ComponentChangingEventArgs Class


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Provides data for the ComponentChanging 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 ComponentChangingEventArgs : EventArgs

System_CAPS_pubmethodComponentChangingEventArgs(Object, MemberDescriptor)

Initializes a new instance of the ComponentChangingEventArgs class.


Gets the component that is about to be changed or the component that is the parent container of the member that is about to be changed.


Gets the member that is about to be changed.


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.)

ComponentChangingEventArgs provides data about a ComponentChanging event. The ComponentChanging event notifies the IComponentChangeService and registered event handlers that a particular component in the current design document is about to be changed. This event provides a widely accessible method to prevent a component from changing.

A ComponentChanging event is raised before a component is changed. This event provides an opportunity for a designer to abort the change. Component designers typically raise the ComponentChanging event automatically. If a property cannot be changed, the method that handles the event can throw an exception. For example, if a designer file is checked into source code control, the handler of this event typically throws an exception if the user refuses to check out the file.

A ComponentChangingEventArgs provides the following information:

  • A Component property that indicates the component that is about to be modified.

  • A Member property that indicates the member that is about to be changed.

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 ComponentChangingEventArgs.

// This example method creates a ComponentChangingEventArgs using the specified arguments.
// Typically, this type of event args is created by a design mode subsystem.  
public ComponentChangingEventArgs CreateComponentChangingEventArgs(object component, MemberDescriptor member)
    ComponentChangingEventArgs args = new ComponentChangingEventArgs(component, member);

    // The component that is about to change:       args.Component
    // The member that is about to change:          args.Member

    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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