Mercurial > sdl-ios-xcode
view src/hermes/HeadX86.h @ 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 | bb5ace455586 |
children | 782fd950bd46 c121d94672cb 39b9405d3cb6 |
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/* Header definitions for the x86 routines for the HERMES library Copyright (c) 1998 Christian Nentwich (brn@eleet.mcb.at) This source code is licensed under the GNU LGPL Please refer to the file COPYING.LIB contained in the distribution for licensing conditions */ #ifndef __HERMES_HEAD_X86__ #define __HERMES_HEAD_X86__ #ifdef X86_ASSEMBLER /* If you can't stand IFDEFS, then close your eyes now, please :) */ /* Ok, we start with normal function definitions */ #ifdef __cplusplus extern "C" { #endif void STACKCALL ConvertX86(HermesConverterInterface *); void STACKCALL ClearX86_32(HermesClearInterface *); void STACKCALL ClearX86_24(HermesClearInterface *); void STACKCALL ClearX86_16(HermesClearInterface *); void STACKCALL ClearX86_8(HermesClearInterface *); int STACKCALL Hermes_X86_CPU(); void ConvertX86p32_32BGR888(); void ConvertX86p32_32RGBA888(); void ConvertX86p32_32BGRA888(); void ConvertX86p32_24RGB888(); void ConvertX86p32_24BGR888(); void ConvertX86p32_16RGB565(); void ConvertX86p32_16BGR565(); void ConvertX86p32_16RGB555(); void ConvertX86p32_16BGR555(); void ConvertX86p32_8RGB332(); void ConvertX86p16_32RGB888(); void ConvertX86p16_32BGR888(); void ConvertX86p16_32RGBA888(); void ConvertX86p16_32BGRA888(); void ConvertX86p16_24RGB888(); void ConvertX86p16_24BGR888(); void ConvertX86p16_16BGR565(); void ConvertX86p16_16RGB555(); void ConvertX86p16_16BGR555(); void ConvertX86p16_8RGB332(); void CopyX86p_4byte(); void CopyX86p_3byte(); void CopyX86p_2byte(); void CopyX86p_1byte(); void ConvertX86pI8_32(); void ConvertX86pI8_24(); void ConvertX86pI8_16(); extern int ConvertX86p16_32RGB888_LUT_X86[512]; extern int ConvertX86p16_32BGR888_LUT_X86[512]; extern int ConvertX86p16_32RGBA888_LUT_X86[512]; extern int ConvertX86p16_32BGRA888_LUT_X86[512]; #ifdef __cplusplus } #endif /* Now fix up the ELF underscore problem */ #if defined(__ELF__) && defined(__GNUC__) #ifdef __cplusplus extern "C" { #endif extern int _Hermes_X86_CPU(); extern void _ConvertX86(HermesConverterInterface *); extern void _ConvertX86p32_32BGR888(); extern void _ConvertX86p32_32RGBA888(); extern void _ConvertX86p32_32BGRA888(); extern void _ConvertX86p32_24RGB888(); extern void _ConvertX86p32_24BGR888(); extern void _ConvertX86p32_16RGB565(); extern void _ConvertX86p32_16BGR565(); extern void _ConvertX86p32_16RGB555(); extern void _ConvertX86p32_16BGR555(); extern void _ConvertX86p32_8RGB332(); extern void _ConvertX86p16_16BGR565(); extern void _ConvertX86p16_16RGB555(); extern void _ConvertX86p16_16BGR555(); extern void _ConvertX86p16_8RGB332(); #define Hermes_X86_CPU _Hermes_X86_CPU #define ConvertX86 _ConvertX86 #define ConvertX86p32_32BGR888 _ConvertX86p32_32BGR888 #define ConvertX86p32_32RGBA888 _ConvertX86p32_32RGBA888 #define ConvertX86p32_32BGRA888 _ConvertX86p32_32BGRA888 #define ConvertX86p32_24RGB888 _ConvertX86p32_24RGB888 #define ConvertX86p32_24BGR888 _ConvertX86p32_24BGR888 #define ConvertX86p32_16RGB565 _ConvertX86p32_16RGB565 #define ConvertX86p32_16BGR565 _ConvertX86p32_16BGR565 #define ConvertX86p32_16RGB555 _ConvertX86p32_16RGB555 #define ConvertX86p32_16BGR555 _ConvertX86p32_16BGR555 #define ConvertX86p32_8RGB332 _ConvertX86p32_8RGB332 #define ConvertX86p16_16BGR565 _ConvertX86p16_16BGR565 #define ConvertX86p16_16RGB555 _ConvertX86p16_16RGB555 #define ConvertX86p16_16BGR555 _ConvertX86p16_16BGR555 #define ConvertX86p16_8RGB332 _ConvertX86p16_8RGB332 #ifdef __cplusplus } #endif #endif /* ELF & GNU */ /* Make it run with WATCOM C */ #ifdef __WATCOMC__ #pragma warning 601 9 #pragma aux Hermes_X86_CPU "_*" #pragma aux ConvertX86 "_*" modify [EAX EBX ECX EDX ESI EDI] #pragma aux ClearX86_32 "_*" modify [EAX EBX ECX EDX ESI EDI] #pragma aux ClearX86_24 "_*" modify [EAX EBX ECX EDX ESI EDI] #pragma aux ClearX86_16 "_*" modify [EAX EBX ECX EDX ESI EDI] #pragma aux ClearX86_8 "_*" modify [EAX EBX ECX EDX ESI EDI] #pragma aux ConvertX86p32_32BGR888 "_*" #pragma aux ConvertX86p32_32RGBA888 "_*" #pragma aux ConvertX86p32_32BGRA888 "_*" #pragma aux ConvertX86p32_24RGB888 "_*" #pragma aux ConvertX86p32_24BGR888 "_*" #pragma aux ConvertX86p32_16RGB565 "_*" #pragma aux ConvertX86p32_16BGR565 "_*" #pragma aux ConvertX86p32_16RGB555 "_*" #pragma aux ConvertX86p32_16BGR555 "_*" #pragma aux ConvertX86p32_8RGB332 "_*" #pragma aux ConvertX86p16_32RGB888 "_*" #pragma aux ConvertX86p16_32BGR888 "_*" #pragma aux ConvertX86p16_32RGBA888 "_*" #pragma aux ConvertX86p16_32BGRA888 "_*" #pragma aux ConvertX86p16_24RGB888 "_*" #pragma aux ConvertX86p16_24BGR888 "_*" #pragma aux ConvertX86p16_16BGR565 "_*" #pragma aux ConvertX86p16_16RGB555 "_*" #pragma aux ConvertX86p16_16BGR555 "_*" #pragma aux ConvertX86p16_8RGB332 "_*" #pragma aux CopyX86p_4byte "_*" #pragma aux CopyX86p_3byte "_*" #pragma aux CopyX86p_2byte "_*" #pragma aux CopyX86p_1byte "_*" #pragma aux ConvertX86pI8_32 "_*" #pragma aux ConvertX86pI8_24 "_*" #pragma aux ConvertX86pI8_16 "_*" #pragma aux ConvertX86p16_32RGB888_LUT_X86 "_*" #pragma aux ConvertX86p16_32BGR888_LUT_X86 "_*" #pragma aux ConvertX86p16_32RGBA888_LUT_X86 "_*" #pragma aux ConvertX86p16_32BGRA888_LUT_X86 "_*" #endif /* __WATCOMC__ */ #endif /* X86_ASSEMBLER */ #endif