GTK4 Building user interfaces

builder.ui

<?xml version="1.0" encoding="UTF-8"?>
<interface>
  <object id="window" class="GtkWindow">
    <property name="title">Grid</property>
    <child>
      <object id="grid" class="GtkGrid">
        <child>
          <object id="button1" class="GtkButton">
            <property name="label">Button 1</property>
            <layout>
              <property name="column">0</property>
              <property name="row">0</property>
            </layout>
          </object>
        </child>
        <child>
          <object id="button2" class="GtkButton">
            <property name="label">Button 2</property>
            <layout>
              <property name="column">1</property>
              <property name="row">0</property>
            </layout>
          </object>
        </child>
        <child>
          <object id="quit" class="GtkButton">
            <property name="label">Quit</property>
            <layout>
              <property name="column">0</property>
              <property name="row">1</property>
              <property name="column-span">2</property>
            </layout>
          </object>
        </child>
      </object>
    </child>
  </object>
</interface>

main.c

#include <gtk/gtk.h>
#include <glib/gstdio.h>


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


static void
quit_cb (GtkWindow *window)
{
  gtk_window_close (window);
}


static void
activate (GtkApplication *app,
          gpointer        user_data)
{
  /* Construct a GtkBuilder instance and load our UI description. */
  GtkBuilder *builder = gtk_builder_new ();
  gtk_builder_add_from_file (builder, "builder.ui", NULL);

  /* Connect signal handlers to the constructed widgets. */
  GObject *window = gtk_builder_get_object (builder, "window");
  gtk_window_set_application (GTK_WINDOW (window), app);

  GObject *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_swapped (button, "clicked", G_CALLBACK (quit_cb), window);

  gtk_widget_show (GTK_WIDGET (window));

  /* We do not need the builder any more. */
  g_object_unref (builder);
}


int
main (int argc, char *argv[])
{
#ifdef GTK_SRCDIR
  g_chdir (GTK_SRCDIR);
#endif

  GtkApplication *app = gtk_application_new ("org.gtk.example", G_APPLICATION_FLAGS_NONE);
  g_signal_connect (app, "activate", G_CALLBACK (activate), NULL);

  int status = g_application_run (G_APPLICATION (app), argc, argv);
  g_object_unref (app);

  return status;
}

Makefile

CFLAGS = -Wall -g `pkg-config --cflags gtk4`
LDFLAGS = `pkg-config --libs gtk4`

all: main.c
	$(CC) -o main main.c $(CFLAGS) $(LDFLAGS)

clean:
	rm -f *~
	rm -f *.o
	rm -f main