Scrollbar

The Scrollbar control allows the user to scroll an image or other view that is too large to see completely. Note that the similar Slider control is used for selecting numeric values rather than scrolling. Familiar examples include the vertical Scrollbar at the side of a text editor and the vertical and horizontal pair of bars for viewing a section of a large image or map.

Свойства

Events

Детали

The value of a Scrollbar is determined by the position of the handle along its length with the value being reported as a fraction between the extreme ends. For example, the default left-to-right bar has a value of 0.0 at the left end, 1.0 at the right end and 0.5 indicates the halfway point. A scrollbar can be oriented vertically by choosing Top To Bottom or Bottom To Top for the Direction property.

A significant difference between the Scrollbar and the similar Slider control is that the Scrollbar’s handle can change in size to represent the distance of scrolling available; when the view can scroll only a short way, the handle will fill up most of the bar and only allow a slight shift either direction.

The Scrollbar has a single event called On Value Changed that responds as the user drags the handle. The current value is passed to the even function as a float parameter. Typical use cases for a scrollbar include:

• Scrolling a piece of text vertically.
• Scrolling a timeline horizontally.
• Used as a pair, scrolling a large image both horizontally and vertically to view a zoomed section. The size of the handle changes to indicate the degree of zooming and therefore the available distance for scrolling.