* 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.

Simple DirectMedia Layer CREDITS
Thanks to everyone who made this possible, including:

* Cliff Matthews, for giving me a reason to start this project. :)
 -- Executor rocks!  *grin*

* Scott Call, for making a home for SDL on the 'Net... Thanks! :)

* The Linux Fund, C Magazine, Educational Technology Resources Inc.,
  Gareth Noyce, Jesse Pavel, Keith Kitchin, Jeremy Horvath, Thomas Nicholson,
  Hans-Peter Gygax, the Eternal Lands Development Team, Lars Brubaker,
  and Phoenix Kokido for financial contributions

* Gaëtan de Menten for writing the PHP and SQL behind the SDL website

* Tim Jones for the new look of the SDL website

* Marco Kraus for setting up SDL merchandise

* Martin Donlon for his work on the SDL Documentation Project

* Ryan Gordon for helping everybody out and keeping the dream alive. :)

* Mattias Engdegård, for help with the Solaris port and lots of other help

* Max Watson, Matt Slot, and Kyle for help with the MacOS Classic port

* Stan Shebs, for the initial Mac OS X port

* Eric Wing, Max Horn, and Darrell Walisser for unflagging work on the Mac OS X port

* Patrick Trainor, Jim Boucher, and Mike Gorchak for the QNX Neutrino port

* Carsten Griwodz for the AIX port

* Gabriele Greco, for the Amiga port

* Patrice Mandin, for the Atari port

* Hannu Viitala for the EPOC port

* Marcus Mertama for the S60 port.

* Peter Valchev for nagging me about the OpenBSD port until I got it right. :)

* Kent B Mein, for a place to do the IRIX port

* Ash, for a place to do the OSF/1 Alpha port

* David Sowsy, for help with the BeOS port

* Eugenia Loli, for endless work on porting SDL games to BeOS

* Jon Taylor for the GGI front-end

* Paulus Esterhazy, for the Visual C++ testing and libraries

* Brenda Tantzen, for Metrowerks CodeWarrior on MacOS

* Chris Nentwich, for the Hermes assembly blitters

* Michael Vance and Jim Kutter for the X11 OpenGL support

* Stephane Peter, for the AAlib front-end and multi-threaded timer idea.

* Jon Atkins for SDL_image, SDL_mixer and SDL_net documentation

* Peter Wiklund, for the 1998 winning SDL logo,
  and Arto Hamara, Steven Wong, and Kent Mein for other logo entries.

* Arne Claus, for the 2004 winning SDL logo,
  and Shandy Brown, Jac, Alex Lyman, Mikkel Gjoel, #Guy, Jonas Hartmann,
  Daniel Liljeberg,  Ronald Sowa, DocD, Pekka Jaervinen, Patrick Avella,
  Erkki Kontilla, Levon Gavalian, Hal Emerich, David Wiktorsson,
  S. Schury and F. Hufsky, Ciska de Ruyver, Shredweat, Tyler Montbriand,
  Martin Andersson, Merlyn Wysard, Fernando Ibanez, David Miller,
  Andre Bommele, lovesby.com, Francisco Camenforte Torres, and David Igreja
  for other logo entries.

* Bob Pendleton and David Olofson for being long time contributors to
  the SDL mailing list.

* Everybody at Loki Software, Inc. for their great contributions!

 And a big hand to everyone else who gave me appreciation, advice,
 and suggestions, especially the good folks on the SDL mailing list.

THANKS! :)

  -- Sam Lantinga			<slouken@libsdl.org>