The MagPi - February 2020

(You can select one of two different formats on the

save window – use the default GtkBuilder option.)

Make sure you save the file in the same directory

where you are storing your GTK source code.

Using a layout file in a GTK application

Now we need to load the layout file into some GTK

code. Try the following:

#include <gtk/gtk.h>

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

{

gtk_init (&argc, &argv);

GtkBuilder *builder = gtk_builder_new ();

gtk_builder_add_from_file (builder,

"mylayout.glade", NULL);

GtkWidget *win = (

GtkWidget *) gtk_builder_get_object (

builder, "window1");

gtk_widget_show_all (win);

gtk_main ();

}

The gtk_init and gtk_main calls are the same as

we have seen before, but the code between them

uses a GtkBuilder, a code object which reads in and

processes a layout file.

We create a GtkBuilder object:

GtkBuilder *builder = gtk_builder_new ();

We then read the layout file into the builder.

gtk_builder_add_from_file (builder,

"mylayout.glade", NULL);

The widgets we created in the layout file can now

all be accessed by calls to gtk_builder_get_object,

and used as before. So we get the object which was

named window1 in the layout file.

GtkWidget *win = (

GtkWidget *) gtk_builder_get_object (

builder, "window1");

And we show it as before:

gtk_widget_show_all (win);

If you build and run this code, our simple window

should be displayed on the screen (Figure 6).

To make the widgets actually do things, we need

to connect signals as before, so let’s modify our

code accordingly.

Figure 3 Adding

a vertical box

To make the widgets

actually do things, we need

to connect signals

Figure 3

TUTORIAL

56 magpi.cc Glade layout editor with C and GTK