WhatsNew
author Sam Lantinga <slouken@libsdl.org>
Sun, 04 Jan 2004 15:18:08 +0000
changeset 764 974c0fb74bf8
parent 751 6e9505e0647f
child 781 67176351a1b8
permissions -rw-r--r--
Added function to create RWops from const memory: SDL_RWFromConstMem()
     1 
     2 This is a list of API changes in SDL's version history.
     3 
     4 Version 1.0:
     5 
     6 1.2.7:
     7 	Added CPU feature detection functions to SDL_cpuinfo.h:
     8 		SDL_HasRDTSC(), SDL_HasMMX(), SDL_Has3DNow(), SDL_HasSSE()
     9 	Added function to create RWops from const memory: SDL_RWFromConstMem()
    10 
    11 1.2.6:
    12 	Added SDL_LoadObject(), SDL_LoadFunction(), and SDL_UnloadObject()
    13 
    14 	Added SDL_GL_MULTISAMPLEBUFFERS and SDL_GL_MULTISAMPLESAMPLES for FSAA
    15 
    16 1.2.5:
    17 	Added SDL_BUTTON_WHEELUP (4) and SDL_BUTTON_WHEELDOWN (5)
    18 
    19 	Added SDL_GL_STEREO for stereoscopic OpenGL contexts
    20 
    21 1.2.0:
    22 	Added SDL_VIDEOEXPOSE event to signal that the screen needs to
    23 	be redrawn.  This is currently only delivered to OpenGL windows
    24 	on X11, though it may be delivered in the future when the video
    25 	memory is lost under DirectX.
    26 
    27 1.1.8:
    28 	You can pass SDL_NOFRAME to SDL_VideoMode() to create a window
    29 	that has no title bar or frame decoration.  Fullscreen video
    30 	modes automatically have this flag set.
    31 
    32 	Added a function to query the clipping rectangle for a surface:
    33 		void SDL_GetClipRect(SDL_Surface *surface, SDL_Rect *rect)
    34 
    35 	Added a function to query the current event filter:
    36 		SDL_EventFilter SDL_GetEventFilter(void)
    37 
    38 	If you pass -1 to SDL_ShowCursor(), it won't change the current
    39 	cursor visibility state, but will still return it.
    40 
    41 	SDL_LockSurface() and SDL_UnlockSurface() are recursive, meaning
    42 	you can nest them as deep as you want, as long as each lock call
    43 	has a matching unlock call.  The surface remains locked until the
    44 	last matching unlock call.
    45 
    46 	Note that you may not blit to or from a locked surface.
    47 
    48 1.1.7:
    49 	The SDL_SetGammaRamp() and SDL_GetGammaRamp() functions now take
    50 	arrays of Uint16 values instead of Uint8 values.  For the most part,
    51 	you can just take your old values and shift them up 8 bits to get
    52 	new correct values for your gamma ramps.
    53 
    54 	You can pass SDL_RLEACCEL in flags passed to SDL_ConvertSurface()
    55         and SDL will try to RLE accelerate colorkey and alpha blits in the
    56 	resulting surface.
    57 
    58 1.1.6:
    59 	Added a function to return the thread ID of a specific thread:
    60 		Uint32 SDL_GetThreadID(SDL_Thread *thread)
    61 	If 'thread' is NULL, this function returns the id for this thread.
    62 
    63 1.1.5:
    64 	The YUV overlay structure has been changed to use an array of
    65 	pitches and pixels representing the planes of a YUV image, to
    66 	better enable hardware acceleration.  The YV12 and IYUV formats
    67 	each have three planes, corresponding to the Y, U, and V portions
    68 	of the image, while packed pixel YUV formats just have one plane.
    69 
    70 	For palettized mode (8bpp), the screen colormap is now split in
    71 	a physical and a logical palette. The physical palette determines
    72 	what colours the screen pixels will get when displayed, and the
    73 	logical palette controls the mapping from blits to/from the screen.
    74 	A new function, SDL_SetPalette() has been added to change
    75 	logical and physical palettes separately. SDL_SetColors() works
    76 	just as before, and is equivalent to calling SDL_SetPalette() with
    77 	a flag argument of (SDL_LOGPAL|SDL_PHYSPAL).
    78 
    79 	SDL_BlitSurface() no longer modifies the source rectangle, only the
    80 	destination rectangle. The width/height members of the destination
    81 	rectangle are ignored, only the position is used.
    82 
    83 	The old source clipping function SDL_SetClipping() has been replaced
    84 	with a more useful function to set the destination clipping rectangle:
    85 		SDL_bool SDL_SetClipRect(SDL_Surface *surface, SDL_Rect *rect)
    86 		
    87 	Added a function to see what subsystems have been initialized:
    88 		Uint32 SDL_WasInit(Uint32 flags)
    89 
    90 	The Big Alpha Flip: SDL now treats alpha as opacity like everybody
    91 	else, and not as transparency:
    92 
    93 	A new cpp symbol: SDL_ALPHA_OPAQUE is defined as 255
    94 	A new cpp symbol: SDL_ALPHA_TRANSPARENT is defined as 0
    95 	Values between 0 and 255 vary from fully transparent to fully opaque.
    96 
    97 	New functions:
    98 	SDL_DisplayFormatAlpha()
    99 	    Returns a surface converted to a format with alpha-channel
   100 	    that can be blit efficiently to the screen. (In other words,
   101 	    like SDL_DisplayFormat() but the resulting surface has
   102 	    an alpha channel.)  This is useful for surfaces with alpha.
   103 	SDL_MapRGBA()
   104 	    Works as SDL_MapRGB() but takes an additional alpha parameter.
   105 	SDL_GetRGBA()
   106 	    Works as SDL_GetRGB() but also returns the alpha value
   107 	    (SDL_ALPHA_OPAQUE for formats without an alpha channel)
   108 
   109 	Both SDL_GetRGB() and SDL_GetRGBA() now always return values in
   110 	the [0..255] interval. Previously, SDL_GetRGB() would return
   111 	(0xf8, 0xfc, 0xf8) for a completely white pixel in RGB565 format.
   112 	(N.B.: This is broken for bit fields < 3 bits.)
   113 
   114 	SDL_MapRGB() returns pixels in which the alpha channel is set opaque.
   115 
   116 	SDL_SetAlpha() can now be used for both setting the per-surface
   117 	alpha, using the new way of thinking of alpha, and also to enable
   118 	and disable per-pixel alpha blending for surfaces with an alpha
   119 	channel:
   120 		To disable alpha blending:
   121 			SDL_SetAlpha(surface, 0, 0);
   122 		To re-enable alpha blending:
   123 			SDL_SetAlpha(surface, SDL_SRCALPHA, 0);
   124 	Surfaces with an alpha channel have blending enabled by default.
   125 
   126 	SDL_SetAlpha() now accepts SDL_RLEACCEL as a flag, which requests
   127 	RLE acceleration of blits, just as like with SDL_SetColorKey().
   128 	This flag can be set for both surfaces with an alpha channel
   129 	and surfaces with an alpha value set by SDL_SetAlpha().
   130 	As always, RLE surfaces must be locked before pixel access is
   131 	allowed, and unlocked before any other SDL operations are done
   132 	on it.
   133 
   134 	The blit semantics for surfaces with and without alpha and colorkey
   135 	have now been defined:
   136 
   137 	RGBA->RGB:
   138 	    SDL_SRCALPHA set:
   139 		alpha-blend (using alpha-channel).
   140 		SDL_SRCCOLORKEY ignored.
   141 	    SDL_SRCALPHA not set:
   142 		copy RGB.
   143 		if SDL_SRCCOLORKEY set, only copy the pixels matching the
   144 		RGB values of the source colour key, ignoring alpha in the
   145 		comparison.
   146 
   147 	RGB->RGBA:
   148 	    SDL_SRCALPHA set:
   149 		alpha-blend (using the source per-surface alpha value);
   150 		set destination alpha to opaque.
   151 	    SDL_SRCALPHA not set:
   152 		copy RGB, set destination alpha to opaque.
   153 	    both:
   154 		if SDL_SRCCOLORKEY set, only copy the pixels matching the
   155 		source colour key.
   156 
   157 	RGBA->RGBA:
   158 	    SDL_SRCALPHA set:
   159 		alpha-blend (using the source alpha channel) the RGB values;
   160 		leave destination alpha untouched. [Note: is this correct?]
   161 		SDL_SRCCOLORKEY ignored.
   162 	    SDL_SRCALPHA not set:
   163 		copy all of RGBA to the destination.
   164 		if SDL_SRCCOLORKEY set, only copy the pixels matching the
   165 		RGB values of the source colour key, ignoring alpha in the
   166 		comparison.
   167 
   168 	RGB->RGB: 
   169 	    SDL_SRCALPHA set:
   170 		alpha-blend (using the source per-surface alpha value).
   171 	    SDL_SRCALPHA not set:
   172 		copy RGB.
   173 	    both:
   174 		if SDL_SRCCOLORKEY set, only copy the pixels matching the
   175 		source colour key.
   176 
   177 	As a special case, blits from surfaces with per-surface alpha
   178 	value of 128 (50% transparency) are optimised and much faster
   179 	than other alpha values. This does not apply to surfaces with
   180 	alpha channels (per-pixel alpha).
   181 
   182 	New functions for manipulating the gamma of the display have
   183 	been added:
   184 		int SDL_SetGamma(float red, float green, float blue);
   185 		int SDL_SetGammaRamp(Uint8 *red, Uint8 *green, Uint8 *blue);
   186 		int SDL_GetGammaRamp(Uint8 *red, Uint8 *green, Uint8 *blue);
   187 	Gamma ramps are tables with 256 entries which map the screen color
   188 	components into actually displayed colors.  For an example of
   189 	implementing gamma correction and gamma fades, see test/testgamma.c
   190 	Gamma control is not supported on all hardware.
   191 
   192 1.1.4:
   193 	The size of the SDL_CDtrack structure changed from 8 to 12 bytes
   194 	as the size of the length member was extended to 32 bits.
   195 
   196         You can now use SDL for 2D blitting with a GL mode by passing the
   197 	SDL_OPENGLBLIT flag to SDL_SetVideoMode().  You can specify 16 or
   198 	32 bpp, and the data in the framebuffer is put into the GL scene
   199 	when you call SDL_UpdateRects(), and the scene will be visible
   200 	when you call SDL_GL_SwapBuffers().
   201 
   202 	Run the "testgl" test program with the -logo command line option
   203 	to see an example of this blending of 2D and 3D in SDL.
   204 
   205 1.1.3:
   206 	Added SDL_FreeRW() to the API, to complement SDL_AllocRW()
   207 
   208 	Added resizable window support - just add SDL_RESIZABLE to the
   209 	SDL_SetVideoMode() flags, and then wait for SDL_VIDEORESIZE events.
   210 	See SDL_events.h for details on the new SDL_ResizeEvent structure.
   211 
   212 	Added condition variable support, based on mutexes and semaphores.
   213 		SDL_CreateCond()
   214 		SDL_DestroyCond()
   215 		SDL_CondSignal()
   216 		SDL_CondBroadcast()
   217 		SDL_CondWait()
   218 		SDL_CondTimedWait()
   219 	The new function prototypes are in SDL_mutex.h
   220 
   221 	Added counting semaphore support, based on the mutex primitive.
   222 		SDL_CreateSemaphore()
   223 		SDL_DestroySemaphore()
   224 		SDL_SemWait()
   225 		SDL_SemTryWait()
   226 		SDL_SemWaitTimeout()
   227 		SDL_SemPost()
   228 		SDL_SemValue()
   229 	The new function prototypes are in SDL_mutex.h
   230 
   231 	Added support for asynchronous blitting.  To take advantage of this,
   232 	you must set the SDL_ASYNCBLIT flag when setting the video mode and
   233 	creating surfaces that you want accelerated in this way.  You must
   234 	lock surfaces that have this flag set, and the lock will block until
   235 	any queued blits have completed.
   236 
   237 	Added YUV video overlay support.
   238 	The supported YUV formats are: YV12, IYUV, YUY2, UYVY, and YVYU.
   239 	This function creates an overlay surface:
   240 		SDL_CreateYUVOverlay()
   241 	You must lock and unlock the overlay to get access to the data:
   242 		SDL_LockYUVOverlay() SDL_UnlockYUVOverlay()
   243 	You can then display the overlay:
   244 		SDL_DisplayYUVOverlay()
   245 	You must free the overlay when you are done using it:
   246 		SDL_FreeYUVOverlay()
   247 	See SDL_video.h for the full function prototypes.
   248 
   249 	The joystick hat position constants have been changed:
   250 	Old constant            New constant
   251 	------------            ------------
   252 	     0                  SDL_HAT_CENTERED
   253 	     1                  SDL_HAT_UP
   254 	     2                  SDL_HAT_RIGHTUP
   255 	     3                  SDL_HAT_RIGHT
   256 	     4                  SDL_HAT_RIGHTDOWN
   257 	     5                  SDL_HAT_DOWN
   258 	     6                  SDL_HAT_LEFTDOWN
   259 	     7                  SDL_HAT_LEFT
   260 	     8                  SDL_HAT_LEFTUP
   261 	The new constants are bitmasks, so you can check for the
   262 	individual axes like this:
   263 		if ( hat_position & SDL_HAT_UP ) {
   264 		}
   265 	and you'll catch left-up, up, and right-up.
   266 
   267 1.1.2:
   268 	Added multiple timer support:
   269 		SDL_AddTimer() and SDL_RemoveTimer()
   270 
   271 	SDL_WM_SetIcon() now respects the icon colorkey if mask is NULL.
   272 
   273 1.1.0:
   274 	Added initial OpenGL support.
   275 	First set GL attributes (such as RGB depth, alpha depth, etc.)
   276 		SDL_GL_SetAttribute()
   277 	Then call SDL_SetVideoMode() with the SDL_OPENGL flag.
   278 	Perform all of your normal GL drawing.
   279 	Finally swap the buffers with the new SDL function:
   280 		SDL_GL_SwapBuffers()
   281 	See the new 'testgl' test program for an example of using GL with SDL.
   282 
   283 	You can load GL extension functions by using the function:
   284 		SDL_GL_LoadProcAddress()
   285 
   286 	Added functions to initialize and cleanup specific SDL subsystems:
   287 		SDL_InitSubSystem() and SDL_QuitSubSystem()
   288 
   289 	Added user-defined event type:
   290 		typedef struct {
   291         		Uint8 type;
   292         		int code;
   293         		void *data1;
   294         		void *data2;
   295 		} SDL_UserEvent;
   296 	This structure is in the "user" member of an SDL_Event.
   297 
   298 	Added a function to push events into the event queue:
   299 		SDL_PushEvent()
   300 
   301 	Example of using the new SDL user-defined events:
   302 	{
   303 		SDL_Event event;
   304 
   305 		event.type = SDL_USEREVENT;
   306 		event.user.code = my_event_code;
   307 		event.user.data1 = significant_data;
   308 		event.user.data2 = 0;
   309 		SDL_PushEvent(&event);
   310 	}
   311 
   312 	Added a function to get mouse deltas since last query:
   313 		SDL_GetRelativeMouseState()
   314 
   315 	Added a boolean datatype to SDL_types.h:
   316 		SDL_bool = { SDL_TRUE, SDL_FALSE }
   317 
   318 	Added a function to get the current audio status:
   319 		SDL_GetAudioState();
   320 	It returns one of:
   321 		SDL_AUDIO_STOPPED,
   322 		SDL_AUDIO_PLAYING,
   323 		SDL_AUDIO_PAUSED
   324 
   325 	Added an AAlib driver (ASCII Art) - by Stephane Peter.
   326 
   327 1.0.6:
   328 	The input grab state is reset after each call to SDL_SetVideoMode().
   329 	The input is grabbed by default in fullscreen mode, and ungrabbed in
   330 	windowed mode.  If you want to set input grab to a particular value,
   331 	you should set it after each call to SDL_SetVideoMode().
   332 
   333 1.0.5:
   334 	Exposed SDL_AudioInit(), SDL_VideoInit()
   335 	Added SDL_AudioDriverName() and SDL_VideoDriverName()
   336 
   337 	Added new window manager function:
   338 		SDL_WM_ToggleFullScreen()
   339 	This is currently implemented only on Linux
   340 
   341 	The ALT-ENTER code has been removed - it's not appropriate for a
   342 	lib to bind keys when they aren't even emergency escape sequences.
   343 
   344 	ALT-ENTER functionality can be implemented with the following code:
   345 
   346 	int Handle_AltEnter(const SDL_Event *event)
   347 	{
   348 	    if ( event->type == SDL_KEYDOWN ) {
   349 	        if ( (event->key.keysym.sym == SDLK_RETURN) &&
   350 	             (event->key.keysym.mod & KMOD_ALT) ) {   
   351 	                SDL_WM_ToggleFullScreen(SDL_GetVideoSurface());
   352 	                return(0);
   353 	        }
   354 	    }
   355 	    return(1);
   356 	}
   357 	SDL_SetEventFilter(Handle_AltEnter);
   358 
   359 1.0.3:
   360 	Under X11, if you grab the input and hide the mouse cursor,
   361 	the mouse will go into a "relative motion" mode where you
   362 	will always get relative motion events no matter how far in
   363 	each direction you move the mouse - relative motion is not
   364 	bounded by the edges of the window (though the absolute values
   365 	of the mouse positions are clamped by the size of the window).
   366 	The SVGAlib, framebuffer console, and DirectInput drivers all
   367 	have this behavior naturally, and the GDI and BWindow drivers
   368 	never go into "relative motion" mode.
   369 
   370 1.0.2:
   371 	Added a function to enable keyboard repeat:
   372 		SDL_EnableKeyRepeat()
   373 
   374 	Added a function to grab the mouse and keyboard input
   375 		SDL_WM_GrabInput()
   376 
   377 	Added a function to iconify the window.
   378 		SDL_WM_IconifyWindow()
   379 	If this function succeeds, the application will receive an event
   380 	signaling SDL_APPACTIVE event 
   381 
   382 1.0.1:
   383 	Added constants to SDL_audio.h for 16-bit native byte ordering:
   384 		AUDIO_U16SYS, AUDIO_S16SYS
   385 
   386 1.0.0:
   387 	New public release
   388 
   389 Version 0.11:
   390 
   391 0.11.5:
   392 	A new function SDL_GetVideoSurface() has been added, and returns
   393 	a pointer to the current display surface.
   394 
   395 	SDL_AllocSurface() has been renamed SDL_CreateRGBSurface(), and
   396 	a new function SDL_CreateRGBSurfaceFrom() has been added to allow
   397 	creating an SDL surface from an existing pixel data buffer.
   398 
   399 	Added SDL_GetRGB() to the headers and documentation.
   400 
   401 0.11.4:
   402 	SDL_SetLibraryPath() is no longer meaningful, and has been removed.
   403 
   404 0.11.3:
   405 	A new flag for SDL_Init(), SDL_INIT_NOPARACHUTE, prevents SDL from
   406 	installing fatal signal handlers on operating systems that support
   407 	them.
   408 
   409 Version 0.9:
   410 
   411 0.9.15:
   412 	SDL_CreateColorCursor() has been removed.  Color cursors should
   413 	be implemented as sprites, blitted by the application when the
   414 	cursor moves.  To get smooth color cursor updates when the app
   415 	is busy, pass the SDL_INIT_EVENTTHREAD flag to SDL_Init().  This
   416 	allows you to handle the mouse motion in another thread from an
   417 	event filter function, but is currently only supported by Linux
   418 	and BeOS.  Note that you'll have to protect the display surface
   419 	from multi-threaded access by using mutexes if you do this.
   420 
   421 	Thread-safe surface support has been removed from SDL.
   422 	This makes blitting somewhat faster, by removing SDL_MiddleBlit().
   423 	Code that used SDL_MiddleBlit() should use SDL_LowerBlit() instead.
   424 	You can make your surfaces thread-safe by allocating your own
   425 	mutex and making lock/unlock calls around accesses to your surface.
   426 
   427 0.9.14:
   428 	SDL_GetMouseState() now takes pointers to int rather than Uint16.
   429 
   430 	If you set the SDL_WINDOWID environment variable under UNIX X11,
   431 	SDL will use that as the main window instead of creating it's own.
   432 	This is an unsupported extension to SDL, and not portable at all.
   433 
   434 0.9.13:
   435 	Added a function SDL_SetLibraryPath() which can be used to specify
   436 	the directory containing the SDL dynamic libraries.  This is useful
   437 	for commercial applications which ship with particular versions
   438 	of the libraries, and for security on multi-user systems.
   439 	If this function is not used, the default system directories are 
   440 	searched using the native dynamic object loading mechanism.
   441 
   442 	In order to support C linkage under Visual C++, you must declare
   443 	main() without any return type:
   444 		main(int argc, char *argv[]) {
   445 			/* Do the program... */
   446 			return(0);
   447 		}
   448 	C++ programs should also return a value if compiled under VC++.
   449 
   450 	The blit_endian member of the SDL_VideoInfo struct has been removed.
   451 
   452 	SDL_SymToASCII() has been replaced with SDL_GetKeyName(), so there
   453 	is now no longer any function to translate a keysym to a character.
   454 
   455 	The SDL_keysym structure has been extended with a 'scancode' and
   456 	'unicode' member.  The 'scancode' is a hardware specific scancode
   457 	for the key that was pressed, and may be 0.  The 'unicode' member
   458 	is a 16-bit UNICODE translation of the key that was pressed along
   459 	with any modifiers or compose keys that have been pressed.
   460 	If no UNICODE translation exists for the key, 'unicode' will be 0.
   461 
   462 	Added a function SDL_EnableUNICODE() to enable/disable UNICODE
   463 	translation of character keypresses.  Translation defaults off.
   464 
   465 	To convert existing code to use the new API, change code which
   466 	uses SDL_SymToASCII() to get the keyname to use SDL_GetKeyName(),
   467 	and change code which uses it to get the ASCII value of a sym to
   468 	use the 'unicode' member of the event keysym.
   469 
   470 0.9.12:
   471 	There is partial support for 64-bit datatypes.  I don't recommend 
   472 	you use this if you have a choice, because 64-bit datatypes are not
   473 	supported on many platforms.  On platforms for which it is supported,
   474 	the SDL_HAS_64BIT_TYPE C preprocessor define will be enabled, and
   475 	you can use the Uint64 and Sint64 datatypes.
   476 
   477 	Added functions to SDL_endian.h to support 64-bit datatypes:
   478 	    SDL_SwapLE64(), SDL_SwapBE64(),
   479 	    SDL_ReadLE64(), SDL_ReadBE64(), SDL_WriteLE64(), SDL_WriteBE64()
   480 
   481 	A new member "len_ratio" has been added to the SDL_AudioCVT structure,
   482 	and allows you to determine either the original buffer length or the
   483 	converted buffer length, given the other.
   484 
   485 	A new function SDL_FreeWAV() has been added to the API to free data
   486 	allocated by SDL_LoadWAV_RW().  This is necessary under Win32 since
   487 	the gcc compiled DLL uses a different heap than VC++ compiled apps.
   488 
   489 	SDL now has initial support for international keyboards using the
   490 	Latin character set.
   491 	If a particular mapping is desired, you can set the DEFAULT_KEYBOARD
   492 	compile-time variable, or you can set the environment variable 
   493 	"SDL_KEYBOARD" to a string identifying the keyboard mapping you desire.
   494 	The valid values for these variables can be found in SDL_keyboard.c
   495 
   496 	Full support for German and French keyboards under X11 is implemented.
   497 
   498 0.9.11:
   499 	The THREADED_EVENTS compile-time define has been replaced with the
   500 	SDL_INIT_EVENTTHREAD flag.  If this flag is passed to SDL_Init(),
   501 	SDL will create a separate thread to perform input event handling.
   502 	If this flag is passed to SDL_Init(), and the OS doesn't support 
   503 	event handling in a separate thread, SDL_Init() will fail.
   504 	Be sure to add calls to SDL_Delay() in your main thread to allow
   505 	the OS to schedule your event thread, or it may starve, leading
   506 	to slow event delivery and/or dropped events.
   507 	Currently MacOS and Win32 do not support this flag, while BeOS 
   508 	and Linux do support it.  I recommend that your application only
   509 	use this flag if absolutely necessary.
   510 
   511 	The SDL thread function passed to SDL_CreateThread() now returns a
   512 	status.  This status can be retrieved by passing a non-NULL pointer
   513 	as the 'status' argument to SDL_WaitThread().
   514 
   515 	The volume parameter to SDL_MixAudio() has been increased in range
   516 	from (0-8) to (0-128)
   517 
   518 	SDL now has a data source abstraction which can encompass a file,
   519 	an area of memory, or any custom object you can envision.  It uses
   520 	these abstractions, SDL_RWops, in the endian read/write functions,
   521 	and the built-in WAV and BMP file loaders.  This means you can load
   522 	WAV chunks from memory mapped files, compressed archives, network
   523 	pipes, or anything else that has a data read abstraction.
   524 
   525 	There are three built-in data source abstractions:
   526 	    SDL_RWFromFile(), SDL_RWFromFP(), SDL_RWFromMem()
   527 	along with a generic data source allocation function:
   528 	    SDL_AllocRW()
   529 	These data sources can be used like stdio file pointers with the
   530 	following convenience functions:
   531 	    SDL_RWseek(), SDL_RWread(), SDL_RWwrite(), SDL_RWclose()
   532 	These functions are defined in the new header file "SDL_rwops.h"
   533 
   534 	The endian swapping functions have been turned into macros for speed
   535 	and SDL_CalculateEndian() has been removed.  SDL_endian.h now defines
   536 	SDL_BYTEORDER as either SDL_BIG_ENDIAN or SDL_LIL_ENDIAN depending on
   537 	the endianness of the host system.
   538 
   539 	The endian read/write functions now take an SDL_RWops pointer
   540 	instead of a stdio FILE pointer, to support the new data source
   541 	abstraction.
   542 
   543 	The SDL_*LoadWAV() functions have been replaced with a single
   544 	SDL_LoadWAV_RW() function that takes a SDL_RWops pointer as it's
   545 	first parameter, and a flag whether or not to automatically 
   546 	free it as the second parameter.  SDL_LoadWAV() is a macro for
   547 	backward compatibility and convenience:
   548 	    SDL_LoadWAV_RW(SDL_RWFromFile("sample.wav", "rb"), 1, ...);
   549 
   550 	The SDL_*LoadBMP()/SDL_*SaveBMP() functions have each been replaced
   551 	with a single function that takes a SDL_RWops pointer as it's
   552 	first parameter, and a flag whether or not to automatically 
   553 	free it as the second parameter.  SDL_LoadBMP() and SDL_SaveBMP()
   554 	are macros for backward compatibility and convenience:
   555 	    SDL_LoadBMP_RW(SDL_RWFromFile("sample.bmp", "rb"), 1, ...);
   556 	    SDL_SaveBMP_RW(SDL_RWFromFile("sample.bmp", "wb"), 1, ...);
   557 	Note that these functions use SDL_RWseek() extensively, and should
   558 	not be used on pipes or other non-seekable data sources.
   559 
   560 0.9.10:
   561 	The Linux SDL_SysWMInfo and SDL_SysWMMsg structures have been 
   562 	extended to support multiple types of display drivers, as well as
   563         safe access to the X11 display when THREADED_EVENTS is enabled.
   564         The new structures are documented in the SDL_syswm.h header file.
   565 
   566 	Thanks to John Elliott <jce@seasip.demon.co.uk>, the UK keyboard
   567 	should now work properly, as well as the "Windows" keys on US
   568 	keyboards.
   569 
   570 	The Linux CD-ROM code now reads the CD-ROM devices from /etc/fstab
   571 	instead of trying to open each block device on the system.
   572 	The CD must be listed in /etc/fstab as using the iso9660 filesystem.
   573 
   574 	On Linux, if you define THREADED_EVENTS at compile time, a separate
   575 	thread will be spawned to gather X events asynchronously from the
   576 	graphics updates.  This hasn't been extensively tested, but it does
   577 	provide a means of handling keyboard and mouse input in a separate
   578 	thread from the graphics thread.  (This is now enabled by default.)
   579 
   580 	A special access function SDL_PeepEvents() allows you to manipulate
   581 	the event queue in a thread-safe manner, including peeking at events,
   582 	removing events of a specified type, and adding new events of arbitrary
   583 	type to the queue (use the new 'user' member of the SDL_Event type).
   584 
   585 	If you use SDL_PeepEvents() to gather events, then the main graphics
   586 	thread needs to call SDL_PumpEvents() periodically to drive the event
   587 	loop and generate input events.  This is not necessary if SDL has been 
   588 	compiled with THREADED_EVENTS defined, but doesn't hurt.
   589 
   590 	A new function SDL_ThreadID() returns the identifier associated with
   591 	the current thread.
   592 
   593 0.9.9:
   594 	The AUDIO_STEREO format flag has been replaced with a new 'channels'
   595 	member of the SDL_AudioSpec structure.  The channels are 1 for mono
   596 	audio, and 2 for stereo audio.  In the future more channels may be
   597 	supported for 3D surround sound.
   598 
   599 	The SDL_MixAudio() function now takes an additional volume parameter,
   600 	which should be set to SDL_MIX_MAXVOLUME for compatibility with the
   601 	original function.
   602 
   603 	The CD-ROM functions which take a 'cdrom' parameter can now be
   604 	passed NULL, and will act on the last successfully opened CD-ROM.
   605 
   606 0.9.8:
   607 	No changes, bugfixes only.
   608 	
   609 0.9.7:
   610 	No changes, bugfixes only.
   611 	
   612 0.9.6:
   613 	Added a fast rectangle fill function: SDL_FillRect()
   614 
   615 	Addition of a useful function for getting info on the video hardware:
   616 	    const SDL_VideoInfo *SDL_GetVideoInfo(void)
   617         This function replaces SDL_GetDisplayFormat().
   618 
   619 	Initial support for double-buffering:
   620 	  Use the SDL_DOUBLEBUF flag in SDL_SetVideoMode()
   621 	  Update the screen with a new function: SDL_Flip()
   622 
   623 	SDL_AllocSurface() takes two new flags:
   624 	SDL_SRCCOLORKEY means that the surface will be used for colorkey blits
   625 	  and if the hardware supports hardware acceleration of colorkey blits
   626 	  between two surfaces in video memory, to place the surface in video
   627 	  memory if possible, otherwise it will be placed in system memory.
   628 	SDL_SRCALPHA means that the surface will be used for alpha blits and
   629 	  if the hardware supports hardware acceleration of alpha blits between
   630 	  two surfaces in video memory, to place the surface in video memory
   631 	  if possible, otherwise it will be placed in system memory.
   632 	SDL_HWSURFACE now means that the surface will be created with the 
   633 	  same format as the display surface, since having surfaces in video
   634 	  memory is only useful for fast blitting to the screen, and you can't
   635 	  blit surfaces with different surface formats in video memory.
   636 
   637 0.9.5:
   638 	You can now pass a NULL mask to SDL_WM_SetIcon(), and it will assume
   639 	that the icon consists of the entire image.
   640 
   641 	SDL_LowerBlit() is back -- but don't use it on the display surface.
   642 	It is exactly the same as SDL_MiddleBlit(), but doesn't check for
   643 	thread safety.
   644 
   645 	Added SDL_FPLoadBMP(), SDL_FPSaveBMP(), SDL_FPLoadWAV(), which take
   646 	a FILE pointer instead of a file name.
   647 
   648 	Added CD-ROM audio control API:
   649 	    SDL_CDNumDrives()
   650 	    SDL_CDName()
   651 	    SDL_CDOpen()
   652 	    SDL_CDStatus()
   653 	    SDL_CDPlayTracks()
   654 	    SDL_CDPlay()
   655 	    SDL_CDPause()
   656 	    SDL_CDResume()
   657 	    SDL_CDStop()
   658 	    SDL_CDEject()
   659 	    SDL_CDClose()
   660 
   661 0.9.4:
   662 	No changes, bugfixes only.
   663 
   664 0.9.3:
   665 	Mouse motion event now includes relative motion information:
   666 	    Sint16 event->motion.xrel, Sint16 event->motion.yrel
   667 
   668 	X11 keyrepeat handling can be disabled by defining IGNORE_X_KEYREPEAT
   669 	    (Add -DIGNORE_X_KEYREPEAT to CFLAGS line in obj/x11Makefile)
   670 
   671 0.9.2:
   672 	No changes, bugfixes only.
   673 
   674 0.9.1:
   675 	Removed SDL_MapSurface() and SDL_UnmapSurface() -- surfaces are now
   676 	automatically mapped on blit.
   677 
   678 0.8.0:
   679 	SDL stable release