GtkScale

GtkScale is a widget in the GTK toolkit that provides a slider for selecting a numeric value within a defined range. It acts as the base class for concrete scale widgets such as GtkHScale (horizontal) and GtkVScale (vertical) and is built on top of GtkRange, the common foundation for range-based controls. GtkScale itself handles the core logic for mapping a value to a position along a track and for handling input from the user.

Internally, GtkScale relies on a GtkAdjustment object to represent the value range: the lower and upper bounds, the current value, and the step and page increments used when the user moves the handle. This separation allows the same widget to be reused across different orientations and applications. The appearance and behavior of the scale can be customized with properties such as digits (for decimal precision) and options controlling how the current value is presented.

User interaction includes dragging the slider handle with a mouse or touch, using keyboard input to step the value, or clicking in the trough to move by larger increments. When the value changes, GtkScale typically emits a value-changed signal, enabling application code to react and update related UI or data.

GtkScale supports accessibility features and keyboard focus, making it usable in a variety of desktop environments. It is commonly employed in settings dialogs, media controls, and any interface requiring precise or bounded numeric input. Constructing a scale usually involves creating a horizontal or vertical variant (or a base scale in some versions) and associating it with an adjustment describing its range and current value.