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ComponentChangingEventArgs Class

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


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

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

The ComponentChangingEventArgs type exposes the following members.

Public methodComponentChangingEventArgsInitializes a new instance of the ComponentChangingEventArgs class.

Public propertyComponentGets 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.
Public propertyMemberGets the member that is about to be changed.

Public methodEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodToStringReturns 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.


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.

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

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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