undefined reference to...

Question

Hi

I have the following C GTK+ code and I get the following error trying to compile:

undefined reference to gdk_pixbuf_new_from_file_utf8

Code:

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

GdkPixbuf *create_pixbuf(const gchar *filename)
{
    GdkPixbuf *pixbuf;
    GError *error = NULL;
    pixbuf = gdk_pixbuf_new_from_file(filename, &error);
    if (!pixbuf)
    {
        fprintf(stderr, "%s\n", error->message);
        g_error_free(error);
    }

    return pixbuf;
}

int main (int argc, char *argv[])
{

    GtkWidget *window;

    gtk_init(&argc, &argv);

    window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
    gtk_window_set_title(GTK_WINDOW(window), "Center");
    gtk_window_set_default_size(GTK_WINDOW(window), 230, 150);
    gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);
    gtk_window_set_icon(GTK_WINDOW(window), create_pixbuf("someimg.jpg"));
    gtk_widget_show(window);

    g_signal_connect_swapped(G_OBJECT(window), "destroy",
        G_CALLBACK(gtk_main_quit), NULL);

    gtk_main();

  return 0;
}

Can anybody tell me whats wrong?

Answer 1

gdk_pixbuf_new_from_file is defined in gtk-2.0/gdk-pixbuf/gdk-pixbuf-core.h

But rather than including that file directly, it looks like the gdk-pixbuf library expects you to use just one header for all functionality. Try adding the following line:

#include <gdk-pixbuf/gdk-pixbuf.h>

(gdk_pixbuf_new_from_file is a preprocessor macro which simply functions as an alias for gdk_pixbuf_new_from_file_utf8. This is why the error message shows a different function name than what you actually used in your code example.)

Answer 2

Never used GTK, but 2 seconds googling suggests you need to add:

#include <gdk-pixbuf/gdk-pixbuf.h>

To the top of your file.

Answer 3

Just successfully compiled your code after doing the following:

Add the following two includes:

#include <glib/gerror.h>
#include <gdk-pixbuf/gdk-pixbuf.h>

And compile with:

gcc `pkg-config --cflags --libs gtk+-2.0` test.c -o test

The pkg-config gives the following output:

-I/usr/include/gtk-2.0 -I/usr/lib/gtk-2.0/include -I/usr/include/atk-1.0 -I/usr/include/cairo -I/usr/include/pango-1.0 -I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include -I/usr/include/pixman-1 -I/usr/include/freetype2 -I/usr/include/libpng12  -lgtk-x11-2.0 -lgdk-x11-2.0 -latk-1.0 -lgio-2.0 -lpangoft2-1.0 -lgdk_pixbuf-2.0 -lpangocairo-1.0 -lcairo -lpango-1.0 -lfreetype -lfontconfig -lgobject-2.0 -lgmodule-2.0 -lglib-2.0

So you need to link with the following libraries:

• gtk-x11-2.0
• gdk-x11-2.0
• atk-1.0
• gio-2.0
• pangoft2-1.0
• gdk_pixbuf-2.0
• pangocairo-1.0
• cairo
• pango-1.0
• freetype
• fontconfig
• gobject-2.0
• gmodule-2.0
• glib-2.0

You may be able to leave out a few, if you want to try just start with gdk_pixbuf-2.0 and see if you still get any undefined references when you link.

Just tried, seems that for your code gtk-x11-2.0 and gdk_pixbuf-2.0 are sufficient.

A quick google seems to indicate that in your project options window you should have a linker tab where you can list all the libraries that should be linked with your code. If you're not on linux/unix you may need a diferent gtk library since gtk-x11-2.0 is specific to the X Window System.