sdl_gamepad.c and vo_sdl.c both have their own event loops and run in
separate threads. They don't know of each other (and shouldn't). Since
SDL only has one global event loop (why didn't they fix this in SDL2?),
these obviously clash. The actual behavior is relatively subtle, which
event being randomly dispatched to either of the threads.
This is very regrettable. Very.
Work this around. "Fortunately" SDL exposes its global state to some
degree. SDL_WasInit() returns whether a "subsystem" was initialized, and
you could say the one who initialized it owns it. Both SDL_INIT_VIDEO
and SDL_INIT_GAMECONTROLLER implicitly enable SDL_INIT_EVENTS, and the
event loop is indeed the resource that cannot be shared.
Unfortunately, this is still racy, since SDL_InitSubSystem is a second
call, and succeeds if the subsystem is already initialized (increases a
refcount I think). But good enough. Blame SDL for everything.
(I think I made this commit message too long. Nobody cares even.)
Fixes: #7085
The code is very basic:
- only handles gamepads, could be extended for generic joysticks in the
future.
- only has button mappings for controllers natively supported by SDL2.
I heard more can be added through env vars, there's also ways to load
mappings from text files, but I'd rather not go there yet. Common ones
like Dualshock are supported natively.
- analog buttons (TRIGGER and AXIS) are mapped to discrete buttons using an
activation threshold.
- only supports one gamepad at a time. the feature is intented to use
gamepads as evolved remote controls, not play multiplayer games in mpv :)
wm4
Stefano Pigozzi