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,
GTK_LEVEL_BAR_OFFSET_LOW,
0.10);
// 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
levelbar[.discrete]
╰── 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.
