These were added a very long time ago and seem to serve no purpose now, as the functionality they provided is now in core Wayland protocols, current information on their usage and status is nonexistent, no modern compositor seems to support them, and the code paths are untested and subject to bit-rot at this point. It also causes duplicate symbol issues when statically linking an application to both Qt and SDL.
Emscripten was using its own, private integer in order to allocate
new SDL_JoystickIDs. SDL keeps a similar integer for allocating
joystick-ids, one which is shared across multiple joystick backends.
SDL 2.0.13 introduces a new joystick-backend, a Virtual joystick
backend, which allows for software-driven joysticks, and which is
designed to sit alongside joystick-backends that provide access to
physical joysticks.
The Emscripten and the Virtual backends were, at times, getting
allocated the same SDL_JoystickIDs, if and when both backends were used
simultaneously. This could happen if, for example, an application
was using a virtual joystick in order to drive a touch-screen
based joystick, while also supporting physical joysticks through the
Emscripten backend.
When two joysticks end up with the same SDL_JoystickID, conflicts
can occur. For example, disconnecting a physical joystick with
the same SDL_JoystickID as a virtual one, can lead to the virtual
joystick being closed, inadvertently.
This fix makes the Emscripten backend use SDL's cross-joystick-backend
integer counter, which is shared among joystick backends, for allocating
new SDL_JoystickIDs, rather than a private, Emscripten-specific
counter.
Fixes https://github.com/libsdl-org/SDL/issues/3647
When converting normalized coordinates to pixel coordinates, the valid range is 0 to (width or height) - 1, and the pixel coordinate of width or height is past the edge of the window.
Fixes https://github.com/libsdl-org/SDL/issues/2913
Pointers to static internal data need to be updated when copying events, or the cleanup code will attempt to free old stack data that went out of scope.
Existing code is erroneous, because it adds or removes dependency's ref count based on number of InitSubSystem/QuitSubSystem calls, while ref count diff should depend on number of inited or quit dependents.
Recursive approach seems to be simplest solution that guarantees proper ref count.
SDL_PollEvent(), SDL_WaitEvent(), and SDL_WaitEventTimeout() all return SDL_bool.
SDL_AddEventWatch() returns an int result code.
Also improved timeout accuracy in SDL_WaitEventTimeout()
This reverts commit e5a15f94e2.
It turns out removing this check allows mice like the ROG PUGIO II to show up as game controllers. We need to find a different way to differentiate between gaming mice and pedals.
Since these mice show up as controllers, and potentially causing games to use them instead of real controllers, we'll go ahead revert this change for now.
Reopens https://github.com/libsdl-org/SDL/issues/8227
This lets apps optionally have a handful of callbacks for their entry points instead of a single main function. If used, the actual main/SDL_main/whatever entry point will be implemented in the single-header library SDL_main.h and the app will implement four separate functions:
First:
int SDL_AppInit(int argc, char **argv);
This will be called once before anything else. argc/argv work like they always do. If this returns 0, the app runs. If it returns < 0, the app calls SDL_AppQuit and terminates with an exit code that reports an error to the platform. If it returns > 0, the app calls SDL_AppQuit and terminates with an exit code that reports success to the platform. This function should not go into an infinite mainloop; it should do any one-time startup it requires and then return.
Then:
int SDL_AppIterate(void);
This is called over and over, possibly at the refresh rate of the display or some other metric that the platform dictates. This is where the heart of your app runs. It should return as quickly as reasonably possible, but it's not a "run one memcpy and that's all the time you have" sort of thing. The app should do any game updates, and render a frame of video. If it returns < 0, SDL will call SDL_AppQuit and terminate the process with an exit code that reports an error to the platform. If it returns > 0, the app calls SDL_AppQuit and terminates with an exit code that reports success to the platform. If it returns 0, then SDL_AppIterate will be called again at some regular frequency. The platform may choose to run this more or less (perhaps less in the background, etc), or it might just call this function in a loop as fast as possible. You do not check the event queue in this function (SDL_AppEvent exists for that).
Next:
int SDL_AppEvent(const SDL_Event *event);
This will be called once for each event pushed into the SDL queue. This may be called from any thread, and possibly in parallel to SDL_AppIterate. The fields in event do not need to be free'd (as you would normally need to do for SDL_EVENT_DROP_FILE, etc), and your app should not call SDL_PollEvent, SDL_PumpEvent, etc, as SDL will manage this for you. Return values are the same as from SDL_AppIterate(), so you can terminate in response to SDL_EVENT_QUIT, etc.
Finally:
void SDL_AppQuit(void);
This is called once before terminating the app--assuming the app isn't being forcibly killed or crashed--as a last chance to clean up. After this returns, SDL will call SDL_Quit so the app doesn't have to (but it's safe for the app to call it, too). Process termination proceeds as if the app returned normally from main(), so atexit handles will run, if your platform supports that.
The app does not implement SDL_main if using this. To turn this on, define SDL_MAIN_USE_CALLBACKS before including SDL_main.h. Defines like SDL_MAIN_HANDLED and SDL_MAIN_NOIMPL are also respected for callbacks, if the app wants to do some sort of magic main implementation thing.
In theory, on most platforms these can be implemented in the app itself, but this saves some #ifdefs in the app and lets everyone struggle less against some platforms, and might be more efficient in the long run, too.
On some platforms, it's possible this is the only reasonable way to go, but we haven't actually hit one that 100% requires it yet (but we will, if we want to write a RetroArch backend, for example).
Using the callback entry points works on every platform, because on platforms that don't require them, we can fake them with a simple loop in an internal implementation of the usual SDL_main.
The primary way we expect people to write SDL apps is with SDL_main, and this is not intended to replace it. If the app chooses to use this, it just removes some platform-specific details they might have to otherwise manage, and maybe removes a barrier to entry on some future platform.
Fixes#6785.
Reference PR #8247.
