Passing Structure Of Widgets Problem

charIie · **Joined:** Tue Jan 08, 2008 7:39 pm **Posts:** 9

Hello,

I am having an issue with passing widgets to callback functions.

What I am trying to do is pass two widgets with one callback. One widget is a combo box and one is a status bar.

I prefer not to use global variables, so I figured my only way would be to create a structure and pass the structure.

I've tried this and it failed to work.

My structure look as such:

Code:

typedef struct status_and_widget {
   GtkWidget *widget;
   GtkWidget *status_bar;
} status_trans;

My declarations look like this in main:

Code:

GtkWidget *status_bar;
GtkWidget *combo_nearby_dev;

...

status_trans status_and_combo;
status_and_combo.widget = combo_nearby_dev;
status_and_combo.status_bar = status_bar;
g_signal_connect (G_OBJECT (button_nearby_dev), "clicked", G_CALLBACK (button_nearby_dev_callback), (gpointer)&status_and_combo);

...

And finally, my callback function:

Code:

static void button_nearby_dev_callback( GtkWidget *widget, gpointer data ) {
   status_trans *status_and_combo = (status_trans*)data;
   
   GList *list;
   bt_node *head;
   list = NULL;
   head = NULL;

   gtk_statusbar_push(GTK_STATUSBAR(status_and_combo->status_bar), 1, "Updating. Please Wait.");

    /* Fills Combo Box */
   bt_populate_list(&head);
   list = g_list_append (list, "John");

   /* Adds list to combo box */
   gtk_combo_set_popdown_strings(GTK_COMBO(status_and_combo->widget), list);    
   
   gtk_statusbar_pop(GTK_STATUSBAR(status_and_combo->status_bar), 1);
}

It does update the combo box, but does not do anything for the status_bar.

Also, the bt_populate_list() function searches for local bluetooth devices which takes some time. So I don't believe that I'm not seeing it due to it being too quick but I'm not positive.

Any help would be appreciated.

Thanks
Brian

rdo · **Posted:** Tue Jan 08, 2008 9:24 pm

Right after your gtk_statusbar_push() you can run

gtk_main_iteration();

to iterate through the main loop one time and process the push message.

The event is not being fired until after your event ends (I think).

Micah Carrick · **Posted:** Wed Jan 09, 2008 12:08 am

as mentioned...

while (gtk_events_pending()) gtk_main_iteration();

will update the GUI with pending events before proceeding which would insure that the status bar message is shown before moving on.

Sometimes stepping through the code can help with this type of issue. Compile with the -g flag and then using gdb, you can simply do:

gdb myprogram

which will load your program into gdb. Then enter: "b button_nearby_dev_callback" to put a breakpoint in the callback and then type "r" to run the app. When you click the button, it will pause at the beginning of your callback function. Press "n" to step through each call. I'll bet that after the gtk_statusbar_push() call the GUI still won't reflect this change. Keep typing "n" to keep stepping to the next line of code.

charIie · **Joined:** Tue Jan 08, 2008 7:39 pm **Posts:** 9

Would I need to update after the pop as well? It works without it, but I was wondering why.

The only thing I could think of is that since it is going back to main it would update it.

Thanks for all of the help.

Brian

rdo · **Posted:** Wed Jan 09, 2008 3:17 pm

You shouldn't have to call it again after the pop; the bt_list process is blocking the events from being fired, therefore, you are getting a push() and pop() event after your callback completes. So after your event finishes the pop message is fired successfully.

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Passing Structure Of Widgets Problem

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