Problems with gtk_text_view_get_buffer ()

greg1313 · **Joined:** Fri Aug 28, 2009 12:57 am **Posts:** 2

Hi,

I'm writing a small app to display the contents of text files and I have the following code:

Code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <gtk/gtk.h>

void 
on_window_destroy (GtkObject *object, gpointer user_data)
{
        gtk_main_quit();
}

int
main (int argc, char *argv[])
{
        GtkBuilder              *builder;
        GtkWidget               *window;
   GtkWidget      *textview;
   GtkTextBuffer      *textbuffer;

        gtk_init (&argc, &argv);
        
        builder = gtk_builder_new ();
        gtk_builder_add_from_file (builder, "fv.xml", NULL);

        window = GTK_WIDGET (gtk_builder_get_object (builder, "window"));
        gtk_builder_connect_signals (builder, NULL);          
        g_object_unref (G_OBJECT (builder));

   textview = gtk_text_view_new ();

line 32: textbuffer = gtk_text_view_get_buffer (textview);

   gtk_widget_show (window);       
        gtk_main ();
        
        return 0;
}

and the following is the output from the compiler, gcc version 4.3.2 (Debian 4.3.2-1.1):

Code:

greg@debian:/fv$ gtk-builder-convert fv.glade fv.xml
Wrote fv.xml
greg@debian:/fv$ gcc -Wall -g -o fv fv.c -export-dynamic `pkg-config --cflags --libs gtk+-2.0`
fv.c: In function ‘main’:
fv.c:32: warning: passing argument 1 of ‘gtk_text_view_get_buffer’ from incompatible pointer type

I've tried passing textview, *textview and &textview, but I still get this warning and it seems to be tied into problems I'm having expanding my code. Is there any way to get rid of this warning? Am I using the correct syntax in the code I have posted?

Thanks.

errol · **Posted:** Mon Jan 09, 2012 7:40 am

Hi,

The C pointer you are trying to pass is of the incorrect type and you will need to cast it to the right type to get rid of the warning.

Change the line

Code:

textbuffer = gtk_text_view_get_buffer (textview);

to

Code:

textbuffer = gtk_text_view_get_buffer (GTK_TEXT_VIEW(textview));

The macro GTK_TEXT_VIEW() will do the casting for you and check that it really points to a GtkTextView and not some other type of widget.

Note most calls to create a widget will return GtkWidget as this is the base of all widgets and you will in most cases need to do some casting using the GTK macros to get to your actual widget.

Edited for my silly mistakes!

abhijangda · **Joined:** Sun Apr 03, 2011 11:12 am **Posts:** 63

Hey, I think it should be GTK_TEXT_VIEW() not GTK_TEXTVIEW (as far as, I know. In gtk+2 I have used GTK_TEXT_VIEW only haven't tried GTK_TEXTVIEW()).

errol · **Posted:** Mon Jan 09, 2012 8:22 pm

Yes the macro should be GTK_TEXT_VIEW() my mistake. It was one of the last things I did before rushing off to work.

greg1313 · **Joined:** Fri Aug 28, 2009 12:57 am **Posts:** 2

Thanks! So far so good.

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