GTK+ 1.2 Tutorial
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# 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.

A paned widget can be changed visually using the following two functions.

    void gtk_paned_set_handle_size( GtkPaned *paned,
                                    guint16   size);

    void gtk_paned_set_gutter_size( GtkPaned *paned,
                                    guint16   size);

The first of these sets the size of the handle and the second sets the size of the gutter that is between the two parts 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.

    /* example-start paned paned.c */

    #include <stdio.h>
    #include <gtk/gtk.h>

    /* Create the list of "messages" */
    GtkWidget *create_list( void )
    {

        GtkWidget *scrolled_window;
        GtkWidget *list;
        GtkWidget *list_item;

        int i;
        char buffer[16];

        /* 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);

        /* Create a new list and put it in the scrolled window */
        list = gtk_list_new ();
        gtk_scrolled_window_add_with_viewport (
                   GTK_SCROLLED_WINDOW (scrolled_window), list);
        gtk_widget_show (list);

        /* Add some messages to the window */
        for (i=0; i<10; i++) {

        	sprintf(buffer,"Message #%d",i);
        	list_item = gtk_list_item_new_with_label (buffer);
        	gtk_container_add (GTK_CONTAINER(list), list_item);
        	gtk_widget_show (list_item);

        }

        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 */

    void realize_text( GtkWidget *text,
                       gpointer data )
    {
        gtk_text_freeze (GTK_TEXT (text));
        gtk_text_insert (GTK_TEXT (text), NULL, &text->style->black, NULL,
        "From: pathfinder@nasa.gov\n"
        "To: mom@nasa.gov\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);

        gtk_text_thaw (GTK_TEXT (text));
    }

    /* Create a scrolled text area that displays a "message" */
    GtkWidget *create_text( void )
    {
        GtkWidget *table;
        GtkWidget *text;
        GtkWidget *hscrollbar;
        GtkWidget *vscrollbar;

        /* Create a table to hold the text widget and scrollbars */
        table = gtk_table_new (2, 2, FALSE);

        /* Put a text widget in the upper left hand corner. Note the use of
         * GTK_SHRINK in the y direction */
        text = gtk_text_new (NULL, NULL);
        gtk_table_attach (GTK_TABLE (table), text, 0, 1, 0, 1,
    		      GTK_FILL | GTK_EXPAND,
    		      GTK_FILL | GTK_EXPAND | GTK_SHRINK, 0, 0);
        gtk_widget_show (text);

        /* Put a HScrollbar in the lower left hand corner */
        hscrollbar = gtk_hscrollbar_new (GTK_TEXT (text)->hadj);
        gtk_table_attach (GTK_TABLE (table), hscrollbar, 0, 1, 1, 2,
    		      GTK_EXPAND | GTK_FILL, GTK_FILL, 0, 0);
        gtk_widget_show (hscrollbar);

        /* And a VScrollbar in the upper right */
        vscrollbar = gtk_vscrollbar_new (GTK_TEXT (text)->vadj);
        gtk_table_attach (GTK_TABLE (table), vscrollbar, 1, 2, 0, 1,
    		      GTK_FILL, GTK_EXPAND | GTK_FILL | GTK_SHRINK, 0, 0);
        gtk_widget_show (vscrollbar);

        /* Add a handler to put a message in the text widget when it is realized */
        gtk_signal_connect (GTK_OBJECT (text), "realize",
    			GTK_SIGNAL_FUNC (realize_text), NULL);

        return table;
    }

    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");
        gtk_signal_connect (GTK_OBJECT (window), "destroy",
    			GTK_SIGNAL_FUNC (gtk_main_quit), NULL);
        gtk_container_set_border_width (GTK_CONTAINER (window), 10);
        gtk_widget_set_usize (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_paned_set_handle_size (GTK_PANED(vpaned),
                                   10);
        gtk_paned_set_gutter_size (GTK_PANED(vpaned),
                                   15);
        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;
    }
    /* example-end */

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