Toggle button as radio button solution

[Michal Tomcanyi <michal tomcanyi matfyz cz>]

Hello,

yesterday I've been searching archive for a code where toggle button
acts like a radio button. I found nothing out of use and the discussion
in mail list ended up - author used radio buttons instead. I am writing
chess client, and want to use toggle button as a chessboard square.
Selected square (movement start) will be pressed until another one
(movement destination) is pressed. Afterwards both buttons will raise.
This code should provide desired effect and I think it can be rewritten
for case "pressing one button will cause all other to raise".

If somebody has a better solution, please let me know. An inspiration
could be "tictactoe" example, where buttons are raised while callbacks
are disconnected by g_signal_handler_diconnect_by_func. I tried using
it, however some errors were returned in run-time so I gave up.
(Documentation says very little about it and I am not so skilled)
Maybe somebody find it useful.

Michal

------ Code start -----

#include <gtk/gtk.h>


void button_toggled(GtkToggleButton *bttn, gpointer data) {
        static GtkToggleButton *receiver=NULL;
        static GtkToggleButton *sender=NULL;
                
        g_print("Button %d toggled\n",GPOINTER_TO_INT(data));

        /* no button clicked before - user clicked for the first time */
        if (!receiver) { 
                receiver = bttn;
                return;
        }  
                
        /* one button has been toggled - user clicked on another one */
        if (receiver && receiver != bttn && 
            gtk_toggle_button_get_active(receiver)) {
                sender = bttn;
                gtk_toggle_button_set_active(receiver,FALSE);
                return;
        } 
                
        /* Serves for two possibilities:
         * 1, double click on the same button (push, raise) 
         * 2, another button ("sender") sent signal to "receiver" 
         *        which means, receiver should be raised  */
        if (receiver == bttn) {
                if (sender) gtk_toggle_button_set_active(sender,FALSE);
                receiver=NULL;
                return;
        }
                 
        /* "receiver" sends signal back to "sender", so that "sender" will
         *  raise again */
        if (sender == bttn) {
                sender = NULL;
                receiver = NULL;
                /* when the function exits, standard handler will raise 
                 * "sender" */
        }
        
}

int main(int argc, char *argv[]) {
        GtkWidget *win, *hbox, *bttn1, *bttn2;

        gtk_init(&argc, &argv);

        win = gtk_window_new(GTK_WINDOW_TOPLEVEL);
        gtk_widget_set_size_request(win,200,100);
        g_signal_connect(G_OBJECT(win),"destroy",G_CALLBACK(gtk_main_quit),
                NULL);
        bttn1=gtk_toggle_button_new_with_label("Button1");
        bttn2=gtk_toggle_button_new_with_label("Button2");
        g_signal_connect(G_OBJECT(bttn1),"toggled",G_CALLBACK(button_toggled),
                GINT_TO_POINTER(1));
        g_signal_connect(G_OBJECT(bttn2),"toggled",G_CALLBACK(button_toggled),
                GINT_TO_POINTER(2));

        hbox = gtk_hbox_new(TRUE,2);
        gtk_box_pack_start(GTK_BOX(hbox),bttn1,TRUE,TRUE,0);
        gtk_box_pack_start(GTK_BOX(hbox),bttn2,TRUE,TRUE,0);
        gtk_container_add(GTK_CONTAINER(win),hbox);
        gtk_widget_show_all(win);
        gtk_main();
        
        return(0);              
}

---------- Code end ----------