gtk -examples

c/gtk-tutorial/helloworld/helloworld_with_box.c

@@ -1,36 +1,20 @@
 #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,
+/* Our new improved callback.  The data passed to this function
+ * is printed to stdout. */
+void callback( GtkWidget *widget,
                gpointer   data )
 {
-    g_print ("Hello World\n");
+    g_print ("Hello again - %s was pressed\n", (gchar *) data);
 }
 
+/* another callback */
 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 ();
+    return FALSE;
 }
 
 int main( int   argc,
@@ -39,59 +23,70 @@ int main( int   argc,
     /* GtkWidget is the storage type for widgets */
     GtkWidget *window;
     GtkWidget *button;
+    GtkWidget *box1;
 
     /* 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 */
+    /* 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. */
+    /* This is a new call, which just sets the title of our
+     * new window to "Hello Buttons!" */
+    gtk_window_set_title (GTK_WINDOW (window), "Hello Buttons!");
+
+    /* Here we just set a handler for delete_event that immediately
+     * exits GTK. */
     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 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");
+    /* We create a box to pack widgets into.  This is described in detail
+     * in the "packing" section. The box is not really visible, it
+     * is just used as a tool to arrange widgets. */
+    box1 = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 0);
 
-    /* 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. */
+    /* Put the box into the main window. */
+    gtk_container_add (GTK_CONTAINER (window), box1);
+
+    /* Creates a new button with the label "Button 1". */
+    button = gtk_button_new_with_label ("Button 1");
+    
+    /* Now when the button is clicked, we call the "callback" function
+     * with a pointer to "button 1" as its argument */
     g_signal_connect (G_OBJECT (button), "clicked",
-		      G_CALLBACK (hello), NULL);
+		      G_CALLBACK (callback), (gpointer) "button 1");
 
-    /* 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. */
-    g_signal_connect_swapped (G_OBJECT (button), "clicked",
-			      G_CALLBACK (gtk_widget_destroy),
-                              G_OBJECT (window));
+    /* Instead of gtk_container_add, we pack this button into the invisible
+     * box, which has been packed into the window. */
+    gtk_box_pack_start (GTK_BOX(box1), button, TRUE, TRUE, 0);
 
-    /* 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. */
+    /* Always remember this step, this tells GTK that our preparation for
+     * this button is complete, and it can now be displayed. */
     gtk_widget_show (button);
 
-    /* and the window */
+    /* Do these same steps again to create a second button */
+    button = gtk_button_new_with_label ("Button 2");
+
+    /* Call the same callback function with a different argument,
+     * passing a pointer to "button 2" instead. */
+    g_signal_connect (G_OBJECT (button), "clicked",
+		      G_CALLBACK (callback), (gpointer) "button 2");
+
+    gtk_box_pack_start(GTK_BOX (box1), button, TRUE, TRUE, 0);
+
+    /* The order in which we show the buttons is not really important, but I
+     * recommend showing the window last, so it all pops up at once. */
+    gtk_widget_show (button);
+
+    gtk_widget_show (box1);
+
     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). */
+    /* Rest in gtk_main and wait for the fun to begin! */
     gtk_main ();
 
     return 0;

c/gtk-tutorial/helloworld/run_helloworld_with_box.sh

@@ -0,0 +1,3 @@
+#!/bin/bash
+
+gcc -Wall -g helloworld_with_box.c -o helloworld_with_box `pkg-config --cflags gtk+-3.0` `pkg-config --libs gtk+-3.0` && ./helloworld_with_box