Wayland can expose displays in any arbitrary order, and doesn't have the native concept of a primary display. However, there are games that presume that the first listed display is the primary, which can lead to problems if that output isn't necessarily the ideal one, as they may use that display to build a resolution list or as the default fullscreen output. This sorts displays by position, then attempts to find the primary display, first by querying the explicit ordering hint, then the GNOME DBus property, then tries to determine the 'best' display according to the criteria that is generally ideal for games and media playback.
The makes the list of displays deterministic, as long as the desktop configuration remains static, with a reasonably appropriate one prioritized as primary, even if there is no explicit way to retrieve the primary display. In the case where a user has a particularly esoteric physical display configuration, the new hint enables explicitly overriding the sorting and selection logic, allowing the entire display order to be customized, if necessary.
My simplification of the conditions for including SDL_main_impl.h
had one problem: I forgot that SDL_main_impl.h must be included
even on Android when SDL_MAIN_USE_CALLBACKS is used, because then a
SDL_main() function that makes sure the callbacks get called is needed,
and that function is implemented in SDL_main_impl.h
But OTOH, even when SDL_MAIN_USE_CALLBACKS is used, SDL_main_impl.h
should not implement a standard `int main(...)` function on Android
(because there the SDL-using native code is compiled as a library and
the entry point is in SDLActivity.java, which calls SDL_main()
in said library).
So the check for platforms that don't have *any* native main function
but just SDL_main() called from the outside should be handled in
SDL_main_impl.h, so both the normal and the callback case can avoid
generating a standard main() in the same way.
To do this, SDL_MAIN_EXPORTED is defined for platforms like Android,
where the real entry point (main() function) is outside of the code
that uses SDL, so
- SDL_main() must be visibly exported with SDL_DECLSPEC, so the outside
code can call it
- SDL_main_impl.h must not implement a "real" main() function
Another small change based on this is defining SDLMAIN_DECLSPEC
at a more general place.
If another platform like Android (where the entry point is somewhere
else entirely, possibly implemented in a different programming language)
turns up, defining SDL_MAIN_NEEDED (so the users main() is renamed
to SDL_main()) and SDL_MAIN_EXPORTED should be all that's needed on the
SDL_main.h side - and if not then at least the implementation is
cleaner and clearer now, IMHO.
fixes#11162
SDL_DelayNS() now passes through to the high precision OS delay function, and SDL_DelayPrecise() tries to busy wait to get as close as possible to the desired wait time.
Fixes https://github.com/libsdl-org/SDL/issues/11141
This includes both wasm64 and wasm32 when addressing more than 2gb of memory.
Fixes: #9052
(Manually cherry-picked from 3deb07ea395373204462130c1e062bc1f71fe060.)
If WinRT returns after all, or a similarly bad platforms turns up,
the code can still be found in the git history.
But keep in mind that it then will have to be added *before* the
#if ( defined(SDL_MAIN_USE_CALLBACKS) || defined(SDL_MAIN_NEEDED) ...
case for platforms that support plain C to work correctly
Basically all platforms where SDL_main.h renames main() to SDL_main()
use the platform-specific main() (or WinMain() or whatever)
implementations in SDL_main_impl.h - and that renaming is enabled with:
#if defined(SDL_MAIN_NEEDED) || defined(SDL_MAIN_AVAILABLE) \
|| defined(SDL_MAIN_USE_CALLBACKS)
#define main SDL_main
#endif
The only exception is Android, where main() *is* renamed, but
SDL_main_impl.h isn't used, because SDL_main() is called from Java.
So I think it's cleaner and less error-prone (for adding additional
platforms that need SDL_main() in the future), to use the same check
for including SDL_main_impl.h as is used for `#define main SDL_main`
and only list the exceptions (currently Android) there explicitly.
If new platforms like Android turn up, they can easily be added there
by inserting "|| defined(SDL_PLATFORM_WEIRDPLATFORM)" right next
to the Android check.
See also https://github.com/libsdl-org/SDL/issues/11068#issuecomment-2399907535
Updates some documentation to correspond with changes made since it was originally written, clarifies some function behavior, and includes some assorted typo fixes.
