ComponentChangedEventArgs Class
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ComponentChangedEventArgs Class


Provides data for the ComponentChanged event. This class cannot be inherited.

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


[HostProtectionAttribute(SecurityAction.LinkDemand, SharedState = true)]
[PermissionSetAttribute(SecurityAction.LinkDemand, Name = "FullTrust")]
public sealed class ComponentChangedEventArgs : EventArgs

System_CAPS_pubmethodComponentChangedEventArgs(Object, MemberDescriptor, Object, Object)

Initializes a new instance of the ComponentChangedEventArgs class.


Gets the component that was modified.


Gets the member that has been changed.


Gets the new value of the changed member.


Gets the old value of the changed member.


Determines whether the specified object is equal to the current object.(Inherited from Object.)


Serves as the default hash function. (Inherited from Object.)


Gets the Type of the current instance.(Inherited from Object.)


Returns a string that represents the current object.(Inherited from Object.)

ComponentChangedEventArgs provides data for a ComponentChanged event. The ComponentChanged event notifies the IComponentChangeService and registered event handlers that a particular component in the currently active document has been changed.

A ComponentChangedEventArgs provides the following information:

  • A Component property that indicates the component that was modified.

  • A Member property that indicates the member that was changed.

  • A NewValue property that indicates the new value of the member.

  • An OldValue property that indicates the old value of the member.

Component designers typically raise the ComponentChanged event automatically when components are added, removed, or modified. A ComponentChanged event is not raised during form load and unload because changes at this time are expected. A component designer might raise the ComponentChanged event after it changes a property of the component; this ensures that the Properties window will display the updated property.

Notes to Inheritors:

A compiler error occurs if this class is specified as the base class of another class.

The following example demonstrates creating a ComponentChangedEventArgs.

// This example method creates a ComponentChangedEventArgs using the specified arguments.
// Typically, this type of event args is created by a design mode subsystem.            
public ComponentChangedEventArgs CreateComponentChangedEventArgs(object component, MemberDescriptor member, object oldValue, object newValue)
    // Creates a component changed event args with the specified arguments.
    ComponentChangedEventArgs args = new ComponentChangedEventArgs(component, member, oldValue, newValue);

    // The component that has changed:              args.Component
    // The member of the component that changed:    args.Member
    // The old value of the member:                 args.oldValue
    // The new value of the member:                 args.newValue

    return args;            

.NET Framework
Available since 1.1

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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