GTK Notbook Change Pages

VarwigSoftware · **Joined:** Sat Mar 03, 2012 2:45 am **Posts:** 18

Hello All,

I am trying to write a function to change tabs on a click of a button. My Code is Below. It errors out saying "Gtk-CRITICAL **: gtk_notebook_set_current_page: assertion `GTK_IS_NOTEBOOK (notebook)' failed" I am showing the widget. I know that is in the gnome help.

Any Ideas?

Code:

void btn_login_clicked_cb (GtkButton *btn_login, GtkNotebook *notebook, gpointer user_data)
{
   GtkWidget *login = GTK_WIDGET(btn_login);
   gtk_button_set_label (login, "Please Wait..."); // THIS WORKS :)

   GtkWidget *nb = GTK_WIDGET(notebook);
   gtk_widget_show_all(nb);
   gtk_notebook_set_current_page (nb, 1); // THIS DOES NOT
}

Thank You

tadeboro · **Posted:** Fri Sep 21, 2012 10:37 pm

Hi.

You haven't read the docs about signal connections properly. Prototype of each signal handler is documented in API docs. Signal for GtkButton::clicked (I guess that is the signal you're connecting to) is

Code:

void callback (GtkButton *button, gpointer data)

Your callback has 3 arguments, which means that your local variables most probably contain garbage. Read docs about signal connection and then search this forum for methods of passing data around the various parts of your app and you should be able to fix this.

Cheers,
Tadej

VarwigSoftware · **Joined:** Sat Mar 03, 2012 2:45 am **Posts:** 18

I have looked at the Signal Connection and having multiple arguments in GTK while on google and gtkforurms.com - I have found http://stackoverflow.com/questions/6684466/c-passing-multiple-arguments-to-a-callback-function-in-gtk and http://ubuntuforums.org/showthread.php?t=701485 but still not working. I created a struct with GtkWidget *btn_login, GtkWidget *notebook, and still has an error. I can't see what I am doing wrong in it.

Code:

struct widgets_login
{
    GtkWidget *btn_login;
    GtkWidget *notebook;
};


void btn_login_clicked_cb (GtkWidget *btn_login, gpointer data)
{
   struct widgets_login * w ;
   w = ( struct widgets_login *) data ;

   GtkWidget *login = GTK_WIDGET(btn_login);
   gtk_widget_set_sensitive (login, FALSE);
   gtk_button_set_label (login, "Please Wait...");
   
   gtk_notebook_set_current_page(GTK_NOTEBOOK(w->notebook), 1);
}

Paul Childs · **Posted:** Sat Sep 22, 2012 1:27 pm

Why are you putting the button in a structure. It is already passed as being the one that the signal activates on. In this case you only need to pass the notebook and so don't need a structure; thus can pass it in the gpointer as is. E.g.:

Code:

void btn_login_clicked_cb (GtkButton *btn_login, gpointer data)
{
   gtk_widget_set_sensitive (GTK_WIDGET(btn_login), FALSE);
   gtk_button_set_label (login, "Please Wait...");
   gtk_notebook_set_current_page(GTK_NOTEBOOK(data), 1);
}

int main(int argc, char *argv[])
{
   ...
   g_signal_connect(G_OBJECT(btn_login), "clicked", G_CALLBACK(btn_login_clicked_cb), (gpointer) notebook);
   ...

The other thing is: Yes you are allowed to declare a global variable. And for something like a notebook that is routinely altered by various functions, it makes sense to do so. Structured programming may say otherwise but to that I say goto

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