Building user interfaces

Create a new file with the following content named example-3.c.

#include <gtk/gtk.h>

static void
print_hello (GtkWidget *widget,
             gpointer   data)
{
  g_print ("Hello World\n");
}

int
main (int   argc,
      char *argv[])
{
  GtkBuilder *builder;
  GObject *window;
  GObject *button;
  GError *error = NULL;

  gtk_init (&argc, &argv);

  /* Construct a GtkBuilder instance and load our UI description */
  builder = gtk_builder_new ();
  if (gtk_builder_add_from_file (builder, "builder.ui", &error) == 0)
    {
      g_printerr ("Error loading file: %s\n", error->message);
      g_clear_error (&error);
      return 1;
    }

  /* Connect signal handlers to the constructed widgets. */
  window = gtk_builder_get_object (builder, "window");
  g_signal_connect (window, "destroy", G_CALLBACK (gtk_main_quit), NULL);

  button = gtk_builder_get_object (builder, "button1");
  g_signal_connect (button, "clicked", G_CALLBACK (print_hello), NULL);

  button = gtk_builder_get_object (builder, "button2");
  g_signal_connect (button, "clicked", G_CALLBACK (print_hello), NULL);

  button = gtk_builder_get_object (builder, "quit");
  g_signal_connect (button, "clicked", G_CALLBACK (gtk_main_quit), NULL);

  gtk_main ();

  return 0;
}

Create a new file with the following content named builder.ui.

<interface>
  <object id="window" class="GtkWindow">
    <property name="visible">True</property>
    <property name="title">Grid</property>
    <property name="border-width">10</property>
    <child>
      <object id="grid" class="GtkGrid">
        <property name="visible">True</property>
        <child>
          <object id="button1" class="GtkButton">
            <property name="visible">True</property>
            <property name="label">Button 1</property>
          </object>
          <packing>
            <property name="left-attach">0</property>
            <property name="top-attach">0</property>
          </packing>
        </child>
        <child>
          <object id="button2" class="GtkButton">
            <property name="visible">True</property>
            <property name="label">Button 2</property>
          </object>
          <packing>
            <property name="left-attach">1</property>
            <property name="top-attach">0</property>
          </packing>
        </child>
        <child>
          <object id="quit" class="GtkButton">
            <property name="visible">True</property>
            <property name="label">Quit</property>
          </object>
          <packing>
            <property name="left-attach">0</property>
            <property name="top-attach">1</property>
            <property name="width">2</property>
          </packing>
        </child>
      </object>
      <packing>
      </packing>
    </child>
  </object>
</interface>