GtkFileChooser
**************

File chooser interface used by GtkFileChooserWidget and GtkFileChooserDialog

Overview
========

<gtk-file-chooser> is an interface that can be implemented by file selection widgets. In GTK+, the main objects that implement this interface are <gtk-file-chooser-widget>, <gtk-file-chooser-dialog>, and <gtk-file-chooser-button>. You do not need to write an object that implements the <gtk-file-chooser> interface unless you are trying to adapt an existing file selector to expose a standard programming interface.

<gtk-file-chooser> allows for shortcuts to various places in the filesystem. In the default implementation these are displayed in the left pane. It may be a bit confusing at first taht these shortcuts come from various sources and in various flavours, so lets explain the terminology here:

Shortcuts

Volumes

are created by the user, by dragging folders from the right pane to the left pane, or by using the "Add". Bookmarks can be renamed and deleted by the user.

can be provided by the application or by the underlying filesystem abstraction (e.g. both the gnome-vfs and the Windows filesystems provide "Desktop" shortcuts). Shortcuts cannot be modified by the user.

are provided by the underlying filesystem abstraction. They are the "roots" of the filesystem.

File Names and Encodings
========================

When the user is finished selecting files in a <gtk-file-chooser>, your program can get the selected names either as filenames or as URIs. For URIs, the normal escaping rules are applied if the URI contains non-ASCII characters. However, filenames are always returned in the character set specified by the G_FILENAME_ENCODING environment variable. Please see the Glib documentation for more details about this variable.

This means that while you can pass the result of gtk-file-chooser-get-filename to open(2) or fopen(3), you may not be able to directly set it as the text of a <gtk-label> widget unless you convert it first to UTF-8, which all GTK+ widgets expect. You should use g-filename-to-utf8 to convert filenames into strings that can be passed to GTK+ widgets.

Adding a Preview Widget
=======================

You can add a custom preview widget to a file chooser and then get notification about when the preview needs to be updated. To install a preview widget, use gtk-file-chooser-set-preview-widget. Then, connect to the <gtk-file-chooser::update-preview> signal to get notified when you need to update the contents of the preview.

Your callback should use gtk-file-chooser-get-preview-filename to see what needs previewing. Once you have generated the preview for the corresponding file, you must call gtk-file-chooser-set-preview-widget-active with a boolean flag that indicates whether your callback could successfully generate a preview.

     {
       GtkImage *preview;

       ...

       preview = gtk_image_new ();

       gtk_file_chooser_set_preview_widget (my_file_chooser, preview);
       g_signal_connect (my_file_chooser, "update-preview",
     		    G_CALLBACK (update_preview_cb), preview);
     }

     static void
     update_preview_cb (GtkFileChooser *file_chooser, gpointer data)
     {
       GtkWidget *preview;
       char *filename;
       GdkPixbuf *pixbuf;
       gboolean have_preview;

       preview = GTK_WIDGET (data);
       filename = gtk_file_chooser_get_preview_filename (file_chooser);

       pixbuf = gdk_pixbuf_new_from_file_at_size (filename, 128, 128, NULL);
       have_preview = (pixbuf != NULL);
       g_free (filename);

       gtk_image_set_from_pixbuf (GTK_IMAGE (preview), pixbuf);
       if (pixbuf)
         gobject_unref (pixbuf);

       gtk_file_chooser_set_preview_widget_active (file_chooser, have_preview);
     }

Adding Extra Widgets
====================

You can add extra widgets to a file chooser to provide options that are not present in the default design. For example, you can add a toggle button to give the user the option to open a file in read-only mode. You can use gtk-file-chooser-set-extra-widget to insert additional widgets in a file chooser.

     {
       GtkWidget *toggle;

       ...

       toggle = gtk_check_button_new_with_label ("Open file read-only");
       gtk_widget_show (toggle);
       gtk_file_chooser_set_extra_widget (my_file_chooser, toggle);
     }

If you want to set more than one extra widget in the file chooser, you can a container such as a GtkVBox or a GtkTable and include your widgets in it. Then, set the container as the whole extra widget.

Key Bindings
============

Internally, GTK+ implements a file chooser's graphical user interface with the private . This widget has several key bindings and their associated signals. This section describes the available key binding signals.

The default keys that activate the key-binding signals in are as follows:

Both the individual key and the numeric keypad's "divide" key are supported.

Both the individual Up key and the numeric keypad's Up key are supported.

You can change these defaults to something else. For example, to add a modifier to a few of the default bindings, you can include the following fragment in your .gtkrc-2.0 file:

     binding "my-own-gtkfilechooser-bindings" {
     	bind "<Alt><Shift>Up" {
     		"up-folder" ()
     	}
     	bind "<Alt><Shift>Down" {
     		"down-folder" ()
     	}
     	bind "<Alt><Shift>Home" {
     		"home-folder" ()
     	}
     }

     class "GtkFileChooserDefault" binding "my-own-gtkfilechooser-bindings"

The "GtkFileChooserDefault::location-popup" signal
--------------------------------------------------

               void user_function (GtkFileChooserDefault *chooser,
                                   const char            *path,
                                   gpointer user_data);

This is used to make the file chooser show a "Location" dialog which the user can use to manually type the name of the file he wishes to select. The PATH argument is a string that gets put in the text entry for the file name. By default this is bound to with a PATH string of "" (the empty string). It is also bound to with a PATH string of "/" (a slash): this lets you type and immediately type a path name. On Unix systems, this is bound to (tilde) with a PATH string of "~" itself for access to home directories.

chooser
     the object which received the signal.

path
     default contents for the text entry for the file name

user-data
     user data set when the signal handler was connected.

You can create your own bindings for the signal with custom PATH strings, and have a crude form of easily-to-type bookmarks. For example, say you access the path /home/username/misc very frequently. You could then create an shortcut by including the following in your .gtkrc-2.0:

     binding "misc-shortcut" {
     	bind "<Alt>M" {
     		"location-popup" ("/home/username/misc")
     	}
     }

     class "GtkFileChooserDefault" binding "misc-shortcut"

The "GtkFileChooserDefault::up-folder" signal
---------------------------------------------

               void user_function (GtkFileChooserDefault *chooser,
                                   gpointer user_data);

This is used to make the file chooser go to the parent of the current folder in the file hierarchy. By default this is bound to and (the Up key in the numeric keypad also works).

chooser
     the object which received the signal.

user-data
     user data set when the signal handler was connected.

The "GtkFileChooserDefault::down-folder" signal
-----------------------------------------------

               void user_function (GtkFileChooserDefault *chooser,
                                   gpointer user_data);

This is used to make the file chooser go to a child of the current folder in the file hierarchy. The subfolder that will be used is displayed in the path bar widget of the file chooser. For example, if the path bar is showing "/foo/bar/baz", then this will cause the file chooser to switch to the "baz" subfolder. By default this is bound to (the Down key in the numeric keypad also works).

chooser
     the object which received the signal.

user-data
     user data set when the signal handler was connected.

The "GtkFileChooserDefault::home-folder" signal
-----------------------------------------------

               void user_function (GtkFileChooserDefault *chooser,
                                   gpointer user_data);

This is used to make the file chooser show the user's home folder in the file list. By default this is bound to (the Home key in the numeric keypad also works).

chooser
     the object which received the signal.

user-data
     user data set when the signal handler was connected.

The "GtkFileChooserDefault::desktop-folder" signal
--------------------------------------------------

               void user_function (GtkFileChooserDefault *chooser,
                                   gpointer user_data);

This is used to make the file chooser show the user's Desktop folder in the file list. By default this is bound to .

chooser
     the object which received the signal.

user-data
     user data set when the signal handler was connected.

The "GtkFileChooserDefault::quick-bookmark" signal
--------------------------------------------------

               void user_function (GtkFileChooserDefault *chooser,
                                   gint bookmark_index,
                                   gpointer user_data);

This is used to make the file chooser switch to the bookmark specified in the BOOKMARK-INDEX parameter. For example, if you have three bookmarks, you can pass 0, 1, 2 to this signal to switch to each of them, respectively. By default this is bound to , , etc. until . Note that in the default binding, that is actually defined to switch to the bookmark at index 0, and so on successively; is defined to switch to the bookmark at index 10.

chooser
     the object which received the signal.

bookmark-indes
     index of the bookmark to switch to; the indices start at 0.

user-data
     user data set when the signal handler was connected.

Usage
=====

     [file defuns-gtkfilechooser.xml.texi not included]