Mercurial > sdl-ios-xcode
view src/SDL.c @ 4139:568c9b3c0167 SDL-1.2
* Added configure option --enable-screensaver, to allow enabling the screensaver by default.
* Use XResetScreenSaver() instead of disabling screensaver entirely.
Full discussion summary from Erik on the SDL mailing list:
Current behaviour
=================
SDL changes the user's display power management settings without
permission from the user and without telling the user.
The interface that it uses to do so is DPMSDisable/DPMSEnable, which
should only ever be used by configuration utilities like KControl, never
by normal application programs, let alone by the libraries that they
use. Using an interface that is not at all intended for what SDL tries
to achieve means that it will not work as it should. Firstly, the power
management is completely disabled during the whole lifetime of the SDL
program, not only when it should be. Secondly, it makes SDL
non-reentrant, meaning that things will break when multiple SDL programs
are clients of the same X server simultaneously. Thirdly, no cleanup
mechanism ensures that the setting is restored if the client does not do
that (for example if it crashes).
In addition to that, this interface is broken on xorg,
[http://bugs.freedesktop.org/show_bug.cgi?id=13962], so what SDL tries
to do does not work at all on that implementation of the X Window
System. (The reason that the DPMSEnable works in KControl is that it
calls DPMSSetTimeout immediately after,
[http://websvn.kde.org/tags/KDE/3.5.9/kdebase/kcontrol/energy/energy.cpp?annotate=774532#l343]).
The problems that the current behaviour causes
==============================================
1. Information leak. When the user is away, someone might see what the
user has on the display when the user counts on the screensaver
preventing this. This does not even require physical access to the
workstation, it is enough to see it from a distance.
2. Draining battery. An SDL program that runs on a laptop will quickly
drain the battery while the user is away. The system will soon shut down
and require recharging before being usable again, while it should in
fact have consumed very little energy if the user's settings would have
been obeyed.
3. Wasting energy. Even if battery issues are not considered, energy as
such is wasted.
4. Display wear. The display may be worn out.
The problems that the current behaviour tries to solve
======================================================
1. Preventing screensaver while playing movies.
Many SDL applications are media players. They have reasons to prevent
screensavers from being activated while a movie is being played. When a
user clicks on the play button it can be interpreted as saying "play
this movie, but do not turn off the display while playing it, because I
will watch it even though I do not interact with the system".
2. Preventing screensaver when some input bypasses X.
Sometimes SDL uses input from another source than the X server, so
that the X server is bypassed. This obviously breaks the screensaver
handling. SDL tries to work around that.
3. Preventing screensaver when all input bypasses X.
There is something called Direct Graphics Access mode, where a
program takes control of both the display and the input devices from the
X server. This obviously means that the X server can not handle the
screensaver alone, since screensaver handling depends on input handling.
SDL does not do what it should to help the X server to handle the
screensaver. Nor does SDL take care of screeensaver handling itself. SDL
simply disables the screensaver completely.
How the problems should be solved
=================================
The correct way for an application program to prevent the screensaver
under X is to call XResetScreenSaver. This was recently discovered and
implemented by the mplayer developers,
[http://svn.mplayerhq.hu/mplayer?view=rev&revision=25637]. SDL needs to
wrap this in an API call (SDL_ResetScreenSaver) and implement it for the
other video targets (if they do not have a corresponding call, SDL
should do what it takes on that particular target, for example sending
fake key events).
1. When a movie is played, the player should reset the screensaver when
the animation is advanced to a new frame. The same applies to anything
similar, like slideshows.
2. When the X server is handling input, it must handle all input
(keyboards, mice, gamepads, ...). This is necessary, not only to be able
to handle the screensaver, but also so that it can send the events to
the correct (the currently active) client. If there is an input device
that the X server can not handle for some reason (such as lack of Plug
and Play capability), the program that handles the device as a
workaround must simulate what would happen if the X server would have
handled the device, by calling XResetScreenSaver when input is received
from the device.
3. When the X server is not handling the input, it depends on the
program that does to call XResetScreenSaver whenever an input event
occurs. Alternatively the program must handle the screensaver countdown
internally and call XActivateScreenSaver.
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Fri, 29 Feb 2008 13:55:44 +0000 |
parents | 8582c6a5ca16 |
children | a1b03ba2fcd0 |
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/* SDL - Simple DirectMedia Layer Copyright (C) 1997-2006 Sam Lantinga This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA Sam Lantinga slouken@libsdl.org */ #include "SDL_config.h" /* Initialization code for SDL */ #include "SDL.h" #include "SDL_fatal.h" #if !SDL_VIDEO_DISABLED #include "video/SDL_leaks.h" #endif #if SDL_THREAD_PTH #include <pth.h> #endif /* Initialization/Cleanup routines */ #if !SDL_JOYSTICK_DISABLED extern int SDL_JoystickInit(void); extern void SDL_JoystickQuit(void); #endif #if !SDL_CDROM_DISABLED extern int SDL_CDROMInit(void); extern void SDL_CDROMQuit(void); #endif #if !SDL_TIMERS_DISABLED extern void SDL_StartTicks(void); extern int SDL_TimerInit(void); extern void SDL_TimerQuit(void); #endif /* The current SDL version */ static SDL_version version = { SDL_MAJOR_VERSION, SDL_MINOR_VERSION, SDL_PATCHLEVEL }; /* The initialized subsystems */ static Uint32 SDL_initialized = 0; #if !SDL_TIMERS_DISABLED static Uint32 ticks_started = 0; #endif #ifdef CHECK_LEAKS int surfaces_allocated = 0; #endif int SDL_InitSubSystem(Uint32 flags) { #if !SDL_VIDEO_DISABLED /* Initialize the video/event subsystem */ if ( (flags & SDL_INIT_VIDEO) && !(SDL_initialized & SDL_INIT_VIDEO) ) { if ( SDL_VideoInit(SDL_getenv("SDL_VIDEODRIVER"), (flags&SDL_INIT_EVENTTHREAD)) < 0 ) { return(-1); } SDL_initialized |= SDL_INIT_VIDEO; } #else if ( flags & SDL_INIT_VIDEO ) { SDL_SetError("SDL not built with video support"); return(-1); } #endif #if !SDL_AUDIO_DISABLED /* Initialize the audio subsystem */ if ( (flags & SDL_INIT_AUDIO) && !(SDL_initialized & SDL_INIT_AUDIO) ) { if ( SDL_AudioInit(SDL_getenv("SDL_AUDIODRIVER")) < 0 ) { return(-1); } SDL_initialized |= SDL_INIT_AUDIO; } #else if ( flags & SDL_INIT_AUDIO ) { SDL_SetError("SDL not built with audio support"); return(-1); } #endif #if !SDL_TIMERS_DISABLED /* Initialize the timer subsystem */ if ( ! ticks_started ) { SDL_StartTicks(); ticks_started = 1; } if ( (flags & SDL_INIT_TIMER) && !(SDL_initialized & SDL_INIT_TIMER) ) { if ( SDL_TimerInit() < 0 ) { return(-1); } SDL_initialized |= SDL_INIT_TIMER; } #else if ( flags & SDL_INIT_TIMER ) { SDL_SetError("SDL not built with timer support"); return(-1); } #endif #if !SDL_JOYSTICK_DISABLED /* Initialize the joystick subsystem */ if ( (flags & SDL_INIT_JOYSTICK) && !(SDL_initialized & SDL_INIT_JOYSTICK) ) { if ( SDL_JoystickInit() < 0 ) { return(-1); } SDL_initialized |= SDL_INIT_JOYSTICK; } #else if ( flags & SDL_INIT_JOYSTICK ) { SDL_SetError("SDL not built with joystick support"); return(-1); } #endif #if !SDL_CDROM_DISABLED /* Initialize the CD-ROM subsystem */ if ( (flags & SDL_INIT_CDROM) && !(SDL_initialized & SDL_INIT_CDROM) ) { if ( SDL_CDROMInit() < 0 ) { return(-1); } SDL_initialized |= SDL_INIT_CDROM; } #else if ( flags & SDL_INIT_CDROM ) { SDL_SetError("SDL not built with cdrom support"); return(-1); } #endif return(0); } int SDL_Init(Uint32 flags) { #if !SDL_THREADS_DISABLED && SDL_THREAD_PTH if (!pth_init()) { return -1; } #endif /* Clear the error message */ SDL_ClearError(); /* Initialize the desired subsystems */ if ( SDL_InitSubSystem(flags) < 0 ) { return(-1); } /* Everything is initialized */ if ( !(flags & SDL_INIT_NOPARACHUTE) ) { SDL_InstallParachute(); } return(0); } void SDL_QuitSubSystem(Uint32 flags) { /* Shut down requested initialized subsystems */ #if !SDL_CDROM_DISABLED if ( (flags & SDL_initialized & SDL_INIT_CDROM) ) { SDL_CDROMQuit(); SDL_initialized &= ~SDL_INIT_CDROM; } #endif #if !SDL_JOYSTICK_DISABLED if ( (flags & SDL_initialized & SDL_INIT_JOYSTICK) ) { SDL_JoystickQuit(); SDL_initialized &= ~SDL_INIT_JOYSTICK; } #endif #if !SDL_TIMERS_DISABLED if ( (flags & SDL_initialized & SDL_INIT_TIMER) ) { SDL_TimerQuit(); SDL_initialized &= ~SDL_INIT_TIMER; } #endif #if !SDL_AUDIO_DISABLED if ( (flags & SDL_initialized & SDL_INIT_AUDIO) ) { SDL_AudioQuit(); SDL_initialized &= ~SDL_INIT_AUDIO; } #endif #if !SDL_VIDEO_DISABLED if ( (flags & SDL_initialized & SDL_INIT_VIDEO) ) { SDL_VideoQuit(); SDL_initialized &= ~SDL_INIT_VIDEO; } #endif } Uint32 SDL_WasInit(Uint32 flags) { if ( ! flags ) { flags = SDL_INIT_EVERYTHING; } return (SDL_initialized&flags); } void SDL_Quit(void) { /* Quit all subsystems */ #ifdef DEBUG_BUILD printf("[SDL_Quit] : Enter! Calling QuitSubSystem()\n"); fflush(stdout); #endif SDL_QuitSubSystem(SDL_INIT_EVERYTHING); #ifdef CHECK_LEAKS #ifdef DEBUG_BUILD printf("[SDL_Quit] : CHECK_LEAKS\n"); fflush(stdout); #endif /* Print the number of surfaces not freed */ if ( surfaces_allocated != 0 ) { fprintf(stderr, "SDL Warning: %d SDL surfaces extant\n", surfaces_allocated); } #endif #ifdef DEBUG_BUILD printf("[SDL_Quit] : SDL_UninstallParachute()\n"); fflush(stdout); #endif /* Uninstall any parachute signal handlers */ SDL_UninstallParachute(); #if !SDL_THREADS_DISABLED && SDL_THREAD_PTH pth_kill(); #endif #ifdef DEBUG_BUILD printf("[SDL_Quit] : Returning!\n"); fflush(stdout); #endif } /* Return the library version number */ const SDL_version * SDL_Linked_Version(void) { return(&version); } #if defined(__OS2__) /* Building for OS/2 */ #ifdef __WATCOMC__ #define INCL_DOSERRORS #define INCL_DOSEXCEPTIONS #include <os2.h> /* Exception handler to prevent the Audio thread hanging, making a zombie process! */ ULONG _System SDL_Main_ExceptionHandler(PEXCEPTIONREPORTRECORD pERepRec, PEXCEPTIONREGISTRATIONRECORD pERegRec, PCONTEXTRECORD pCtxRec, PVOID p) { if (pERepRec->fHandlerFlags & EH_EXIT_UNWIND) return XCPT_CONTINUE_SEARCH; if (pERepRec->fHandlerFlags & EH_UNWINDING) return XCPT_CONTINUE_SEARCH; if (pERepRec->fHandlerFlags & EH_NESTED_CALL) return XCPT_CONTINUE_SEARCH; /* Do cleanup at every fatal exception! */ if (((pERepRec->ExceptionNum & XCPT_SEVERITY_CODE) == XCPT_FATAL_EXCEPTION) && (pERepRec->ExceptionNum != XCPT_BREAKPOINT) && (pERepRec->ExceptionNum != XCPT_SINGLE_STEP) ) { if (SDL_initialized & SDL_INIT_AUDIO) { /* This removes the zombie audio thread in case of emergency. */ #ifdef DEBUG_BUILD printf("[SDL_Main_ExceptionHandler] : Calling SDL_CloseAudio()!\n"); #endif SDL_CloseAudio(); } } return (XCPT_CONTINUE_SEARCH); } EXCEPTIONREGISTRATIONRECORD SDL_Main_xcpthand = {0, SDL_Main_ExceptionHandler}; /* The main DLL entry for DLL Initialization and Uninitialization: */ unsigned _System LibMain(unsigned hmod, unsigned termination) { if (termination) { #ifdef DEBUG_BUILD /* printf("[SDL DLL Unintialization] : Removing exception handler\n"); */ #endif DosUnsetExceptionHandler(&SDL_Main_xcpthand); return 1; } else { #ifdef DEBUG_BUILD /* Make stdout and stderr unbuffered! */ setbuf(stdout, NULL); setbuf(stderr, NULL); #endif /* Fire up exception handler */ #ifdef DEBUG_BUILD /* printf("[SDL DLL Initialization] : Setting exception handler\n"); */ #endif /* Set exception handler */ DosSetExceptionHandler(&SDL_Main_xcpthand); return 1; } } #endif /* __WATCOMC__ */ #elif defined(__WIN32__) && !defined(__SYMBIAN32__) #if !defined(HAVE_LIBC) || (defined(__WATCOMC__) && defined(BUILD_DLL)) /* Need to include DllMain() on Watcom C for some reason.. */ #define WIN32_LEAN_AND_MEAN #include <windows.h> BOOL APIENTRY _DllMainCRTStartup( HANDLE hModule, DWORD ul_reason_for_call, LPVOID lpReserved ) { switch (ul_reason_for_call) { case DLL_PROCESS_ATTACH: case DLL_THREAD_ATTACH: case DLL_THREAD_DETACH: case DLL_PROCESS_DETACH: break; } return TRUE; } #endif /* building DLL with Watcom C */ #endif /* OS/2 elif __WIN32__ */