TCustomUpDown.OnChanging property
Event handler signalled prior to changing the value in the Position property.
Declaration
property OnChanging: TUDChangingEvent read FOnChanging write FOnChanging;Description
OnChanging is a
TUDChangingEvent property with the event
handler signalled prior to setting a new value for the Position property. The
handler include a Boolean AllowChange argument which indicates if a change to
the Position property is allowed in the control. Setting AllowChange to
False in the handler routine prevents a change from being applied to
the property value.
OnChanging is signalled (when assigned) from CanChange, and is used to get the return value for the method. It allows the application to accept or reject a change to Position using logic specific to the application.
Use OnChangingEx to implement an event handler which examines the new property value and direction (increase or decrease) for the changed value.
See also
An experiment, built from development snapshots. Not the official Free Pascal or Lazarus documentation.