The code is now reliant on SDL_PrivateJoystickAdded() and SDL_PrivateJoystickRemoved() being called correctly when devices are added or removed on Windows
Edward Rudd
Device: Logitech Rumble Gamepad F510 in Xinput mode.
Upon opening the joystick the values of the axes are queried via PollAllValues are not actually set on the device all the time.
This can easily be seen in the testjoystick or testgamecontroller test programs,as the testjoystick shows all axes in the center until one 'tickles' the triggers., and the testgamecontroller will show the triggers as 'on' until on 'tickles' the triggers.
Upon further research the culprit is the SDL_HINT_JOYSTICK_ALLOW_BACKGROUND_EVENTS hint. In the default value events are ignored until there is an active window, Thus in cases where the joystick system is initialized and controllers opened before the initial window is created & focuses, the initial values will be incorrect.
Here is my current workaround in the game I'm working on porting..
SDL_SetHint(SDL_HINT_JOYSTICK_ALLOW_BACKGROUND_EVENTS, "1");
SDL_GameController* gamepad = SDL_GameControllerOpen(index);
SDL_SetHint(SDL_HINT_JOYSTICK_ALLOW_BACKGROUND_EVENTS, "0");
Fixed a case where partial trigger pull could be bound to another button
There is a fundamental problem not resolved by this commit:
Some controllers have axes (triggers, pedals, etc.) that don't start at zero, but we're guaranteed that if we get a value that it's correct. For these controllers, the current code works, where we take the first value we get and use that as the zero point and generate axis motion starting from that point on.
Other controllers have digital axes (D-pad) that assume a zero starting point, and the first value we get is the min or max axis value when the D-pad is moved. For these controllers, the current code thinks that the zero point is the axis value after the D-pad motion and this doesn't work.
My hypothesis is that the first class of devices is more common and that we should solve for that, and add an exception to SDL_JoystickAxesCenteredAtZero() as needed for the second class of devices.
This adds support for all XInput devices, exposed through the SDL joystick API.
The button and axis reporting for XInput devices has been changed to match DirectInput and other platforms.
The game controller xinput mapping has been updated so this change is seamless.
There is a new hint, SDL_HINT_XINPUT_USE_OLD_JOYSTICK_MAPPING, for any applications that have hardcoded the old xinput button and axis set. This hint will be removed in SDL 2.1.
It was simpler to just have the polling (actually: hotplug detection)
functions return immediately if it's not an appropriate time to poll.
Note that previously, if any joystick/controller was opened, we would poll
every time anyhow, skipping this function.
