IconTheme provides a facility for looking up icons by name and size.
The main reason for using a name rather than simply providing a filename is to allow different icons to be used depending on what
“icon theme” is selected by the user. The operation of icon themes on Linux and Unix follows the
Icon Theme Specification There is a fallback icon
theme, named `hicolor`, where applications should install their icons, but additional icon themes can be installed as operating system
vendors and users choose.
Named icons are similar to the deprecated Stock Items, and the distinction between the two may be a bit confusing. A few things to
keep in mind:
- Stock images usually are used in conjunction with Stock Items, such as gtk_stock_ok or
gtk_stock_open. Named icons are easier to set up and therefore are more useful for new icons that an
application wants to add, such as application icons or window icons.
- Stock images can only be loaded at the symbolic sizes defined by the IconSize
enumeration, or by custom sizes defined by register, while named icons
are more flexible and any pixel size can be specified.
- Because stock images are closely tied to stock items, and thus to actions in the user interface, stock images may come in multiple
variants for different widget states or writing directions.
A good rule of thumb is that if there is a stock image for what you want to use, use it, otherwise use a named icon. It turns out that
internally stock images are generally defined in terms of one or more named icons. (An example of the more than one case is icons that
depend on writing direction; gtk_stock_go_forward uses the two themed icons
“gtk-stock-go-forward-ltr” and “gtk-stock-go-forward-rtl”.)
In many cases, named themes are used indirectly, via Image or stock items, rather than
directly, but looking up icons directly is also simple. The IconTheme object acts as a database of all the
icons in the current theme. You can create new IconTheme objects, but it’s much more efficient to use the
standard icon theme for the Screen so that the icon information is shared with other people looking up icons.
GError *error = NULL;
GtkIconTheme *icon_theme;
GdkPixbuf *pixbuf;
icon_theme = gtk_icon_theme_get_default ();
pixbuf = gtk_icon_theme_load_icon (icon_theme,
"my-icon-name", // icon name
48, // icon size
0, // flags
&error);
if (!pixbuf)
{
g_warning ("Couldn’t load icon: %s", error->message);
g_error_free (error);
}
else
{
// Use the pixbuf
g_object_unref (pixbuf);
}
Example: IconTheme:

public class Application : Gtk.Window {
public Application () {
// Prepare Gtk.Window:
this.title = "My Gtk.IconTheme";
this.window_position = Gtk.WindowPosition.CENTER;
this.destroy.connect (Gtk.main_quit);
// Add a button
Gtk.Button button = new Gtk.Button ();
this.add (button);
// Get the icon:
Gtk.IconTheme icon_theme = Gtk.IconTheme.get_default ();
try {
Gdk.Pixbuf icon = icon_theme.load_icon ("go-home", 48, 0);
button.image = new Gtk.Image.from_pixbuf (icon);
} catch (Error e) {
warning (e.message);
}
}
public static int main (string[] args) {
Gtk.init (ref args);
Application app = new Application ();
app.show_all ();
Gtk.main ();
return 0;
}
}
valac --pkg gtk+-3.0 Gtk.IconTheme.vala
- public void add_resource_path (string path)
Adds a resource path that will be looked at when looking for icons,
similar to search paths.
- public void append_search_path (string path)
Appends a directory to the search path.
- public IconInfo? choose_icon (string[] icon_names, int size, IconLookupFlags flags)
Looks up a named icon and returns a
IconInfo containing information such as the filename of the icon.
- public IconInfo? choose_icon_for_scale (string[] icon_names, int size, int scale, IconLookupFlags flags)
Looks up a named icon for a particular window scale and returns a
IconInfo containing information such as the filename of the icon.
- public string? get_example_icon_name ()
Gets the name of an icon that is representative of the current theme (
for instance, to use when presenting a list of themes to the user.
- public int[] get_icon_sizes (string icon_name)
Returns an array of integers describing the sizes at which the icon is
available without scaling.
- public void get_search_path (out string[] path)
Gets the current search path.
- public bool has_icon (string icon_name)
Checks whether an icon theme includes an icon for a particular name.
- public List<string> list_contexts ()
Gets the list of contexts available within the current hierarchy of
icon themes.
- public List<string> list_icons (string? context)
Lists the icons in the current icon theme.
- public Pixbuf? load_icon (string icon_name, int size, IconLookupFlags flags) throws Error
Looks up an icon in an icon theme, scales it to the given size and
renders it into a pixbuf.
- public Pixbuf? load_icon_for_scale (string icon_name, int size, int scale, IconLookupFlags flags) throws Error
Looks up an icon in an icon theme for a particular window scale,
scales it to the given size and renders it into a pixbuf.
- public Surface? load_surface (string icon_name, int size, int scale, Window? for_window, IconLookupFlags flags) throws Error
Looks up an icon in an icon theme for a particular window scale,
scales it to the given size and renders it into a cairo surface.
- public IconInfo? lookup_by_gicon (Icon icon, int size, IconLookupFlags flags)
Looks up an icon and returns a
IconInfo containing information such as the filename of the icon.
- public IconInfo? lookup_by_gicon_for_scale (Icon icon, int size, int scale, IconLookupFlags flags)
Looks up an icon and returns a
IconInfo containing information such as the filename of the icon.
- public IconInfo? lookup_icon (string icon_name, int size, IconLookupFlags flags)
Looks up a named icon and returns a
IconInfo containing information such as the filename of the icon.
- public IconInfo? lookup_icon_for_scale (string icon_name, int size, int scale, IconLookupFlags flags)
Looks up a named icon for a particular window scale and returns a
IconInfo containing information such as the filename of the icon.
- public void prepend_search_path (string path)
Prepends a directory to the search path.
- public bool rescan_if_needed ()
Checks to see if the icon theme has changed; if it has, any currently
cached information is discarded and will be reloaded next time this is accessed.
- public void set_custom_theme (string? theme_name)
Sets the name of the icon theme that the IconTheme
object uses overriding system configuration.
- public void set_screen (Screen screen)
Sets the screen for an icon theme; the screen is used to track the
user’s currently configured icon theme, which might be different for different screens.
- public void set_search_path (string[] path)
Sets the search path for the icon theme object.