`GtkLevelBar` is a 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 [[email protected]_value] to set the current value, and [[email protected]_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:
gtk_level_bar_offset_low, gtk_level_bar_offset_high and
gtk_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
```c 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 [
[email protected]_min_value] and [[email protected]_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 gtk_level_bar_mode_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 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 ┊ ```
`GtkLevelBar` has a main 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.
Accessibility
`GtkLevelBar` uses the gtk_accessible_role_meter role.