Object Hierarchy:

Object hierarchy for LevelBar


public class LevelBar : Widget, Implementor, Buildable, Orientable

The LevelBar is a bar widget that can be used as a level indicator.

Typical use cases are displaying the strength of a password, or showing the charge level of a battery.

Use set_value to set the current value, and add_offset_value to set the value offsets at which the bar will be considered in a different state. GTK will add a few offsets by default on the level bar: LEVEL_BAR_OFFSET_LOW, LEVEL_BAR_OFFSET_HIGH and LEVEL_BAR_OFFSET_FULL, with values 0.25, 0.75 and 1.0 respectively.

Note that it is your responsibility to update preexisting offsets when changing the minimum or maximum value. GTK+ will simply clamp them to the new range.

Adding a custom offset on the bar

static GtkWidget *
create_level_bar (void)
GtkWidget *widget;
GtkLevelBar *bar;

widget = gtk_level_bar_new ();
bar = GTK_LEVEL_BAR (widget);

// This changes the value of the default low offset

gtk_level_bar_add_offset_value (bar,

// This adds a new offset to the bar; the application will
// be able to change its color CSS like this:
// levelbar block.my-offset {
// background-color: magenta;
// border-style: solid;
// border-color: black;
// border-style: 1px;
// }

gtk_level_bar_add_offset_value (bar, "my-offset", 0.60);

return widget;

The default interval of values is between zero and one, but it’s possible to modify the interval using set_min_value and set_max_value. The value will be always drawn in proportion to the admissible interval, i.e. a value of 15 with a specified interval between 10 and 20 is equivalent to a value of 0.5 with an interval between 0 and 1. When DISCRETE is used, the bar level is rendered as a finite number of separated blocks instead of a single one. The number of blocks that will be rendered is equal to the number of units specified by the admissible interval.

For instance, to build a bar rendered with five blocks, it’s sufficient to set the minimum value to 0 and the maximum value to 5 after changing the indicator mode to discrete.

GtkLevelBar was introduced in GTK+ 3.6.

GtkLevelBar as GtkBuildable

The GtkLevelBar implementation of the GtkBuildable interface supports a custom <offsets> element, which can contain any number of < offset> elements, each of which must have name and value attributes.

CSS nodes

╰── trough
├── block.filled.level-name

├── block.empty
in CSS node with name levelbar and one of the style classes .discrete or .continuous and a subnode with name trough. Below the trough node are a number of nodes with name block and style class .filled or .empty. In continuous mode, there is exactly one node of each, in discrete mode, the number of filled and unfilled nodes corresponds to blocks that are drawn. The block.filled nodes also get a style class .level-name corresponding to the level for the current value.

In horizontal orientation, the nodes are always arranged from left to right, regardless of text direction.


Example: LevelBar:

public class Application : Gtk.Window {
public Application () {
// Prepare Gtk.Window:
this.title = "My Gtk.LevelBar";
this.window_position = Gtk.WindowPosition.CENTER;
this.destroy.connect (Gtk.main_quit);

// The ProgressBar:
Gtk.LevelBar bar = new Gtk.LevelBar.for_interval (0.0, 10.0);
bar.set_mode (Gtk.LevelBarMode.DISCRETE);
bar.set_value (5.0);
this.add (bar);

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.LevelBar.vala

Namespace: Gtk
Package: gtk+-3.0



Creation methods:



Inherited Members:

All known members inherited from class Gtk.Widget
All known members inherited from interface Atk.Implementor
All known members inherited from interface Gtk.Orientable