ComAwareEventInfo.AddEventHandler(Object, Delegate) Method

Definition

Namespace:

System.Runtime.InteropServices

Assembly:

System.Runtime.InteropServices.dll

Source:

ComAwareEventInfo.cs

Attaches an event handler to a COM object.

public:
 override void AddEventHandler(System::Object ^ target, Delegate ^ handler);

[System.Runtime.Versioning.SupportedOSPlatform("windows")]
public override void AddEventHandler (object target, Delegate handler);

[<System.Runtime.Versioning.SupportedOSPlatform("windows")>]
override this.AddEventHandler : obj * Delegate -> unit

Public Overrides Sub AddEventHandler (target As Object, handler As Delegate)

Parameters

target

Object

The target object that the event delegate should bind to.

handler

Delegate

The event delegate.

Attributes

SupportedOSPlatformAttribute

Remarks

This method is similar to the EventInfo.AddEventHandler(Object, Delegate) method except that it allows you to attach events to COM objects.

If target is a COM object, this method adds a delegate to an event by using the ComEventsHelper.Combine(Object, Guid, Int32, Delegate) method.

AddEventHandler facilitates registering COM event sinks that forward calls to corresponding managed delegates. It requires the following information:

• The target object itself (target).

• The GUID of the source interface.

• The DispID of the method on the COM interface that corresponds to the specified event.

• The delegate that would be invoked when the COM object triggers the corresponding event (handler).

AddEventHandler looks up the corresponding COM source interface (specified as the first parameter of the ComEventInterfaceAttribute.ComEventInterfaceAttribute(Type, Type) constructor). It then looks up a method on the source interface whose name is identical to the event name. The value of GuidAttribute on the source interface is the GUID that is passed to ComEventsHelper.Combine(Object, Guid, Int32, Delegate); the value of DispIDAttribute on the method is the DispID value that is passed to ComEventsHelper.Combine(Object, Guid, Int32, Delegate).