trackbar

A trackbar, commonly referred to as a slider, is a graphical user interface control that allows users to select a value from a defined range by moving a handle along a track. The control is typically horizontal but can also be oriented vertically. It exposes a minimum value, a maximum value, and a current position, and may include a step size and optional tick marks to indicate divisions. Some implementations update dependent displays in real time as the handle is moved, while others apply changes only after the user releases the handle.

Users interact with a trackbar by dragging the handle, clicking on the track to jump, or using keyboard input such as arrow keys for small changes or page up/down for larger steps. Applications usually respond to value-change events or callbacks, allowing immediate or deferred updates to settings, calculations, or visualizations.

Trackbars are a standard component across many GUI toolkits and platforms. They appear as the Windows trackbar control, as sliders in Qt or GTK, and as range controls in web interfaces (for example, HTML input elements of type range). While appearance and event models vary by framework, the core concept remains the same: a user-selectable numeric value within a specified range via a movable handle.

Common uses include adjusting parameters in dialogs or panels, such as volume, brightness, color thresholds in image processing, or any scenario requiring quick, incremental tuning with immediate feedback. See also: slider, GUI control.