[Overview][Constants][Types][Classes][Procedures and functions][Variables][Index] | Reference for unit 'Forms' (#lcl)

# TControlScrollBar.UpdateScrollBar

Updates the state and position for the scroll bar on the associated control.

## Declaration

Source position: forms.pp line 135

`protected procedure TControlScrollBar.UpdateScrollBar; virtual;`

## Description

UpdateScrollBar is a procedure used to update the state and position for the scroll bar on the associated control.

If the associated control is a TScrollingWinControl instance, TScrollInfo is captured using the Range, Position, and Page properties. The scroll bar information is applied to the associated control by calling SetScrollInfo. The visibility for the scroll bar is updated by calling ShowScrollBar.

Remark: | TScrollInfo values and visibility are not applied when a handle has not been allocated for the control, when the scroll information has not been changed, or when when the control is not a TScrollingWinControl class instance.

UpdateScrollBar applies the current value in Position to a visible scroll bar in the class instance. If the associated control is a TScrollingWinControl instance, the Smooth property is used to determine whether Increment needs to be adjusted to a value that is 10% of the Page size for the control. Increment is not modified if Smooth is set to False.

UpdateScrollBar is used in the implementation of the ControlUpdateScrollBars method.

## Version info

Modified in LCL version 3.0 to omit updates to scroll bar information if the values have not been changed.

## See also

TControlScrollBar.Increment |  | Number of pixels the display area is scrolled for scroll bar or mouse wheel movements.
TControlScrollBar.Page |  | Number of pixels needed for a page on the associated control.
TControlScrollBar.Position |  | Position of the scroll bar slider in the range 0..Range-Page.
TControlScrollBar.Smooth |  | Enables smooth scrolling, with automatic adjustment of Increment and Page.
TControlScrollBar.Range |  | The size of the logical display area on the associated control for the scroll bar orientation.
TControlScrollBar.Visible |  | Hides the scroll bar when False (default True).
TControlScrollBar.ControlUpdateScrollBars |  | Forces the associated control to update its scroll bars.