WhatsNew
author Sam Lantinga <slouken@libsdl.org>
Thu, 27 Apr 2006 07:59:16 +0000
changeset 1736 3b2a92126f4d
parent 1545 8d9bb0cf2c2a
child 1737 eacc5bc01d1c
permissions -rw-r--r--
Implemented bug #2, 117:

Date: Mon, 21 Mar 2005 12:06:14 +0100
From: Per Inge Mathisen
Subject: Re: [SDL] Outstanding patches?

The patch adds support for setting SDL_GL_SWAP_CONTROL to Windows and
X11. In Windows you can also query this enum to check that it is
working, or see what the default is - such functionality does not
exist in GLX. For more information on the standards implemented:
http://oss.sgi.com/projects/ogl-sample/registry/SGI/swap_control.txt
http://oss.sgi.com/projects/ogl-sample/registry/EXT/wgl_swap_control.txt
     1 
     2 This is a list of API changes in SDL's version history.
     3 
     4 Version 1.0:
     5 
     6 1.2.10:
     7 	Added SDL_GL_SWAP_CONTROL to wait for vsync in OpenGL applications.
     8 
     9 	Added current_w and current_h to the SDL_VideoInfo structure,
    10 	which is set to the desktop resolution during video intialization,
    11 	and then set to the current resolution when a video mode is set.
    12 
    13 	SDL_SetVideoMode() now accepts 0 for width or height and will use
    14 	the current video mode (or the desktop mode if no mode has been set.)
    15 
    16 	Added SDL_GetKeyRepeat()
    17 
    18 	Added SDL_config.h, with defaults for various build environments.
    19 
    20 1.2.7:
    21 	Added CPU feature detection functions to SDL_cpuinfo.h:
    22 		SDL_HasRDTSC(), SDL_HasMMX(), SDL_Has3DNow(), SDL_HasSSE(),
    23 		SDL_HasAltiVec()
    24 	Added function to create RWops from const memory: SDL_RWFromConstMem()
    25 
    26 1.2.6:
    27 	Added SDL_LoadObject(), SDL_LoadFunction(), and SDL_UnloadObject()
    28 
    29 	Added SDL_GL_MULTISAMPLEBUFFERS and SDL_GL_MULTISAMPLESAMPLES for FSAA
    30 
    31 1.2.5:
    32 	Added SDL_BUTTON_WHEELUP (4) and SDL_BUTTON_WHEELDOWN (5)
    33 
    34 	Added SDL_GL_STEREO for stereoscopic OpenGL contexts
    35 
    36 1.2.0:
    37 	Added SDL_VIDEOEXPOSE event to signal that the screen needs to
    38 	be redrawn.  This is currently only delivered to OpenGL windows
    39 	on X11, though it may be delivered in the future when the video
    40 	memory is lost under DirectX.
    41 
    42 1.1.8:
    43 	You can pass SDL_NOFRAME to SDL_VideoMode() to create a window
    44 	that has no title bar or frame decoration.  Fullscreen video
    45 	modes automatically have this flag set.
    46 
    47 	Added a function to query the clipping rectangle for a surface:
    48 		void SDL_GetClipRect(SDL_Surface *surface, SDL_Rect *rect)
    49 
    50 	Added a function to query the current event filter:
    51 		SDL_EventFilter SDL_GetEventFilter(void)
    52 
    53 	If you pass -1 to SDL_ShowCursor(), it won't change the current
    54 	cursor visibility state, but will still return it.
    55 
    56 	SDL_LockSurface() and SDL_UnlockSurface() are recursive, meaning
    57 	you can nest them as deep as you want, as long as each lock call
    58 	has a matching unlock call.  The surface remains locked until the
    59 	last matching unlock call.
    60 
    61 	Note that you may not blit to or from a locked surface.
    62 
    63 1.1.7:
    64 	The SDL_SetGammaRamp() and SDL_GetGammaRamp() functions now take
    65 	arrays of Uint16 values instead of Uint8 values.  For the most part,
    66 	you can just take your old values and shift them up 8 bits to get
    67 	new correct values for your gamma ramps.
    68 
    69 	You can pass SDL_RLEACCEL in flags passed to SDL_ConvertSurface()
    70         and SDL will try to RLE accelerate colorkey and alpha blits in the
    71 	resulting surface.
    72 
    73 1.1.6:
    74 	Added a function to return the thread ID of a specific thread:
    75 		Uint32 SDL_GetThreadID(SDL_Thread *thread)
    76 	If 'thread' is NULL, this function returns the id for this thread.
    77 
    78 1.1.5:
    79 	The YUV overlay structure has been changed to use an array of
    80 	pitches and pixels representing the planes of a YUV image, to
    81 	better enable hardware acceleration.  The YV12 and IYUV formats
    82 	each have three planes, corresponding to the Y, U, and V portions
    83 	of the image, while packed pixel YUV formats just have one plane.
    84 
    85 	For palettized mode (8bpp), the screen colormap is now split in
    86 	a physical and a logical palette. The physical palette determines
    87 	what colours the screen pixels will get when displayed, and the
    88 	logical palette controls the mapping from blits to/from the screen.
    89 	A new function, SDL_SetPalette() has been added to change
    90 	logical and physical palettes separately. SDL_SetColors() works
    91 	just as before, and is equivalent to calling SDL_SetPalette() with
    92 	a flag argument of (SDL_LOGPAL|SDL_PHYSPAL).
    93 
    94 	SDL_BlitSurface() no longer modifies the source rectangle, only the
    95 	destination rectangle. The width/height members of the destination
    96 	rectangle are ignored, only the position is used.
    97 
    98 	The old source clipping function SDL_SetClipping() has been replaced
    99 	with a more useful function to set the destination clipping rectangle:
   100 		SDL_bool SDL_SetClipRect(SDL_Surface *surface, SDL_Rect *rect)
   101 		
   102 	Added a function to see what subsystems have been initialized:
   103 		Uint32 SDL_WasInit(Uint32 flags)
   104 
   105 	The Big Alpha Flip: SDL now treats alpha as opacity like everybody
   106 	else, and not as transparency:
   107 
   108 	A new cpp symbol: SDL_ALPHA_OPAQUE is defined as 255
   109 	A new cpp symbol: SDL_ALPHA_TRANSPARENT is defined as 0
   110 	Values between 0 and 255 vary from fully transparent to fully opaque.
   111 
   112 	New functions:
   113 	SDL_DisplayFormatAlpha()
   114 	    Returns a surface converted to a format with alpha-channel
   115 	    that can be blit efficiently to the screen. (In other words,
   116 	    like SDL_DisplayFormat() but the resulting surface has
   117 	    an alpha channel.)  This is useful for surfaces with alpha.
   118 	SDL_MapRGBA()
   119 	    Works as SDL_MapRGB() but takes an additional alpha parameter.
   120 	SDL_GetRGBA()
   121 	    Works as SDL_GetRGB() but also returns the alpha value
   122 	    (SDL_ALPHA_OPAQUE for formats without an alpha channel)
   123 
   124 	Both SDL_GetRGB() and SDL_GetRGBA() now always return values in
   125 	the [0..255] interval. Previously, SDL_GetRGB() would return
   126 	(0xf8, 0xfc, 0xf8) for a completely white pixel in RGB565 format.
   127 	(N.B.: This is broken for bit fields < 3 bits.)
   128 
   129 	SDL_MapRGB() returns pixels in which the alpha channel is set opaque.
   130 
   131 	SDL_SetAlpha() can now be used for both setting the per-surface
   132 	alpha, using the new way of thinking of alpha, and also to enable
   133 	and disable per-pixel alpha blending for surfaces with an alpha
   134 	channel:
   135 		To disable alpha blending:
   136 			SDL_SetAlpha(surface, 0, 0);
   137 		To re-enable alpha blending:
   138 			SDL_SetAlpha(surface, SDL_SRCALPHA, 0);
   139 	Surfaces with an alpha channel have blending enabled by default.
   140 
   141 	SDL_SetAlpha() now accepts SDL_RLEACCEL as a flag, which requests
   142 	RLE acceleration of blits, just as like with SDL_SetColorKey().
   143 	This flag can be set for both surfaces with an alpha channel
   144 	and surfaces with an alpha value set by SDL_SetAlpha().
   145 	As always, RLE surfaces must be locked before pixel access is
   146 	allowed, and unlocked before any other SDL operations are done
   147 	on it.
   148 
   149 	The blit semantics for surfaces with and without alpha and colorkey
   150 	have now been defined:
   151 
   152 	RGBA->RGB:
   153 	    SDL_SRCALPHA set:
   154 		alpha-blend (using alpha-channel).
   155 		SDL_SRCCOLORKEY ignored.
   156 	    SDL_SRCALPHA not set:
   157 		copy RGB.
   158 		if SDL_SRCCOLORKEY set, only copy the pixels matching the
   159 		RGB values of the source colour key, ignoring alpha in the
   160 		comparison.
   161 
   162 	RGB->RGBA:
   163 	    SDL_SRCALPHA set:
   164 		alpha-blend (using the source per-surface alpha value);
   165 		set destination alpha to opaque.
   166 	    SDL_SRCALPHA not set:
   167 		copy RGB, set destination alpha to opaque.
   168 	    both:
   169 		if SDL_SRCCOLORKEY set, only copy the pixels matching the
   170 		source colour key.
   171 
   172 	RGBA->RGBA:
   173 	    SDL_SRCALPHA set:
   174 		alpha-blend (using the source alpha channel) the RGB values;
   175 		leave destination alpha untouched. [Note: is this correct?]
   176 		SDL_SRCCOLORKEY ignored.
   177 	    SDL_SRCALPHA not set:
   178 		copy all of RGBA to the destination.
   179 		if SDL_SRCCOLORKEY set, only copy the pixels matching the
   180 		RGB values of the source colour key, ignoring alpha in the
   181 		comparison.
   182 
   183 	RGB->RGB: 
   184 	    SDL_SRCALPHA set:
   185 		alpha-blend (using the source per-surface alpha value).
   186 	    SDL_SRCALPHA not set:
   187 		copy RGB.
   188 	    both:
   189 		if SDL_SRCCOLORKEY set, only copy the pixels matching the
   190 		source colour key.
   191 
   192 	As a special case, blits from surfaces with per-surface alpha
   193 	value of 128 (50% transparency) are optimised and much faster
   194 	than other alpha values. This does not apply to surfaces with
   195 	alpha channels (per-pixel alpha).
   196 
   197 	New functions for manipulating the gamma of the display have
   198 	been added:
   199 		int SDL_SetGamma(float red, float green, float blue);
   200 		int SDL_SetGammaRamp(Uint8 *red, Uint8 *green, Uint8 *blue);
   201 		int SDL_GetGammaRamp(Uint8 *red, Uint8 *green, Uint8 *blue);
   202 	Gamma ramps are tables with 256 entries which map the screen color
   203 	components into actually displayed colors.  For an example of
   204 	implementing gamma correction and gamma fades, see test/testgamma.c
   205 	Gamma control is not supported on all hardware.
   206 
   207 1.1.4:
   208 	The size of the SDL_CDtrack structure changed from 8 to 12 bytes
   209 	as the size of the length member was extended to 32 bits.
   210 
   211         You can now use SDL for 2D blitting with a GL mode by passing the
   212 	SDL_OPENGLBLIT flag to SDL_SetVideoMode().  You can specify 16 or
   213 	32 bpp, and the data in the framebuffer is put into the GL scene
   214 	when you call SDL_UpdateRects(), and the scene will be visible
   215 	when you call SDL_GL_SwapBuffers().
   216 
   217 	Run the "testgl" test program with the -logo command line option
   218 	to see an example of this blending of 2D and 3D in SDL.
   219 
   220 1.1.3:
   221 	Added SDL_FreeRW() to the API, to complement SDL_AllocRW()
   222 
   223 	Added resizable window support - just add SDL_RESIZABLE to the
   224 	SDL_SetVideoMode() flags, and then wait for SDL_VIDEORESIZE events.
   225 	See SDL_events.h for details on the new SDL_ResizeEvent structure.
   226 
   227 	Added condition variable support, based on mutexes and semaphores.
   228 		SDL_CreateCond()
   229 		SDL_DestroyCond()
   230 		SDL_CondSignal()
   231 		SDL_CondBroadcast()
   232 		SDL_CondWait()
   233 		SDL_CondTimedWait()
   234 	The new function prototypes are in SDL_mutex.h
   235 
   236 	Added counting semaphore support, based on the mutex primitive.
   237 		SDL_CreateSemaphore()
   238 		SDL_DestroySemaphore()
   239 		SDL_SemWait()
   240 		SDL_SemTryWait()
   241 		SDL_SemWaitTimeout()
   242 		SDL_SemPost()
   243 		SDL_SemValue()
   244 	The new function prototypes are in SDL_mutex.h
   245 
   246 	Added support for asynchronous blitting.  To take advantage of this,
   247 	you must set the SDL_ASYNCBLIT flag when setting the video mode and
   248 	creating surfaces that you want accelerated in this way.  You must
   249 	lock surfaces that have this flag set, and the lock will block until
   250 	any queued blits have completed.
   251 
   252 	Added YUV video overlay support.
   253 	The supported YUV formats are: YV12, IYUV, YUY2, UYVY, and YVYU.
   254 	This function creates an overlay surface:
   255 		SDL_CreateYUVOverlay()
   256 	You must lock and unlock the overlay to get access to the data:
   257 		SDL_LockYUVOverlay() SDL_UnlockYUVOverlay()
   258 	You can then display the overlay:
   259 		SDL_DisplayYUVOverlay()
   260 	You must free the overlay when you are done using it:
   261 		SDL_FreeYUVOverlay()
   262 	See SDL_video.h for the full function prototypes.
   263 
   264 	The joystick hat position constants have been changed:
   265 	Old constant            New constant
   266 	------------            ------------
   267 	     0                  SDL_HAT_CENTERED
   268 	     1                  SDL_HAT_UP
   269 	     2                  SDL_HAT_RIGHTUP
   270 	     3                  SDL_HAT_RIGHT
   271 	     4                  SDL_HAT_RIGHTDOWN
   272 	     5                  SDL_HAT_DOWN
   273 	     6                  SDL_HAT_LEFTDOWN
   274 	     7                  SDL_HAT_LEFT
   275 	     8                  SDL_HAT_LEFTUP
   276 	The new constants are bitmasks, so you can check for the
   277 	individual axes like this:
   278 		if ( hat_position & SDL_HAT_UP ) {
   279 		}
   280 	and you'll catch left-up, up, and right-up.
   281 
   282 1.1.2:
   283 	Added multiple timer support:
   284 		SDL_AddTimer() and SDL_RemoveTimer()
   285 
   286 	SDL_WM_SetIcon() now respects the icon colorkey if mask is NULL.
   287 
   288 1.1.0:
   289 	Added initial OpenGL support.
   290 	First set GL attributes (such as RGB depth, alpha depth, etc.)
   291 		SDL_GL_SetAttribute()
   292 	Then call SDL_SetVideoMode() with the SDL_OPENGL flag.
   293 	Perform all of your normal GL drawing.
   294 	Finally swap the buffers with the new SDL function:
   295 		SDL_GL_SwapBuffers()
   296 	See the new 'testgl' test program for an example of using GL with SDL.
   297 
   298 	You can load GL extension functions by using the function:
   299 		SDL_GL_LoadProcAddress()
   300 
   301 	Added functions to initialize and cleanup specific SDL subsystems:
   302 		SDL_InitSubSystem() and SDL_QuitSubSystem()
   303 
   304 	Added user-defined event type:
   305 		typedef struct {
   306         		Uint8 type;
   307         		int code;
   308         		void *data1;
   309         		void *data2;
   310 		} SDL_UserEvent;
   311 	This structure is in the "user" member of an SDL_Event.
   312 
   313 	Added a function to push events into the event queue:
   314 		SDL_PushEvent()
   315 
   316 	Example of using the new SDL user-defined events:
   317 	{
   318 		SDL_Event event;
   319 
   320 		event.type = SDL_USEREVENT;
   321 		event.user.code = my_event_code;
   322 		event.user.data1 = significant_data;
   323 		event.user.data2 = 0;
   324 		SDL_PushEvent(&event);
   325 	}
   326 
   327 	Added a function to get mouse deltas since last query:
   328 		SDL_GetRelativeMouseState()
   329 
   330 	Added a boolean datatype to SDL_types.h:
   331 		SDL_bool = { SDL_TRUE, SDL_FALSE }
   332 
   333 	Added a function to get the current audio status:
   334 		SDL_GetAudioState();
   335 	It returns one of:
   336 		SDL_AUDIO_STOPPED,
   337 		SDL_AUDIO_PLAYING,
   338 		SDL_AUDIO_PAUSED
   339 
   340 	Added an AAlib driver (ASCII Art) - by Stephane Peter.
   341 
   342 1.0.6:
   343 	The input grab state is reset after each call to SDL_SetVideoMode().
   344 	The input is grabbed by default in fullscreen mode, and ungrabbed in
   345 	windowed mode.  If you want to set input grab to a particular value,
   346 	you should set it after each call to SDL_SetVideoMode().
   347 
   348 1.0.5:
   349 	Exposed SDL_AudioInit(), SDL_VideoInit()
   350 	Added SDL_AudioDriverName() and SDL_VideoDriverName()
   351 
   352 	Added new window manager function:
   353 		SDL_WM_ToggleFullScreen()
   354 	This is currently implemented only on Linux
   355 
   356 	The ALT-ENTER code has been removed - it's not appropriate for a
   357 	lib to bind keys when they aren't even emergency escape sequences.
   358 
   359 	ALT-ENTER functionality can be implemented with the following code:
   360 
   361 	int Handle_AltEnter(const SDL_Event *event)
   362 	{
   363 	    if ( event->type == SDL_KEYDOWN ) {
   364 	        if ( (event->key.keysym.sym == SDLK_RETURN) &&
   365 	             (event->key.keysym.mod & KMOD_ALT) ) {   
   366 	                SDL_WM_ToggleFullScreen(SDL_GetVideoSurface());
   367 	                return(0);
   368 	        }
   369 	    }
   370 	    return(1);
   371 	}
   372 	SDL_SetEventFilter(Handle_AltEnter);
   373 
   374 1.0.3:
   375 	Under X11, if you grab the input and hide the mouse cursor,
   376 	the mouse will go into a "relative motion" mode where you
   377 	will always get relative motion events no matter how far in
   378 	each direction you move the mouse - relative motion is not
   379 	bounded by the edges of the window (though the absolute values
   380 	of the mouse positions are clamped by the size of the window).
   381 	The SVGAlib, framebuffer console, and DirectInput drivers all
   382 	have this behavior naturally, and the GDI and BWindow drivers
   383 	never go into "relative motion" mode.
   384 
   385 1.0.2:
   386 	Added a function to enable keyboard repeat:
   387 		SDL_EnableKeyRepeat()
   388 
   389 	Added a function to grab the mouse and keyboard input
   390 		SDL_WM_GrabInput()
   391 
   392 	Added a function to iconify the window.
   393 		SDL_WM_IconifyWindow()
   394 	If this function succeeds, the application will receive an event
   395 	signaling SDL_APPACTIVE event 
   396 
   397 1.0.1:
   398 	Added constants to SDL_audio.h for 16-bit native byte ordering:
   399 		AUDIO_U16SYS, AUDIO_S16SYS
   400 
   401 1.0.0:
   402 	New public release
   403 
   404 Version 0.11:
   405 
   406 0.11.5:
   407 	A new function SDL_GetVideoSurface() has been added, and returns
   408 	a pointer to the current display surface.
   409 
   410 	SDL_AllocSurface() has been renamed SDL_CreateRGBSurface(), and
   411 	a new function SDL_CreateRGBSurfaceFrom() has been added to allow
   412 	creating an SDL surface from an existing pixel data buffer.
   413 
   414 	Added SDL_GetRGB() to the headers and documentation.
   415 
   416 0.11.4:
   417 	SDL_SetLibraryPath() is no longer meaningful, and has been removed.
   418 
   419 0.11.3:
   420 	A new flag for SDL_Init(), SDL_INIT_NOPARACHUTE, prevents SDL from
   421 	installing fatal signal handlers on operating systems that support
   422 	them.
   423 
   424 Version 0.9:
   425 
   426 0.9.15:
   427 	SDL_CreateColorCursor() has been removed.  Color cursors should
   428 	be implemented as sprites, blitted by the application when the
   429 	cursor moves.  To get smooth color cursor updates when the app
   430 	is busy, pass the SDL_INIT_EVENTTHREAD flag to SDL_Init().  This
   431 	allows you to handle the mouse motion in another thread from an
   432 	event filter function, but is currently only supported by Linux
   433 	and BeOS.  Note that you'll have to protect the display surface
   434 	from multi-threaded access by using mutexes if you do this.
   435 
   436 	Thread-safe surface support has been removed from SDL.
   437 	This makes blitting somewhat faster, by removing SDL_MiddleBlit().
   438 	Code that used SDL_MiddleBlit() should use SDL_LowerBlit() instead.
   439 	You can make your surfaces thread-safe by allocating your own
   440 	mutex and making lock/unlock calls around accesses to your surface.
   441 
   442 0.9.14:
   443 	SDL_GetMouseState() now takes pointers to int rather than Uint16.
   444 
   445 	If you set the SDL_WINDOWID environment variable under UNIX X11,
   446 	SDL will use that as the main window instead of creating it's own.
   447 	This is an unsupported extension to SDL, and not portable at all.
   448 
   449 0.9.13:
   450 	Added a function SDL_SetLibraryPath() which can be used to specify
   451 	the directory containing the SDL dynamic libraries.  This is useful
   452 	for commercial applications which ship with particular versions
   453 	of the libraries, and for security on multi-user systems.
   454 	If this function is not used, the default system directories are 
   455 	searched using the native dynamic object loading mechanism.
   456 
   457 	In order to support C linkage under Visual C++, you must declare
   458 	main() without any return type:
   459 		main(int argc, char *argv[]) {
   460 			/* Do the program... */
   461 			return(0);
   462 		}
   463 	C++ programs should also return a value if compiled under VC++.
   464 
   465 	The blit_endian member of the SDL_VideoInfo struct has been removed.
   466 
   467 	SDL_SymToASCII() has been replaced with SDL_GetKeyName(), so there
   468 	is now no longer any function to translate a keysym to a character.
   469 
   470 	The SDL_keysym structure has been extended with a 'scancode' and
   471 	'unicode' member.  The 'scancode' is a hardware specific scancode
   472 	for the key that was pressed, and may be 0.  The 'unicode' member
   473 	is a 16-bit UNICODE translation of the key that was pressed along
   474 	with any modifiers or compose keys that have been pressed.
   475 	If no UNICODE translation exists for the key, 'unicode' will be 0.
   476 
   477 	Added a function SDL_EnableUNICODE() to enable/disable UNICODE
   478 	translation of character keypresses.  Translation defaults off.
   479 
   480 	To convert existing code to use the new API, change code which
   481 	uses SDL_SymToASCII() to get the keyname to use SDL_GetKeyName(),
   482 	and change code which uses it to get the ASCII value of a sym to
   483 	use the 'unicode' member of the event keysym.
   484 
   485 0.9.12:
   486 	There is partial support for 64-bit datatypes.  I don't recommend 
   487 	you use this if you have a choice, because 64-bit datatypes are not
   488 	supported on many platforms.  On platforms for which it is supported,
   489 	the SDL_HAS_64BIT_TYPE C preprocessor define will be enabled, and
   490 	you can use the Uint64 and Sint64 datatypes.
   491 
   492 	Added functions to SDL_endian.h to support 64-bit datatypes:
   493 	    SDL_SwapLE64(), SDL_SwapBE64(),
   494 	    SDL_ReadLE64(), SDL_ReadBE64(), SDL_WriteLE64(), SDL_WriteBE64()
   495 
   496 	A new member "len_ratio" has been added to the SDL_AudioCVT structure,
   497 	and allows you to determine either the original buffer length or the
   498 	converted buffer length, given the other.
   499 
   500 	A new function SDL_FreeWAV() has been added to the API to free data
   501 	allocated by SDL_LoadWAV_RW().  This is necessary under Win32 since
   502 	the gcc compiled DLL uses a different heap than VC++ compiled apps.
   503 
   504 	SDL now has initial support for international keyboards using the
   505 	Latin character set.
   506 	If a particular mapping is desired, you can set the DEFAULT_KEYBOARD
   507 	compile-time variable, or you can set the environment variable 
   508 	"SDL_KEYBOARD" to a string identifying the keyboard mapping you desire.
   509 	The valid values for these variables can be found in SDL_keyboard.c
   510 
   511 	Full support for German and French keyboards under X11 is implemented.
   512 
   513 0.9.11:
   514 	The THREADED_EVENTS compile-time define has been replaced with the
   515 	SDL_INIT_EVENTTHREAD flag.  If this flag is passed to SDL_Init(),
   516 	SDL will create a separate thread to perform input event handling.
   517 	If this flag is passed to SDL_Init(), and the OS doesn't support 
   518 	event handling in a separate thread, SDL_Init() will fail.
   519 	Be sure to add calls to SDL_Delay() in your main thread to allow
   520 	the OS to schedule your event thread, or it may starve, leading
   521 	to slow event delivery and/or dropped events.
   522 	Currently MacOS and Win32 do not support this flag, while BeOS 
   523 	and Linux do support it.  I recommend that your application only
   524 	use this flag if absolutely necessary.
   525 
   526 	The SDL thread function passed to SDL_CreateThread() now returns a
   527 	status.  This status can be retrieved by passing a non-NULL pointer
   528 	as the 'status' argument to SDL_WaitThread().
   529 
   530 	The volume parameter to SDL_MixAudio() has been increased in range
   531 	from (0-8) to (0-128)
   532 
   533 	SDL now has a data source abstraction which can encompass a file,
   534 	an area of memory, or any custom object you can envision.  It uses
   535 	these abstractions, SDL_RWops, in the endian read/write functions,
   536 	and the built-in WAV and BMP file loaders.  This means you can load
   537 	WAV chunks from memory mapped files, compressed archives, network
   538 	pipes, or anything else that has a data read abstraction.
   539 
   540 	There are three built-in data source abstractions:
   541 	    SDL_RWFromFile(), SDL_RWFromFP(), SDL_RWFromMem()
   542 	along with a generic data source allocation function:
   543 	    SDL_AllocRW()
   544 	These data sources can be used like stdio file pointers with the
   545 	following convenience functions:
   546 	    SDL_RWseek(), SDL_RWread(), SDL_RWwrite(), SDL_RWclose()
   547 	These functions are defined in the new header file "SDL_rwops.h"
   548 
   549 	The endian swapping functions have been turned into macros for speed
   550 	and SDL_CalculateEndian() has been removed.  SDL_endian.h now defines
   551 	SDL_BYTEORDER as either SDL_BIG_ENDIAN or SDL_LIL_ENDIAN depending on
   552 	the endianness of the host system.
   553 
   554 	The endian read/write functions now take an SDL_RWops pointer
   555 	instead of a stdio FILE pointer, to support the new data source
   556 	abstraction.
   557 
   558 	The SDL_*LoadWAV() functions have been replaced with a single
   559 	SDL_LoadWAV_RW() function that takes a SDL_RWops pointer as it's
   560 	first parameter, and a flag whether or not to automatically 
   561 	free it as the second parameter.  SDL_LoadWAV() is a macro for
   562 	backward compatibility and convenience:
   563 	    SDL_LoadWAV_RW(SDL_RWFromFile("sample.wav", "rb"), 1, ...);
   564 
   565 	The SDL_*LoadBMP()/SDL_*SaveBMP() functions have each been replaced
   566 	with a single function that takes a SDL_RWops pointer as it's
   567 	first parameter, and a flag whether or not to automatically 
   568 	free it as the second parameter.  SDL_LoadBMP() and SDL_SaveBMP()
   569 	are macros for backward compatibility and convenience:
   570 	    SDL_LoadBMP_RW(SDL_RWFromFile("sample.bmp", "rb"), 1, ...);
   571 	    SDL_SaveBMP_RW(SDL_RWFromFile("sample.bmp", "wb"), 1, ...);
   572 	Note that these functions use SDL_RWseek() extensively, and should
   573 	not be used on pipes or other non-seekable data sources.
   574 
   575 0.9.10:
   576 	The Linux SDL_SysWMInfo and SDL_SysWMMsg structures have been 
   577 	extended to support multiple types of display drivers, as well as
   578         safe access to the X11 display when THREADED_EVENTS is enabled.
   579         The new structures are documented in the SDL_syswm.h header file.
   580 
   581 	Thanks to John Elliott <jce@seasip.demon.co.uk>, the UK keyboard
   582 	should now work properly, as well as the "Windows" keys on US
   583 	keyboards.
   584 
   585 	The Linux CD-ROM code now reads the CD-ROM devices from /etc/fstab
   586 	instead of trying to open each block device on the system.
   587 	The CD must be listed in /etc/fstab as using the iso9660 filesystem.
   588 
   589 	On Linux, if you define THREADED_EVENTS at compile time, a separate
   590 	thread will be spawned to gather X events asynchronously from the
   591 	graphics updates.  This hasn't been extensively tested, but it does
   592 	provide a means of handling keyboard and mouse input in a separate
   593 	thread from the graphics thread.  (This is now enabled by default.)
   594 
   595 	A special access function SDL_PeepEvents() allows you to manipulate
   596 	the event queue in a thread-safe manner, including peeking at events,
   597 	removing events of a specified type, and adding new events of arbitrary
   598 	type to the queue (use the new 'user' member of the SDL_Event type).
   599 
   600 	If you use SDL_PeepEvents() to gather events, then the main graphics
   601 	thread needs to call SDL_PumpEvents() periodically to drive the event
   602 	loop and generate input events.  This is not necessary if SDL has been 
   603 	compiled with THREADED_EVENTS defined, but doesn't hurt.
   604 
   605 	A new function SDL_ThreadID() returns the identifier associated with
   606 	the current thread.
   607 
   608 0.9.9:
   609 	The AUDIO_STEREO format flag has been replaced with a new 'channels'
   610 	member of the SDL_AudioSpec structure.  The channels are 1 for mono
   611 	audio, and 2 for stereo audio.  In the future more channels may be
   612 	supported for 3D surround sound.
   613 
   614 	The SDL_MixAudio() function now takes an additional volume parameter,
   615 	which should be set to SDL_MIX_MAXVOLUME for compatibility with the
   616 	original function.
   617 
   618 	The CD-ROM functions which take a 'cdrom' parameter can now be
   619 	passed NULL, and will act on the last successfully opened CD-ROM.
   620 
   621 0.9.8:
   622 	No changes, bugfixes only.
   623 	
   624 0.9.7:
   625 	No changes, bugfixes only.
   626 	
   627 0.9.6:
   628 	Added a fast rectangle fill function: SDL_FillRect()
   629 
   630 	Addition of a useful function for getting info on the video hardware:
   631 	    const SDL_VideoInfo *SDL_GetVideoInfo(void)
   632         This function replaces SDL_GetDisplayFormat().
   633 
   634 	Initial support for double-buffering:
   635 	  Use the SDL_DOUBLEBUF flag in SDL_SetVideoMode()
   636 	  Update the screen with a new function: SDL_Flip()
   637 
   638 	SDL_AllocSurface() takes two new flags:
   639 	SDL_SRCCOLORKEY means that the surface will be used for colorkey blits
   640 	  and if the hardware supports hardware acceleration of colorkey blits
   641 	  between two surfaces in video memory, to place the surface in video
   642 	  memory if possible, otherwise it will be placed in system memory.
   643 	SDL_SRCALPHA means that the surface will be used for alpha blits and
   644 	  if the hardware supports hardware acceleration of alpha blits between
   645 	  two surfaces in video memory, to place the surface in video memory
   646 	  if possible, otherwise it will be placed in system memory.
   647 	SDL_HWSURFACE now means that the surface will be created with the 
   648 	  same format as the display surface, since having surfaces in video
   649 	  memory is only useful for fast blitting to the screen, and you can't
   650 	  blit surfaces with different surface formats in video memory.
   651 
   652 0.9.5:
   653 	You can now pass a NULL mask to SDL_WM_SetIcon(), and it will assume
   654 	that the icon consists of the entire image.
   655 
   656 	SDL_LowerBlit() is back -- but don't use it on the display surface.
   657 	It is exactly the same as SDL_MiddleBlit(), but doesn't check for
   658 	thread safety.
   659 
   660 	Added SDL_FPLoadBMP(), SDL_FPSaveBMP(), SDL_FPLoadWAV(), which take
   661 	a FILE pointer instead of a file name.
   662 
   663 	Added CD-ROM audio control API:
   664 	    SDL_CDNumDrives()
   665 	    SDL_CDName()
   666 	    SDL_CDOpen()
   667 	    SDL_CDStatus()
   668 	    SDL_CDPlayTracks()
   669 	    SDL_CDPlay()
   670 	    SDL_CDPause()
   671 	    SDL_CDResume()
   672 	    SDL_CDStop()
   673 	    SDL_CDEject()
   674 	    SDL_CDClose()
   675 
   676 0.9.4:
   677 	No changes, bugfixes only.
   678 
   679 0.9.3:
   680 	Mouse motion event now includes relative motion information:
   681 	    Sint16 event->motion.xrel, Sint16 event->motion.yrel
   682 
   683 	X11 keyrepeat handling can be disabled by defining IGNORE_X_KEYREPEAT
   684 	    (Add -DIGNORE_X_KEYREPEAT to CFLAGS line in obj/x11Makefile)
   685 
   686 0.9.2:
   687 	No changes, bugfixes only.
   688 
   689 0.9.1:
   690 	Removed SDL_MapSurface() and SDL_UnmapSurface() -- surfaces are now
   691 	automatically mapped on blit.
   692 
   693 0.8.0:
   694 	SDL stable release