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ComponentEventHandler Delegate

Represents the method that will handle the ComponentAdding, ComponentAdded, ComponentRemoving, and ComponentRemoved events raised for component-level events.

Namespace:  System.ComponentModel.Design
Assembly:  System (in System.dll)

[HostProtectionAttribute(SecurityAction.LinkDemand, SharedState = true)]
public delegate void ComponentEventHandler(
	Object sender,
	ComponentEventArgs e


Type: System.Object

The source of the event.

Type: System.ComponentModel.Design.ComponentEventArgs

A ComponentEventArgs that contains the event data.

When you create a ComponentEventHandler delegate, you identify the method that will handle the event. To associate the event with your event handler, add an instance of the delegate to the event. The event handler is called whenever the event occurs, unless you remove the delegate. For more information about event-handler delegates, see Events and Delegates.


The HostProtectionAttribute attribute applied to this type or member has the following Resources property value: SharedState. The HostProtectionAttribute does not affect desktop applications (which are typically started by double-clicking an icon, typing a command, or entering a URL in a browser). For more information, see the HostProtectionAttribute class or SQL Server Programming and Host Protection Attributes.

The following example demonstrates registering a ComponentEventHandler and handling the ComponentAdded, ComponentAdding, ComponentRemoved and ComponentRemoving events.

public void LinkComponentEvent(IComponentChangeService changeService)
    // Registers an event handler for the ComponentAdded, 
    // ComponentAdding, ComponentRemoved, and ComponentRemoving events.
    changeService.ComponentAdded += new ComponentEventHandler(this.OnComponentEvent);            
    changeService.ComponentAdding += new ComponentEventHandler(this.OnComponentEvent);            
    changeService.ComponentRemoved += new ComponentEventHandler(this.OnComponentEvent);            
    changeService.ComponentRemoving += new ComponentEventHandler(this.OnComponentEvent);                        

private void OnComponentEvent(object sender, ComponentEventArgs e)
    // Displays changed component information on the console.             
    if( e.Component.Site != null )
        Console.WriteLine("Name of the component related to the event: "+e.Component.Site.Name);      
    Console.WriteLine("Type of the component related to the event: "+e.Component.GetType().FullName);

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1
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