* 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.

  =================================================================
  Patch version 0.9 of SDL(Simple DirectMedia Layer) for Nano-X API
  =================================================================
  
  Authors: Hsieh-Fu Tsai, clare@setabox.com
           Greg Haerr, greg@censoft.com

  This patch is against SDL version 1.2.4.
  It enhances previous patch 0.8 by providing direct framebuffer
  access as well as dynamic hardware pixel type support, not
  requiring a compile-time option setting for different framebuffer
  modes.
  Tested against Microwindows version 0.89pre9.

  Older Microwindows versions
  ===========================
  If running on a version older than Microwindows 0.89pre9,
  the following items might need to be patched in Microwindows.

  1. Patch src/nanox/client.c::GrClose()
  It fixes the client side GrClose(). In the original version, 
  GrOpen() can only be called once. When the GrOpen() is called at 
  the second time, the program will terminate. In order to prevent
  this situation, we need to insert "nxSocket = -1" after 
  "close(nxSocket)" in GrClose(). If you do not have this problem,
  you may skip this step. 

  2. Patch src/nanox/clientfb.c to return absolute x,y coordinates
  when using GrGetWindowFBInfo().  Copy the version 0.89pre9
  of src/nanox/clientfb.c to your system, or configure
  using --disable-nanox-direct-fb.

  =============
  Quick Install 
  =============

  1. ./configure --disable-video-x11 --disable-video-fbcon \ 
       --enable-video-nanox \ 
       --with-nanox-pixel-type=[rgb/0888/888/565/555/332/pal] 
  2. make clean 
  3. make 
  4. make install (as root) 

  ============
  Nitty-gritty 
  ============

  --enable-nanox-direct-fb       Use direct framebuffer access
  --enable-nanox-debug           Show debug messages 
  --enable-nanox-share-memory    Use shared-memory to speed up 

  When running multi-threaded applications using SDL, such
  as SMPEG, set THREADSAFE=Y in Microwindows' config file,
  to enable GrXXX() system call critical section support.

  =============================================
  Some programs can be used to test this patch. 
  =============================================

  1. http://www.cs.berkeley.edu/~weimer/atris (a tetris-like game) 
  2. http://www.libsdl.org/projects/newvox/
  3. http://www.libsdl.org/projects/xflame/
  4. http://www.libsdl.org/projects/optimum/ 
  5. http://www.gnugeneration.com/software/loop/ 
  6: http://www.lokigames.com/development/smpeg.php3 (SMPEG version 0.4.4)

  =========
  Todo List 
  =========

  1. Create hardware surface
  2. Create YUVOverlay on hardware
  3. Use OpenGL
  4. Gamma correction
  5. Hide/Change mouse pointer
  6. Better window movement control with direct fb access
  7. Palette handling in 8bpp could be improved

  =====================
  Supporting Institutes
  =====================
  
  Many thanks to go to Setabox Co., Ltd. and CML (Communication and
  Multimedia Laboratory, http://www.cmlab.csie.ntu.edu.tw/) in the 
  Department of Computer Science and Information Engineering of 
  National Taiwan University for supporting this porting project.
  
  Century Embedded Technologies (http://embedded.censoft.com)
  for this patch.

  ===================
  Contact Information
  ===================

  Welcome to give me any suggestion and to report bugs.
  My e-mail address : clare@setabox.com or niky@cmlab.csie.ntu.edu.tw
                      or greg@censoft.com