11.7. Paned Window Widgets

The paned window widgets are useful when you want to divide an area into two parts, with the relative size of the two parts controlled by the user. A groove is drawn between the two portions with a handle that the user can drag to change the ratio. The division can either be horizontal (HPaned) or vertical (VPaned).

To create a new paned window, call one of:

GtkWidget *gtk_hpaned_new (void);

GtkWidget *gtk_vpaned_new (void);

After creating the paned window widget, you need to add child widgets to its two halves. To do this, use the functions:

void gtk_paned_add1 (GtkPaned *paned, GtkWidget *child);

void gtk_paned_add2 (GtkPaned *paned, GtkWidget *child);

gtk_paned_add1() adds the child widget to the left or top half of the paned window. gtk_paned_add2() adds the child widget to the right or bottom half of the paned window.

As an example, we will create part of the user interface of an imaginary email program. A window is divided into two portions vertically, with the top portion being a list of email messages and the bottom portion the text of the email message. Most of the program is pretty straightforward. A couple of points to note: text can't be added to a Text widget until it is realized. This could be done by calling gtk_widget_realize(), but as a demonstration of an alternate technique, we connect a handler to the "realize" signal to add the text. Also, we need to add the GTK_SHRINK option to some of the items in the table containing the text window and its scrollbars, so that when the bottom portion is made smaller, the correct portions shrink instead of being pushed off the bottom of the window.

#include <stdio.h>
#include <gtk/gtk.h>
   
/* Create the list of "messages" */
static GtkWidget *create_list( void )
{

    GtkWidget *scrolled_window;
    GtkWidget *tree_view;
    GtkListStore *model;
    GtkTreeIter iter;
    GtkCellRenderer *cell;
    GtkTreeViewColumn *column;

    int i;
   
    /* Create a new scrolled window, with scrollbars only if needed */
    scrolled_window = gtk_scrolled_window_new (NULL, NULL);
    gtk_scrolled_window_set_policy (GTK_SCROLLED_WINDOW (scrolled_window),
				    GTK_POLICY_AUTOMATIC, 
				    GTK_POLICY_AUTOMATIC);
   
    model = gtk_list_store_new (1, G_TYPE_STRING);
    tree_view = gtk_tree_view_new ();
    gtk_scrolled_window_add_with_viewport (GTK_SCROLLED_WINDOW (scrolled_window), 
                                           tree_view);
    gtk_tree_view_set_model (GTK_TREE_VIEW (tree_view), GTK_TREE_MODEL (model));
    gtk_widget_show (tree_view);
   
    /* Add some messages to the window */
    for (i = 0; i < 10; i++) {
        gchar *msg = g_strdup_printf ("Message #%d", i);
        gtk_list_store_append (GTK_LIST_STORE (model), &iter);
        gtk_list_store_set (GTK_LIST_STORE (model), 
	                    &iter,
                            0, msg,
	                    -1);
	g_free (msg);
    }
   
    cell = gtk_cell_renderer_text_new ();

    column = gtk_tree_view_column_new_with_attributes ("Messages",
                                                       cell,
                                                       "text", 0,
                                                       NULL);
  
    gtk_tree_view_append_column (GTK_TREE_VIEW (tree_view),
	  		         GTK_TREE_VIEW_COLUMN (column));

    return scrolled_window;
}
   
/* Add some text to our text widget - this is a callback that is invoked
when our window is realized. We could also force our window to be
realized with gtk_widget_realize, but it would have to be part of
a hierarchy first */

static void insert_text( GtkTextBuffer *buffer )
{
   GtkTextIter iter;
 
   gtk_text_buffer_get_iter_at_offset (buffer, &iter, 0);

   gtk_text_buffer_insert (buffer, &iter,   
    "From: [email protected]\n"
    "To: [email protected]\n"
    "Subject: Made it!\n"
    "\n"
    "We just got in this morning. The weather has been\n"
    "great - clear but cold, and there are lots of fun sights.\n"
    "Sojourner says hi. See you soon.\n"
    " -Path\n", -1);
}
   
/* Create a scrolled text area that displays a "message" */
static GtkWidget *create_text( void )
{
   GtkWidget *scrolled_window;
   GtkWidget *view;
   GtkTextBuffer *buffer;

   view = gtk_text_view_new ();
   buffer = gtk_text_view_get_buffer (GTK_TEXT_VIEW (view));

   scrolled_window = gtk_scrolled_window_new (NULL, NULL);
   gtk_scrolled_window_set_policy (GTK_SCROLLED_WINDOW (scrolled_window),
		   	           GTK_POLICY_AUTOMATIC,
				   GTK_POLICY_AUTOMATIC);

   gtk_container_add (GTK_CONTAINER (scrolled_window), view);
   insert_text (buffer);

   gtk_widget_show_all (scrolled_window);

   return scrolled_window;
}
   
int main( int   argc,
          char *argv[] )
{
    GtkWidget *window;
    GtkWidget *vpaned;
    GtkWidget *list;
    GtkWidget *text;

    gtk_init (&argc, &argv);
   
    window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
    gtk_window_set_title (GTK_WINDOW (window), "Paned Windows");
    g_signal_connect (G_OBJECT (window), "destroy",
	              G_CALLBACK (gtk_main_quit), NULL);
    gtk_container_set_border_width (GTK_CONTAINER (window), 10);
    gtk_widget_set_size_request (GTK_WIDGET (window), 450, 400);

    /* create a vpaned widget and add it to our toplevel window */
   
    vpaned = gtk_vpaned_new ();
    gtk_container_add (GTK_CONTAINER (window), vpaned);
    gtk_widget_show (vpaned);
   
    /* Now create the contents of the two halves of the window */
   
    list = create_list ();
    gtk_paned_add1 (GTK_PANED (vpaned), list);
    gtk_widget_show (list);
   
    text = create_text ();
    gtk_paned_add2 (GTK_PANED (vpaned), text);
    gtk_widget_show (text);
    gtk_widget_show (window);

    gtk_main ();

    return 0;
}