updating labels when a key is stroked

[Eric Wajnberg <eric wajnberg sophia inra fr>]

Hi there,

I need to develop a gtk code in which a label is changed each time a key 
is stroked on the keyboad. I thus use g_timeout_add() to launch on a 
regular basis a function that listens to key strokes. Within this 
function, I used a combination of kbhit()/getch() to collected the 
stroken keys (because I do not want the user to hit the <return> key all 
the time) and update the label accordingly. The following code is just a 
try, and seems ok:

#include <stdlib.h>
#include <stdio.h>
#include <conio.h>
#include <gtk/gtk.h>

int key=0;
char string[500];

int main(int argc, char **argv)
{
    /* declaration of widgets */
    GtkWidget *pWindow; /*main windows */
    GtkWidget *pLabel; /* a label */

    void OnDestroy(GtkWidget *pWidget, gpointer pData); /* function 
call back destroy */
    gboolean update(gpointer pData); /* function called at regular 
intervals */

    /* Initialisation of GTK+ */
    gtk_init(&argc, &argv);

    /* creation of the main window */
    pWindow = gtk_window_new(GTK_WINDOW_TOPLEVEL);

    /* parameters of the window */
    gtk_window_set_position(GTK_WINDOW(pWindow), GTK_WIN_POS_CENTER);
    gtk_window_set_default_size(GTK_WINDOW(pWindow), 300, 100);
    gtk_window_set_title(GTK_WINDOW(pWindow), "testing key input");

    /* creation of the label */
    (void)sprintf(string,"%d",key);
    pLabel=gtk_label_new(string);

    /* adding the label to the window */
    gtk_container_add(GTK_CONTAINER(pWindow), pLabel);

    /* signal connexion */
    g_signal_connect(G_OBJECT(pWindow), "destroy", 
G_CALLBACK(OnDestroy), NULL);

    /* function called at regular intervals .. */
    g_timeout_add((guint)1, update,(gpointer *)pLabel);

    /* showing the window */
    gtk_widget_show_all(pWindow);

    /* starting the loop */
    gtk_main();

    return EXIT_SUCCESS;
}

gboolean update(gpointer pData)
{
    /* updating the label */
    if (kbhit())
    {
        key=getch();
        (void)sprintf(string, "%d",key);
        gtk_label_set_label(GTK_LABEL(pData), string);
    }
    return TRUE;
}

void OnDestroy(GtkWidget *pWidget, gpointer pData)
{
    /* stopping the loop */
    gtk_main_quit();
}



The point is that this is actually not working correctly, because the 
keystrokes are collected on a console that is not there! In other words, 
the code above works well in "debug mode" (e.g., on Code::Blocks) when a 
debugging console is available, but not in "release mode" running 
without a console.

My question is thus: is there a way to listen to key stroked on the 
keyboard within a gtk application?

Thanks for any help on this!

Cheers, Eric.

--
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Eric Wajnberg
    Associated Professor at the
    University of Montreal (Quebec, Canada)
    I.N.R.A.
    400 Route des Chappes, BP 167,
    06903 Sophia Antipolis Cedex, France
    Tel: (33-0) 4.92.38.64.47
    Fax: (33-0) 4.92.38.65.57
    e-mail: wajnberg sophia inra fr
    Web page: http://www.sophia.inra.fr/perso/wajnberg/

    Editor-in-Chief of BioControl, Published by Springer.

    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~