* 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.

Using SDL under Windows with the OpenWatcom compiler
====================================================

Prerequisites
-------------

I have done the port under Windows XP Home with SP2 installed. Windows
2000 should also be working. I'm not so sure about ancient Windows NT,
since only DirectX 3 is available there. Building should be possible,
but running the compiled applications will probalbly fail with
SDL_VIDEODRIVER=directx. The windib driver should work, though.

To compile and use the SDL with Open Watcom you will need the following:
- Open Watcom compiler. I used version 1.5. The environment variables
  PATH, WATCOM and INCLUDE need to be set appropriately - please consult
  the OpenWatcom documentation and instructions given during the
  installation of the compiler.
  My setup looks like this in owvars.bat:
    set WATCOM=C:\watcom
    set INCLUDE=%WATCOM%\h;%WATCOM%\h\nt
    set PATH=%PATH%;%WATCOM%\binnt;%WATCOM%\binw
- A fairly recent DirectX SDK. The original unmodified DX8 SDK works, as
  well as the minimal DirectX 7 SDK from the Allegro download site
  (<http://alleg.sourceforge.net/files/dx70_min.zip>).
- The SDL sources from Subversion
- The file Watcom-Win32.zip (now available in Subversion)


Building the Library
--------------------

1) In the SDL base directory extract the archive Watcom-Win32.zip. This
   creates a subdirectory named 'watcom'.
2) The makefile expects the environment variable DXDIR to be set to the
   base directory of a DirectX SDK. I have tried a stock DX8 SDK from
   Microsoft as well as the minimal DirectX 7 SDK from the Allegro
   download site.
   You can also edit the makefile directly and hard code your path to
   the SDK on your system.
   I have this in my setup:
     set DXDIR=D:\devel\DX8_SDK
3) Enter the watcom directory and run
     wmake sdl
4) All tests from the test directory are working and can be built by
   running
     wmake tests

Notes:

 The makefile offers some options to tweak the way the library is built.
 You have at your disposal the option to build a static (default)
 library, or a DLL (with tgt=dll). You can also choose whether to build
 a Release (default) or a Debug version (with build=debug) of the tests
 and library. Please consult the usage comment at the top of the
 makefile for usage instructions.

 If you specify a test target (i.e. 'wmake tests' for all tests, or
 selected targets like 'wmake testgl testvidinfo testoverlay2'), the
 tests are always freshly compiled and linked. This is done to
 minimise hassle when switching between library versions (static vs.
 DLL), because they require subtly different options.
 Also, the test executables are put directly into the test directory,
 so they can find their data files. The clean target of the makefile
 removes the test executables and the SDL.dll file from the test
 directory.

 To use the library in your own projects with Open Watcom, you can use
 the way the tests are built as base of your own build environment.

 The library can also be built with the stack calling convention of the
 compiler (-6s instead of -6r).


Test applications
-----------------

I've tried to make all tests work. The following table gives an overview
of the current status.

 Testname        Status
~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
checkkeys       +
graywin         +
loopwave        +
testalpha       +
testbitmap      +
testdyngl       +
testerror       +
testfile        +
testgamma       +
testgl          +
testhread       +
testiconv       - (all failed)
testkeys        +
testlock        +
testoverlay     + (needs 'set SDL_VIDEODRIVER=directx')
testoverlay2    + (needs 'set SDL_VIDEODRIVER=directx')
testpalette     +
testplatform    +
testsem         +
testsprite      +
testtimer       +
testver         +
testvidinfo     +
testwin         ? (fading doesn't seem right)
testwm          +
torturethread   +
testcdrom       +
testjoystick    not tested
threadwin       +
testcursor      +


TODO
----

There is room for further improvement:
- Test joystick functionality.
- Investigate fading issue in 'testwin' test.
- Fix the UTF-8 support.
- Adapt the makefile/object file list to support more target systems
- Use "#pragma aux" syntax for the CPU info functions.


Questions and Comments
----------------------

Please direct any questions or comments to me:  <mailto:macpete@gmx.de>

   Happy Coding!

   Marc Peter