GTK hello world in C (Not with Glade)

#include <gtk/gtk.h>

/*
* This is a callback function. The data arguments are ignored
* in this example. More on callbacks below
*/

static void hello(GtkWidget *widget, gpointer data){
g_print(“Hello World\n”);
};

static gboolean delete_event(GtkWidget *widget, GdkEvent *event, gpointer data){
/* If your return FALSE in the “delete_event” signal handler,
* GTK will emit the “destroy” signal. Returning TRUE means
* you don’t want the window to be destroyed.
* This is useful for popping up ‘are you sure you want to quit?’
* type dialogs.
*/

g_print(“delete event occurred\n”);

/* Change TRUE to FALSE and the main window will be destroyed with
* a “delete_event”.
*/

return TRUE;
};

/* Another callback */
static void destroy(GtkWidget *widget, gpointer data){
gtk_main_quit();
};

/* And now the main 😀 */
int main(int argc, char *argv[]){
/* GTkWidget is the storage type for widgets */
GtkWidget *window;
GtkWidget *button;

/* This is called in all GTK applications. Arguments are parsed
* from the command line and are returned to the application.
*/
gtk_init(&argc, &argv);

/* create a new window */
window = gtk_window_new(GTK_WINDOW_TOPLEVEL);

/* When the window is given the “delete_event” signal (this is given
* by the window manager, usally by the “close” opion, or on the
* titlebar), we ask it to call the delete_event() function
* as defined above. The data passed to the callback
* function is NULL and is ignored in the callback function.
*/
g_signal_connect(G_OBJECT(window), “delete_event”, G_CALLBACK(delete_event), NULL);

/* Here we connect the “destroy” event to a signal handler.
* This event occurs when we call gtk_widget_destroy() on the window,
* or if we return FALSE in the “delete_event” callback.
*/
g_signal_connect(G_OBJECT(window), “destroy”, G_CALLBACK(destroy), NULL);

/* Sets the border with of the window. */
gtk_container_set_border_width(GTK_CONTAINER(window), 10);

/* Creates a new button with the label “Hello World”. */
button = gtk_button_new_with_label(“Hello World”);

/* When the button receives the “clicked” signal, it will call the
* function hello() passing it NULL ad its argument. The hello()
* function is defined above. */
g_signal_connect(G_OBJECT(button), “clicked”, G_CALLBACK(hello), NULL);

/* This will cause the window th be destroyed by calling
* gtk_widget_destroy(window) when “clicked”. Agin the destroy
* signal could come from here, or the window manager. */
g_signal_connect_swapped(G_OBJECT(button), “clicked”, G_CALLBACK(gtk_widget_destroy), G_OBJECT(window));

/* This packs the button into the window(a gtk container). */
gtk_container_add(GTK_CONTAINER(window), button);

/* This final step is to display this newly created widget. */
gtk_widget_show(button);

/* and the window */
gtk_widget_show(window);

/* All GTK applications must have a gtk_main(). Control ends here
* and waits for an event to occur (like a key press or
* mouse event).
*/
gtk_main();

return 0;
};

/*
* Compile: gcc helloworld.c -o helloworld `pkg-config –cflags –libs gtk+-2.0`
*/

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