Events not detected under SDL2

[sdumetz]

I have ran into it multiple times with this library (or previously with my home made equivalent).

SDL2 does detect a SDL_JOYDEVICEADDED but then no further SDL_JOYBUTTONDOWN is emitted.

It's reproductible with a minimal Arduino code pressing buttons and the following SDL code :

#include <SDL2/SDL.h>
#include <iostream>

int main(int argc, char **argv)
{
    // Notre fenêtre
    bool end = false;
    SDL_Joystick *joy;
    SDL_Event evenements;
    bool terminer(false);

    if(SDL_Init(SDL_INIT_VIDEO |SDL_INIT_JOYSTICK) < 0)
    {
        std::cout << "Error during SDL init : " << SDL_GetError() << std::endl;
        SDL_Quit();

        return -1;
    }
    SDL_JoystickEventState(SDL_ENABLE);
    for(int i=0;i<SDL_NumJoysticks();i++){
      std::cout<<"Joystick N°"<<i<<" : "<< SDL_JoystickNameForIndex(i) << std::endl;
    }
    while(!end){
      while(SDL_PollEvent(&evenements)) 
      {
        switch (evenements.type){
          case SDL_QUIT:
            /* Quit the application */
            std::cout<<"EXIT"<<std::endl;
            end = true;
            break;
          case SDL_CONTROLLERDEVICEADDED:
            std::cout<<"Controller Added"<<std::endl;
            break;
          case SDL_JOYDEVICEADDED:
            std::cout<<"Joystick Added"<<std::endl;
            break;
          case SDL_JOYBUTTONDOWN:
            std::cout<<"button "<<evenements.jbutton.button<< "Pressed"<<std::endl;
            break;
          default:
            std::cout<<"event of type:"<<evenements.type<<std::endl;
        }

      }
    }
    // On quitte la SDL
    SDL_Quit();

    return 0;
}

Compile with : g++ -lSDL2 SDL_test.cpp -o test

I've tested with debian 8.2 (SDL2 v2.0.2) and arduino Leonardo. I lack the hardware to do proper testing on other platforms / hardware.

I think it might just be a problem in SDL and I'm ready to dig into it but beforehand I'd like to be sure it's a global problem which affect "everyone".

[nenad-jalsovec]

Have you ever managed to get to the bottom of this? I ran into exactly the same issue working on a small SDL project on windows with VC++ 2017 with SDL 2.0.9. Same thing with latest SDL 2.0.12.

Joystick was initialized by the book, all other joystick events are firing properly except SDL_JOYBUTTONDOWN. Can't find any solution to this around the web. Please advise if you found a fix. Cheers!

[mcrfinch]

So a year on and I too have discovered an issue with the buttons, I'll leave it here incase its related for or helps someone else.

No button changes detected when using SDL_JoystickGetButton. Work around is to poll events as shown below (QT using VS2019 compiler).

`#define MAXBUTTON 32

bool buttonVal [MAXBUTTON] = {};

void pollButton(SDL_Joystick * controller) { //Event handler SDL_Event e;

while( SDL_PollEvent( &e ) != 0 )
{

    if(e.type == SDL_JOYBUTTONDOWN)
    {
        buttonVal[e.cbutton.button] = true;
    }
    else if(e.type == SDL_JOYBUTTONUP)
    {
        buttonVal[e.cbutton.button] = false;
    }
}
/*
for(uint8_t i = 0; i < MAXBUTTON; i++)
{
    if(SDL_JoystickGetButton(controller,i) != 0)
    {
        buttonVal[0] = true;
    }
    else
    {
        buttonVal[0] = false;
    }
}
*/

}`

[ShikyC]

I'm working on a personal project and also encountered this issue. After some preliminary testing I can confirm that only SDL_JOYDEVICEADDED and SDL_JOYDEVICEREMOVED events are detected by SDL2, while all the other inputs like SDL_JOYAXISMOTION and SDL_JOYBUTTONDOWN are not captured.

UPDATE: Found the solution. It's because the custom controller is not in the gamecontrollerdb.txt table so SDL does not know how to map your buttons and axis to its library. You need to add a new entry (with tools like SDL2 Gamepad Mapper) with your controller's GUID, name and button/axis mappings.