libspnav example controlling mouse using spaceball (uinput)

build.sh

# build with spnav
gcc simple.c `pkg-config spnav --cflags --libs` -lm -O3 -flto -osimple_uinput
# build without spnav
gcc simple.c spnav.c proto.c -O3 -lm -flto -osimple_uinput

simple.c

/* libspnav example
 * Control mouse using spaceball (X, Z axis) + 2D mouse wheel (RX, RZ axis)
 */
#include "spnav.h"
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>

#include <fcntl.h>
#include <linux/uinput.h>
#include <stdbool.h>
#include <string.h>
#include <unistd.h>

void print_dev_info(void);

static int fd; // uinput fd

void sig(int s) {
  spnav_close();
  ioctl(fd, UI_DEV_DESTROY);
  close(fd);
  exit(0);
}

void emit(int fd, int type, int code, int val) {
  struct input_event ie;

  ie.type = type;
  ie.code = code;
  ie.value = val;
  /* timestamp values below are ignored */
  ie.time.tv_sec = 0;
  ie.time.tv_usec = 0;

  write(fd, &ie, sizeof(ie));
}

int main(void) {

  struct uinput_setup usetup;

  const int button_keys[12] = {
      KEY_F13, // 1
      KEY_F14, // 2
      KEY_F15, // 3
      KEY_F16, // 4
      KEY_F17, // 5
      KEY_F18, // 6
      KEY_F19, // 7
      KEY_F20, // 8
      KEY_F21, // 9
      KEY_F22, // A
      KEY_F23, // B
      BTN_LEFT // C
  };

  fd = open("/dev/uinput", O_WRONLY | O_NONBLOCK);
  if (fd < 0) {
    perror("Can't open /dev/uinput");
    return 1;
  }

  /* enable button events */
  ioctl(fd, UI_SET_EVBIT, EV_KEY);
  for (int i = 0; i < 12; i++)
    ioctl(fd, UI_SET_KEYBIT, button_keys[i]);

  /* enable motion events */
  ioctl(fd, UI_SET_EVBIT, EV_REL);
  ioctl(fd, UI_SET_RELBIT, REL_X);
  ioctl(fd, UI_SET_RELBIT, REL_Y);
  ioctl(fd, UI_SET_RELBIT, REL_HWHEEL_HI_RES);
  ioctl(fd, UI_SET_RELBIT, REL_WHEEL_HI_RES);

  spnav_event sev;

  signal(SIGINT, sig);

  if (spnav_open() == -1) {
    fprintf(stderr, "failed to connect to spacenavd\n");
    return 1;
  }

  print_dev_info();
  memset(&usetup, 0, sizeof(usetup));
  usetup.id.bustype = BUS_USB;
  usetup.id.vendor = 0x1234;  /* sample vendor */
  usetup.id.product = 0x5678; /* sample product */
  spnav_dev_name(usetup.name, sizeof usetup.name);

  spnav_sensitivity(0.25);

  ioctl(fd, UI_DEV_SETUP, &usetup);
  ioctl(fd, UI_DEV_CREATE);

  /* spnav_wait_event() and spnav_poll_event(), will silently ignore any
   * non-spnav X11 events.
   *
   * If you need to handle other X11 events you will have to use a regular
   * XNextEvent() loop, and pass any ClientMessage events to spnav_x11_event,
   * which will return the event type or zero if it's not an spnav event (see
   * spnav.h).
   */
  bool idle = true;
  while (true) {
    int result;
    if (idle)
      result = spnav_wait_event(&sev);
    else
      result = spnav_poll_event(&sev);

    if (!result) {
      if (idle)
        break;
      sev.type = SPNAV_EVENT_MOTION; // repeat last motion every 10ms
      usleep(10 * 1000);

      result = spnav_poll_event(&sev);
    }

    if (sev.type == SPNAV_EVENT_MOTION) {
      // printf("got motion event: t(%d, %d, %d) ", sev.motion.x, sev.motion.y,
      // sev.motion.z); printf("r(%d, %d, %d)\n", sev.motion.rx, sev.motion.ry,
      // sev.motion.rz);
      if (sev.motion.x || sev.motion.y || sev.motion.z || sev.motion.rx ||
          sev.motion.ry || sev.motion.rz)
        idle = false;
      else
        idle = true;
      emit(fd, EV_REL, REL_X, sev.motion.x);
      emit(fd, EV_REL, REL_Y, -sev.motion.z);
      emit(fd, EV_REL, REL_WHEEL_HI_RES, -sev.motion.rx);
      emit(fd, EV_REL, REL_HWHEEL_HI_RES, sev.motion.rz);
      emit(fd, EV_SYN, SYN_REPORT, 0);

    } else { /* SPNAV_EVENT_BUTTON */
      printf("got button %s event b(%d)\n",
             sev.button.press ? "press" : "release", sev.button.bnum);
      if (sev.button.bnum < 12) {
        emit(fd, EV_KEY, button_keys[sev.button.bnum], sev.button.press);
        emit(fd, EV_SYN, SYN_REPORT, 0);
      }
    }
  }

  spnav_close();

  ioctl(fd, UI_DEV_DESTROY);
  close(fd);

  return 0;
}

void print_dev_info(void) {
  int proto;
  char buf[256];

  if ((proto = spnav_protocol()) == -1) {
    fprintf(stderr, "failed to query protocol version\n");
    return;
  }
  printf("spacenav AF_UNIX protocol version: %d\n", proto);

  spnav_client_name("simple example");

  if (proto >= 1) {
    spnav_dev_name(buf, sizeof buf);
    printf("Device: %s\n", buf);
    spnav_dev_path(buf, sizeof buf);
    printf("Path: %s\n", buf);
    printf("Buttons: %d\n", spnav_dev_buttons());
    printf("Axes: %d\n", spnav_dev_axes());
  }

  putchar('\n');
}