Sample Gtk application

main.c

/* Sample using gtk3 */
/* Compiling:  gcc `pkg-config --cflags gtk+-3.0` -o main main.c `pkg-config --libs gtk+-3.0`*/
#include <stdio.h>
#include <stdlib.h>
#include <gtk/gtk.h>

void on_window_destroy(GtkWidget *widget, gpointer data)
{
  gtk_main_quit();
}

void on_button_clicked(GtkWidget *widget, gpointer data)
{
  GtkWidget *entry = GTK_WIDGET(data);
  const gchar *input_text = gtk_entry_get_text(GTK_ENTRY(entry));
  
  GtkWidget *dialog = gtk_message_dialog_new(GTK_WINDOW(gtk_widget_get_toplevel(widget)), GTK_DIALOG_MODAL, GTK_MESSAGE_INFO, GTK_BUTTONS_OK, "We will store: %s", input_text);
  gtk_dialog_run(GTK_DIALOG(dialog));
  gtk_widget_destroy(dialog);
}

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

  gtk_init(&argc, &argv);

  GtkWidget *window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
  gtk_window_set_title(GTK_WINDOW(window), "Archibald");
  gtk_container_set_border_width(GTK_CONTAINER(window), 10);
  gtk_widget_set_size_request(window, 200, 100);
  g_signal_connect(window, "destroy", G_CALLBACK(on_window_destroy), NULL);
  GtkWidget *label = gtk_label_new("This is a test from a newbie");
  GtkWidget *input_text = gtk_entry_new();
  gtk_entry_set_placeholder_text(GTK_ENTRY(input_text), "Enter the value");
  GtkWidget *button = gtk_button_new_with_label("Save");
  g_signal_connect(button, "clicked", G_CALLBACK(on_button_clicked), input_text);
  GtkWidget *box = gtk_box_new(GTK_ORIENTATION_VERTICAL, 5);
  gtk_box_pack_start(GTK_BOX(box), label, FALSE, FALSE, 0);
  gtk_box_pack_start(GTK_BOX(box), input_text, FALSE, FALSE, 0);
  gtk_box_pack_start(GTK_BOX(box), button, FALSE, FALSE, 0);
  gtk_container_add(GTK_CONTAINER(window), box);
  gtk_widget_show_all(window);
  gtk_main();
  
  return EXIT_SUCCESS;
}

main2.c

/* Sample using gtk4 */
/* Compiling: gcc $(pkg-config --cflags gtk4) -o main main.c $(pkg-config --libs gtk4) */
#include <stdio.h>
#include <stdlib.h>
#include <gtk/gtk.h>

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

static void activate(GtkApplication *app, gpointer user_data)
{
  GtkWidget *window;
  GtkWidget *button;

  window = gtk_application_window_new(app);
  gtk_window_set_title(GTK_WINDOW (window), "Anibal");
  gtk_window_set_default_size(GTK_WINDOW (window), 200, 200);
  button = gtk_button_new_with_label("Check");
  g_signal_connect(button, "clicked", G_CALLBACK (print_hello), NULL);
  gtk_window_set_child(GTK_WINDOW (window), button);

  gtk_window_present(GTK_WINDOW(window));
}

int main(int argc, char **argv)
{
  GtkApplication *app;
  int status;
  /* To use the following enum, we must update glibc */
  /*app = gtk_application_new("io.digitalean.anibal", G_APPLICATION_DEFAULT_FLAGS);*/
  app = gtk_application_new("io.digitalean.anibal", 0);
  g_signal_connect(app, "activate", G_CALLBACK (activate), NULL);
  status = g_application_run(G_APPLICATION(app), argc, argv);
  g_object_unref(app);
  return status;
}