be locked.


SDL			    Tue 11 Sep 2001, 23:01	    SDL_LockSurface(3)

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