list devices and events of key and button release

devices.c

#include <X11/Xlib.h>
#include <X11/extensions/XInput.h>
#include <stdio.h>

/**
 * libs needed: libx11-dev libxi-dev
 * $ gcc devices.c -o devices -lX11 -lXi && ./devices
 */

static int key_release_type    = -1;
static int button_release_type = -1;

int main (int argc, char **argv) {
  XDevice         *device;
  XInputClassInfo *ici;
  XEventClass     e_list[20];
  XEvent          e;

  int n_devices, i, j, n = 0;

  Display *display     = XOpenDisplay(NULL);
  unsigned long screen = DefaultScreen(display);
  Window w_root        = RootWindow(display, screen);
  XDeviceInfo *devices = XListInputDevices(display, &n_devices);

  for (i = 0; i < n_devices; ++i) {
    if (devices[i].type < 1)
      continue;

    printf(
      "[i] device, name: %s, id: %d, type: %d\n",
      devices[i].name, (int) devices[i].id, (int) devices[i].type
    );

    // open device
    device = XOpenDevice(display, devices[i].id);

    // list device events
    if (device->num_classes > 0) {
      for (ici = device->classes, j=0; j < device->num_classes; ++ici, ++j) {
        if (ici->input_class == KeyClass) {
          printf("  ->  device has key events, id: %d\n", (int) devices[i].id);
          DeviceKeyRelease(device, key_release_type, e_list[n]); ++n;
        } else if (ici->input_class == ButtonClass) {
          printf("  ->  device has button events, id: %d\n", (int) devices[i].id);
          DeviceButtonRelease(device, button_release_type, e_list[n]); ++n;
        }
      }
    }
  }

  XFreeDeviceList(devices);

  printf("[i] number of devices: %d, events: %d\n", n_devices, n);

  if (XSelectExtensionEvent(display, w_root, e_list, n)) {
    printf("error selecting events\n");
  }

  setvbuf(stdout, NULL, _IOLBF, 0);

  while (1) {
    XNextEvent(display, &e);

    if (e.type == key_release_type) {
      XDeviceKeyEvent *key = (XDeviceKeyEvent *) &e;
      printf("[e] key release %d \n", key->keycode);
    } else if (e.type == button_release_type) {
      XDeviceButtonEvent *button = (XDeviceButtonEvent *) &e;
      printf("[e] button release %d \n", button->button);
    }
  }

  XFree(display);
  return 0;
}

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