CODEWITHSUNDEEP
cgtk3glade
Nico Angelo Dela Cruz
Nico Angelo Dela Cruz

Reputation: 1

How do I Check for the Key Pressed in GTK3 (C)?

We're trying to filter keys in the key press event in C using glade. But we can't figure out how to filter those keys. Here is the code:

 // called when key pressed
void on_window_main_key_press_event()
{

}

Upvotes: 0

Views: 2069

Answers (3)

Waqar
Waqar

Reputation: 9331

You have to use GdkEventKey to handle key press events.

The struct looks like this:

struct GdkEventKey {
  GdkEventType type;  // is it a key-press or key release event
  GdkWindow *window; // the window receiving the event
  gint8 send_event;  // whether the event was sent explicitly. It's TRUE in that case
  guint32 time;    //time of event in ms
  guint state;     //a bit mask representing state of (Ctrl/Alt/Shift)
  guint keyval;   // the key that was pressed
  gint length;    // length of string
  gchar *string;   //the string that may result from this kepress
  guint16 hardware_keycode; //hardware key code
  guint8 group; // keyboard group
  guint is_modifier : 1;  //whether the key is mapped as modifier
};

You can find the values of all key presses in this file: gdkkeysyms.h

Here's a simple example:

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

gboolean
on_window_main_key_press_event (GtkWidget *widget, GdkEventKey *event, gpointer user_data);

int main (int argc, char *argv[])
{
  GtkWidget *window;

  gtk_init (&argc, &argv);

  window = gtk_window_new (GTK_WINDOW_TOPLEVEL);

  g_signal_connect (G_OBJECT (window), "key_press_event", G_CALLBACK (on_window_main_key_press_event), NULL);

  gtk_widget_show_all (window);

  gtk_main ();

  return 0;
}

gboolean
on_key_press (GtkWidget *widget, GdkEventKey *event, gpointer user_data)
{
  switch (event->keyval)
  {
    case GDK_Z:
    case GDK_z:
      printf("key pressed: %s\n", "Z");
      break;
    case GDK_S
    case GDK_s:
      if (event->state & GDK_SHIFT_MASK)
      {
        printf("key pressed: %s\n", "shift + s");
      }
      else if (event->state & GDK_CONTROL_MASK)
      {
        printf("key pressed: %s\n", "ctrl + s");
      }
      else
      {
        printf("key pressed: %s\n", "s");
      }
      break;
    default:
      return FALSE; 
  }
  return FALSE; 
}

Upvotes: 2

user12211554
user12211554

Reputation:

I think this should help you

void on_window_main_key_press_event(GtkWidget *widget, GdkEventKey *key, gpointer user_data) {
    int TheKeyThatWasPressed = key->keyval; //Incase you need to find out what key got pressed
}

Then use this in your main function:

g_signal_connect(Window, "key-press-event", G_CALLBACK(KeyPressHandler), NULL);

Upvotes: 0

Siva Guru
Siva Guru

Reputation: 694

the callback function for keypress is

on_key_press(GtkWidget *widget, GdkEventKey *key, gpointer user_data)

GdkEventKey structure is defined here (https://developer.gnome.org/gdk3/stable/gdk3-Event-Structures.html#GdkEventKey) and keyval returns the value of the key pressed you can compare it like this.

strcmp(gdk_keyval_name(key->keyval), "Return") == 0

Upvotes: 2

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