Turn your joypad to a mouse

compiling.md

cc jm.c -lxdo -lSDL2 -lm -o jm -O3
./jm

Only tested with an Xbox 360 Wireless Controller.

Default bindings:

• Left joystick - move cursor
• Right joystick - scroll
• A - left click
• X - right click
• B - middle click
• triggers
  • left - slow down
  • right - speed up
  • the harder you press the stronger the effect
• Xbox logo - quit the emulator

jm.c

/* jm - joystick to mouse */

#include <math.h>
#include <stdio.h>
#include <unistd.h>

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

#define DEADZONE_X_MIN  -0.2
#define DEADZONE_X_MAX  0.2
#define DEADZONE_Y_MIN  -0.2
#define DEADZONE_Y_MAX  0.2
#define SCROLL_UP(x)    x < -0.5
#define SCROLL_DOWN(x)  x > 0.5
#define SPEED_BASE      10.0
#define SPEED_DEC       8.0
#define SPEED_INC       20.0

#define BUTTON_LMB      0
#define BUTTON_MMB      1
#define BUTTON_RMB      2
#define BUTTON_MODE     5
#define BUTTON_QUIT     8

int main(void) {
  xdo_t *xdo;
  SDL_Joystick *js;

  SDL_Init(SDL_INIT_JOYSTICK);

  xdo = xdo_new(NULL);
  if (SDL_NumJoysticks() > 0) {
    js = SDL_JoystickOpen(0);
  }

  int end = 0;
  int frame = 0;
  while (!end) {
    SDL_JoystickUpdate();

    #ifdef JM_DEBUG
    printf("AXES    ");
    for (int i = 0; i < SDL_JoystickNumAxes(js); ++i) {
      double x = (double)SDL_JoystickGetAxis(js, i) / 32768;
      printf("[%i: %f] ", i, x);
    }
    printf(" BUTTONS ");
    for (int i = 0; i < SDL_JoystickNumButtons(js); ++i) {
      int x = SDL_JoystickGetButton(js, i);
      printf("[%i: %i]", i, x);
    }
    printf("\n");
    #endif

    /* events */
    SDL_Event event;
    while (SDL_PollEvent(&event)) {
      switch (event.type) {
        case SDL_JOYBUTTONDOWN:
        case SDL_JOYBUTTONUP: {
          SDL_JoyButtonEvent btn_event = event.jbutton;
          int mouse_button = 0;
          switch (btn_event.button) {
          case BUTTON_LMB: mouse_button = 1; break;
          case BUTTON_MMB: mouse_button = 2; break;
          case BUTTON_RMB: mouse_button = 3; break;
          }
          if (mouse_button != 0) {
            if (btn_event.state == SDL_PRESSED) {
              xdo_mouse_down(xdo, CURRENTWINDOW, mouse_button);
            } else {
              xdo_mouse_up(xdo, CURRENTWINDOW, mouse_button);
            }
          }
        } break;
      }
    }

    /* mouse movement */
    double x0 = (double)SDL_JoystickGetAxis(js, 0) / 32768;
    double y0 = (double)SDL_JoystickGetAxis(js, 1) / 32768;
    double x1 = (double)SDL_JoystickGetAxis(js, 3) / 32768;
    double y1 = (double)SDL_JoystickGetAxis(js, 4) / 32768;
    double z0 = ((double)SDL_JoystickGetAxis(js, 2) / 32768 + 1.0) / 2.0;
    double z1 = ((double)SDL_JoystickGetAxis(js, 5) / 32768 + 1.0) / 2.0;

    double sensitivity = SPEED_BASE - z0 * SPEED_DEC + z1 * SPEED_INC;
    if (x0 < DEADZONE_X_MIN || x0 > DEADZONE_X_MAX) {
      xdo_move_mouse_relative(xdo, (int)round(x0 * sensitivity), 0);
    }
    if (y0 < DEADZONE_X_MIN || y0 > DEADZONE_Y_MAX) {
      xdo_move_mouse_relative(xdo, 0, (int)round(y0 * sensitivity));
    }

    // printf("%i  %i\n", frame % 10, (int)(y1 * 5));
    if ((int)(1 / y1 * 3) != 0) {
      if (frame % (int)(1 / y1 * 3) == 1) {
        if (SCROLL_UP(y1)) {
          xdo_click_window(xdo, CURRENTWINDOW, 4);
        }
        if (SCROLL_DOWN(y1)) {
          xdo_click_window(xdo, CURRENTWINDOW, 5);
        }
      }
    }

    /* buttons */
    if (SDL_JoystickGetButton(js, BUTTON_QUIT)) {
      end = 1;
    }

    ++frame;
    usleep(16666);
  }

  SDL_JoystickClose(js);
  SDL_Quit();
  xdo_free(xdo);
}