Section 3: library functions
SDL_SetGammaRamp – Sets the color gamma lookup tables for the display Synopsis #include "SDL.h" int SDL_SetGammaRamp(Uint16 *redtable, Uint16 *greentable, Uint16 *bluetable); Description Sets the gamma lookup tables for the display for each color component. Each table is an array of 256 Uint16 values, representing a mapping between the input and output for that channel. The…
SDL_SetGamma – Sets the color gamma function for the display Synopsis #include "SDL.h" int SDL_SetGamma(float redgamma, float greengamma, float bluegamma); Description Sets the "gamma function" for the display of each color component. Gamma controls the brightness/contrast of colors displayed on the screen. A gamma value of 1.0 is identity (i.e., no adjustment is made). This…
SDL_SetEventFilter – Sets up a filter to process all events before they are posted to the event queue. Synopsis #include "SDL.h" void SDL_SetEventFilter(SDL_EventFilter filter); Description This function sets up a filter to process all events before they are posted to the event queue. This is a very powerful and flexible feature. The filter is prototyped…
SDL_SetCursor – Set the currently active mouse cursor. Synopsis #include "SDL.h" void SDL_SetCursor(SDL_Cursor *cursor); Description Sets the currently active cursor to the specified one. If the cursor is currently visible, the change will be immediately represented on the display. See Also SDL_GetCursor, SDL_CreateCursor, SDL_ShowCursor
SDL_SetColors – Sets a portion of the colormap for the given 8-bit surface. Synopsis #include "SDL.h" int SDL_SetColors(SDL_Surface *surface, SDL_Color *colors, int firstcolor, int ncolors); Description Sets a portion of the colormap for the given 8-bit surface. When surface is the surface associated with the current display, the display colormap will be updated with the…
SDL_SetColorKey – Sets the color key (transparent pixel) in a blittable surface and RLE acceleration. Synopsis #include "SDL.h" int SDL_SetColorKey(SDL_Surface *surface, Uint32 flag, Uint32 key); Description Sets the color key (transparent pixel) in a blittable surface and enables or disables RLE blit acceleration. RLE acceleration can substantially speed up blitting of images with large horizontal runs of…
SDL_SetClipRect – Sets the clipping rectangle for a surface. Synopsis #include "SDL.h" void SDL_SetClipRect(SDL_Surface *surface, SDL_Rect *rect); 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…
SDL_SetAlpha – Adjust the alpha properties of a surface Synopsis #include "SDL.h" int SDL_SetAlpha(SDL_Surface *surface, Uint32 flag, Uint8 alpha); Description Note: This function and the semantics of SDL alpha blending have changed since version 1.1.4. Up until version 1.1.5, an alpha value of 0 was considered opaque and a value of 255 was considered transparent….
SDL_SemWaitTimeout – Lock a semaphore, but only wait up to a specified maximum time. Synopsis #include "SDL.h" #include "SDL_thread.h" int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout); Description SDL_SemWaitTimeout() is a varient of SDL_SemWait with a maximum timeout value. If the value of the semaphore pointed to by sem is positive (greater than zero) it will atomically decrement…
SDL_SemWait – Lock a semaphore and suspend the thread if the semaphore value is zero. Synopsis #include "SDL.h" #include "SDL_thread.h" int SDL_SemWait(SDL_sem *sem); Description SDL_SemWait() suspends the calling thread until either the semaphore pointed to by sem has a positive value, the call is interrupted by a signal or error. If the call is successful…
SDL_SemValue – Return the current value of a semaphore. Synopsis #include "SDL.h" #include "SDL/SDL_thread.h" Uint32 SDL_SemValue(SDL_sem *sem); Description SDL_SemValue() returns the current semaphore value from the semaphore pointed to by sem. Return Value Returns current value of the semaphore. Examples sem_value = SDL_SemValue(my_sem); See Also SDL_CreateSemaphore, SDL_DestroySemaphore, SDL_SemWait, SDL_SemTryWait, SDL_SemWaitTimeout, SDL_SemPost
SDL_SemTryWait – Attempt to lock a semaphore but don’t suspend the thread. Synopsis #include "SDL.h" #include "SDL_thread.h" int SDL_SemTryWait(SDL_sem *sem); Description SDL_SemTryWait is a non-blocking varient of SDL_SemWait. If the value of the semaphore pointed to by sem is positive it will atomically decrement the semaphore value and return 0, otherwise it will return SDL_MUTEX_TIMEOUT…
SDL_SemPost – Unlock a semaphore. Synopsis #include "SDL.h" #include "SDL_thread.h" int SDL_SemPost(SDL_sem *sem); Description SDL_SemPost unlocks the semaphore pointed to by sem and atomically increments the semaphores value. Threads that were blocking on the semaphore may be scheduled after this call succeeds. SDL_SemPost should be called after a semaphore is locked by a successful call…
SDL_Rect – Defines a rectangular area Structure Definition typedef struct{ Sint16 x, y; Uint16 w, h; } SDL_Rect; Structure Data x, y Position of the upper-left corner of the rectangle w, h The width and height of the rectangle Description A SDL_Rect defines a rectangular area of pixels. It is used by SDL_BlitSurface to define…
SDL_FunctionName – Short description of function Synopsis #include "SDL.h" return typeSDL_FunctionName(parameter); Description Full description Examples examples here See Also SDL_AnotherFunction
SDL_QuitSubSystem – Shut down a subsystem Synopsis #include "SDL.h" void SDL_QuitSubSystem(Uint32 flags); Description SDL_QuitSubSystem allows you to shut down a subsystem that has been previously initialized by SDL_Init or SDL_InitSubSystem. The flags tells SDL_QuitSubSystem which subsystems to shut down, it uses the same values that are passed to SDL_Init. See Also SDL_Quit, SDL_Init, SDL_InitSubSystem
SDL_QuitEvent – Quit requested event Structure Definition typedef struct{ Uint8 type } SDL_QuitEvent; Structure Data type SDL_QUIT Description SDL_QuitEvent is a member of the SDL_Event union and is used whan an event of type SDL_QUIT is reported. As can be seen, the SDL_QuitEvent structure serves no useful purpose. The event itself, on the other hand,…
SDL_Quit – Shut down SDL Synopsis #include "SDL.h" void SDL_Quit(void); Description SDL_Quit shuts down all SDL subsystems and frees the resources allocated to them. This should always be called before you exit. For the sake of simplicity you can set SDL_Quit as your atexit call, like: SDL_Init(SDL_INIT_VIDEO|SDL_INIT_AUDIO); atexit(SDL_Quit); . . Note: While using atexit maybe…
SDL_PushEvent – Pushes an event onto the event queue Synopsis #include "SDL.h" int SDL_PushEvent(SDL_Event *event); Description The event queue can actually be used as a two way communication channel. Not only can events be read from the queue, but the user can also push their own events onto it. event is a pointer to the…
SDL_PumpEvents – Pumps the event loop, gathering events from the input devices. Synopsis #include "SDL.h" void SDL_PumpEvents(void); Description Pumps the event loop, gathering events from the input devices. SDL_PumpEvents gathers all the pending input information from devices and places it on the event queue. Without calls to SDL_PumpEvents no events would ever be placed on…