This system-provided window procedure processes the actions on a slider control (WC_SLIDER).

Purpose

A slider control (WC_SLIDER window class) is a visual component whose specific purpose is to allow a user to set, display, or modify a value by moving a slider arm along a slider shaft. Sliders are typically used to allow a user to easily set values that have familiar increments, such as feet, inches, degrees, decibels, and so forth.

However, they can also be used for other purposes when immediate feedback is necessary, such as to blend colors or to show the percentage of a task that has completed. For example, an application might allow a user to mix and match color shades by moving a slider arm, or a read-only slider could be provided that shows how much of a task has completed by filling in the slider shaft as the task progresses. These are just a few examples to show you the many ways in which sliders can be used.

The appearance of and user interaction for a slider is similar to the appearance of and user interaction for a scroll bar. However, these two controls are not interchangeable because each has a distinct purpose. The scroll bar is used to scroll into view information that is outside a window's client area, while the slider is used to set, display, or modify that information, whether it is in the client area or not in the client area.

The slider is designed to be customizable to meet varying application requirements, while providing an easy-to-use user interface component that can be used to develop products that conform to the Common User Access (CUA) user interface guidelines. The application can specify different scales, sizes, and orientations for its sliders, but the underlying function of the control remains the same. For a complete description of CUA sliders, refer to the SAA CUA Guide to User Interface Design and the SAA CUA Advanced Interface Design Reference.