Announces to the component change service that a particular component is changing.
[Visual Basic] Sub OnComponentChanging( _ ByVal component As Object, _ ByVal member As MemberDescriptor _ ) [C#] void OnComponentChanging( object component, MemberDescriptor member ); [C++] void OnComponentChanging( Object* component, MemberDescriptor* member ); [JScript] function OnComponentChanging( component : Object, member : MemberDescriptor );
- The component that is about to change.
- The member that is changing. This is a null reference (Nothing in Visual Basic) if this change is not related to a single member.
This method raises the ComponentChanging event.
Most designers included with the .NET Framework SDK, as well as the Visual Studio .NET design-time environment, typically raise this event automatically, so most of the time, you do not need to explicitly call this method. The appropriate IComponentChangeService events are automatically raised when a PropertyDescriptor is used to change a property value or components are added or removed from the IDesignerHost container.
Notes to Implementers: This method throws an exception if the property cannot be changed. This is not intended to validate the values of a particular property. Instead, it is intended to provide a global method of preventing a component from changing. For example, if a designer file is checked into source code control, this event's handler would typically throw an exception if the user refused to check out the file.
Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family