An example of sending a synthetic GdkEvent

readme.md

What this

I picked this up from this email thread from 2004 and edited it enough to compile on recent GDK/GTK. Thanks to Tommi Komulainen and Juhana Sadeharju!

Context for why I'm reading these things: anko/hudkit#3

Run it

$ make
[ ... warnings and deprecation notices, but it compiles ... ]
$ ./program

main.c

#include <gtk/gtk.h>
#include <gdk/gdkkeysyms.h>

static gboolean
on_timeout (gpointer user_data)
{
  GtkWidget *widget = user_data;
  GdkKeymapKey *keys;
  gint n_keys;

  if (gdk_keymap_get_entries_for_keyval (gdk_keymap_get_default (),
                                         'o', &keys, &n_keys))
    {
      guint16 hardware_keycode;
      GdkEventKey *event;

      /* we can pick any hardware_keycode that generates GDK_o */
      hardware_keycode = keys[0].keycode;
      g_free (keys);

      /* synthesize Alt+O key press */
      event = (GdkEventKey*)gdk_event_new (GDK_KEY_PRESS);
      event->window = gtk_widget_get_window(widget);
      event->state = GDK_MOD1_MASK;               /* Alt */
      event->hardware_keycode = hardware_keycode; /*  +O */

      /* these are optional but possibly nice to have */
      event->keyval = gdk_unicode_to_keyval ('o');
      event->length = 1;
      event->string = g_strdup ("o");

      /* the rest are no-ops */
      event->send_event = FALSE;      /* seems unused except for dnd */
      event->time = GDK_CURRENT_TIME;

      gtk_main_do_event (event);
      gdk_event_free (event);
    }

  return FALSE;
}

static gboolean
on_key_press_event (GtkWidget *widget, GdkEventKey *event)
{
  g_print ("send_event=%d, state=%u, keyval=%u, length=%d, string='%s', hardware_keycode=%u, group=%u\n", 
event->send_event, event->state, event->keyval, event->length, event->string, event->hardware_keycode, 
event->group);
  return FALSE;
}

int
main (int argc, char **argv)
{
  GtkWidget *win;

  gtk_init (&argc, &argv);

  win = gtk_message_dialog_new (NULL, 0, GTK_MESSAGE_QUESTION,
                                GTK_BUTTONS_OK_CANCEL, "OK?");
  g_signal_connect (win, "key-press-event", G_CALLBACK(on_key_press_event), 0);
  g_timeout_add (2500, on_timeout, win);
  gtk_dialog_run (GTK_DIALOG(win));

  return 0;
}

makefile

program: main.c
	clang -o "$@" $$(pkg-config --cflags --libs gtk+-3.0 gdk-3.0) "$<"