All Boards GTK Manually

Document created by jesseg Employee on Aug 15, 2012Last modified by grantw on Mar 8, 2013
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You can create GTK applications manually—this is just like creating Graphics Java Applications. It uses a similar layout idea!

Copy this example and save as helloworld.c:

/* example-start helloworld helloworld.c */

#include <gtk/gtk.h>

/* This is a callback function. The data arguments are ignored
* in this example. More on callbacks below. */
void hello( GtkWidget *widget, gpointer   data )
{
   g_print ("Hello World\n");
}

gint delete_event( GtkWidget *widget, GdkEvent  *event,  gpointer   data )
{
   /* If you 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 */
void destroy( GtkWidget *widget, gpointer   data )
{
   gtk_main_quit();
}

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, usually by the "close" option, 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. */
   gtk_signal_connect (GTK_OBJECT (window), "delete_event",
                       GTK_SIGNAL_FUNC (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. */
   gtk_signal_connect (GTK_OBJECT (window), "destroy",
                       GTK_SIGNAL_FUNC (destroy), NULL);
   
   /* Sets the border width 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 as its argument.  The hello()
    * function is defined above. */
   gtk_signal_connect (GTK_OBJECT (button), "clicked",
                       GTK_SIGNAL_FUNC (hello), NULL);
   
   /* This will cause the window to be destroyed by calling
    * gtk_widget_destroy(window) when "clicked".  Again, the destroy
    * signal could come from here, or the window manager. */
   gtk_signal_connect_object (GTK_OBJECT (button), "clicked",
                              GTK_SIGNAL_FUNC (gtk_widget_destroy),
                              GTK_OBJECT (window));
   
   /* This packs the button into the window (a gtk container). */
   gtk_container_add (GTK_CONTAINER (window), button);
   
   /* The 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);
}
/* example-end */


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