IComponentChangeService Interface

Provides an interface to add and remove the event handlers for events that add, change, remove or rename components, and provides methods to raise a ComponentChanged or ComponentChanging event.

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

'Declaration
<ComVisibleAttribute(True)> _
Public Interface IComponentChangeService
'Usage
Dim instance As IComponentChangeService

/** @attribute ComVisibleAttribute(true) */ 
public interface IComponentChangeService
ComVisibleAttribute(true) 
public interface IComponentChangeService
Not applicable.

IComponentChangeService provides an interface that can be used to indicate the methods that handle the following events:

  • ComponentAdded, raised when a component is added.

  • ComponentAdding, raised when a component is about to be added.

  • ComponentChanged, raised when a component is changed.

  • ComponentChanging, raised when a component is about to be changed.

  • ComponentRemoved, raised when a component is removed.

  • ComponentRemoving, raised when a component is about to be removed.

  • ComponentRename, raised when a component is renamed.

Typically, the design environment raises these component add, change, remove, or rename events. Designers should call the methods of this interface when using DesignerTransaction objects to provide undo and redo functionality for design-time actions that affect components. More information is available in the documentation for DesignerTransaction. Generally, only the root designer handles these change notifications.

This service also provides methods that raise a component changed event or component changing event. A PropertyDescriptor or a component can indicate that a component has changed or is changing with the OnComponentChanged and OnComponentChanging methods, respectively.

This following example demonstrates how to use the IComponentChangeService interface to receive notifications about the addition of, removal of, and changes to components in design mode.

Imports System
Imports System.Data
Imports System.Drawing
Imports System.Collections
Imports System.ComponentModel
Imports System.ComponentModel.Design
Imports System.Windows.Forms

'  This sample illustrates how to use the IComponentChangeService interface 
'    to handle component change events.  The ComponentClass control attaches 
'    event handlers when it is sited in a document, and displays a message 
'    when notification that a component has been added, removed, or changed
'    is received from the IComponentChangeService.

'    To run this sample, add the ComponentClass control to a Form and
'    add, remove, or change components to see the behavior of the
'    component change event handlers. 

Namespace IComponentChangeServiceExample
    _
   Public Class ComponentClass
      Inherits System.Windows.Forms.UserControl
      Private components As System.ComponentModel.Container = Nothing
      Private listBox1 As System.Windows.Forms.ListBox
      Private m_changeService As IComponentChangeService    
      
      Public Sub New()
         InitializeComponent()
        End Sub

        Private Sub InitializeComponent()
            Me.listBox1 = New System.Windows.Forms.ListBox()
            Me.SuspendLayout()

            ' listBox1.
            Me.listBox1.Location = New System.Drawing.Point(24, 16)
            Me.listBox1.Name = "listBox1"
            Me.listBox1.Size = New System.Drawing.Size(576, 277)
            Me.listBox1.TabIndex = 0

            ' ComponentClass.
            Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.listBox1})
            Me.Name = "ComponentClass"
            Me.Size = New System.Drawing.Size(624, 320)

            Me.ResumeLayout(False)
        End Sub

        ' This override allows the control to register event handlers for IComponentChangeService events
        ' at the time the control is sited, which happens only in design mode.
        Public Overrides Property Site() As ISite
            Get
                Return MyBase.Site
            End Get
            Set(ByVal Value As ISite)
                ' Clear any component change event handlers.
                ClearChangeNotifications()

                ' Set the new Site value.
                MyBase.Site = Value

                m_changeService = CType(GetService(GetType(IComponentChangeService)), IComponentChangeService)

                ' Register event handlers for component change events.
                RegisterChangeNotifications()
            End Set
        End Property

        Private Sub ClearChangeNotifications()
            ' The m_changeService value is null when not in design mode, 
            ' as the IComponentChangeService is only available at design time.	
            m_changeService = CType(GetService(GetType(IComponentChangeService)), IComponentChangeService)

            ' Clear our the component change events to prepare for re-siting.				
            If (m_changeService IsNot Nothing) Then
                RemoveHandler m_changeService.ComponentChanged, AddressOf OnComponentChanged
                RemoveHandler m_changeService.ComponentChanging, AddressOf OnComponentChanging
                RemoveHandler m_changeService.ComponentAdded, AddressOf OnComponentAdded
                RemoveHandler m_changeService.ComponentAdding, AddressOf OnComponentAdding
                RemoveHandler m_changeService.ComponentRemoved, AddressOf OnComponentRemoved
                RemoveHandler m_changeService.ComponentRemoving, AddressOf OnComponentRemoving
                RemoveHandler m_changeService.ComponentRename, AddressOf OnComponentRename
            End If
        End Sub

        Private Sub RegisterChangeNotifications()
            ' Register the event handlers for the IComponentChangeService events
            If (m_changeService IsNot Nothing) Then
                AddHandler m_changeService.ComponentChanged, AddressOf OnComponentChanged
                AddHandler m_changeService.ComponentChanging, AddressOf OnComponentChanging
                AddHandler m_changeService.ComponentAdded, AddressOf OnComponentAdded
                AddHandler m_changeService.ComponentAdding, AddressOf OnComponentAdding
                AddHandler m_changeService.ComponentRemoved, AddressOf OnComponentRemoved
                AddHandler m_changeService.ComponentRemoving, AddressOf OnComponentRemoving
                AddHandler m_changeService.ComponentRename, AddressOf OnComponentRename
            End If
        End Sub

        ' This method handles the OnComponentChanged event to display a notification. 
        Private Sub OnComponentChanged(ByVal sender As Object, ByVal ce As ComponentChangedEventArgs)
            If (ce.Component IsNot Nothing) And (CType(ce.Component, IComponent).Site IsNot Nothing) And (ce.Member IsNot Nothing) Then
                OnUserChange(("The " + ce.Member.Name + " member of the " + CType(ce.Component, IComponent).Site.Name + " component has been changed."))
            End If
        End Sub

        ' This method handles the OnComponentChanging event to display a notification. 
        Private Sub OnComponentChanging(ByVal sender As Object, ByVal ce As ComponentChangingEventArgs)
            If (ce.Component IsNot Nothing) And (CType(ce.Component, IComponent).Site IsNot Nothing) And (ce.Member IsNot Nothing) Then
                OnUserChange(("The " + ce.Member.Name + " member of the " + CType(ce.Component, IComponent).Site.Name + " component is being changed."))
            End If
        End Sub

        ' This method handles the OnComponentAdded event to display a notification. 
        Private Sub OnComponentAdded(ByVal sender As Object, ByVal ce As ComponentEventArgs)
            OnUserChange(("A component, " + ce.Component.Site.Name + ", has been added."))
        End Sub

        ' This method handles the OnComponentAdding event to display a notification. 
        Private Sub OnComponentAdding(ByVal sender As Object, ByVal ce As ComponentEventArgs)
            OnUserChange(("A component of type " + (CType(ce.Component, Component)).GetType().FullName + " is being added."))
        End Sub

        ' This method handles the OnComponentRemoved event to display a notification. 
        Private Sub OnComponentRemoved(ByVal sender As Object, ByVal ce As ComponentEventArgs)
            OnUserChange(("A component, " + ce.Component.Site.Name + ", has been removed."))
        End Sub

        ' This method handles the OnComponentRemoving event to display a notification. 
        Private Sub OnComponentRemoving(ByVal sender As Object, ByVal ce As ComponentEventArgs)
            OnUserChange(("A component, " + ce.Component.Site.Name + ", is being removed."))
        End Sub

        ' This method handles the OnComponentRename event to display a notification. 
        Private Sub OnComponentRename(ByVal sender As Object, ByVal ce As ComponentRenameEventArgs)
            OnUserChange(("A component, " + ce.OldName + ", was renamed to " + ce.NewName + "."))
        End Sub

        ' This method adds a specified notification message to the control's listbox.
        Private Sub OnUserChange(ByVal [text] As String)
            listBox1.Items.Add([text])
        End Sub

        ' Clean up any resources being used.
        Protected Overloads Sub Dispose(ByVal disposing As Boolean)
            If disposing Then
                ClearChangeNotifications()

                If (components IsNot Nothing) Then
                    components.Dispose()
                End If
            End If
            MyBase.Dispose(disposing)
        End Sub

    End Class
End Namespace

import System.*;
import System.Data.*;
import System.Drawing.*;
import System.Collections.*;
import System.ComponentModel.*;
import System.ComponentModel.Design.*;
import System.Windows.Forms.*;

/*  This sample illustrates how to use the IComponentChangeService interface
    to handle component change events.  The ComponentClass control attaches 
    event handlers when it is sited in a document, and displays a message 
    when notification that a component has been added, removed, or changed
    is received from the IComponentChangeService.

    To run this sample, add the ComponentClass control to a Form and
    add, remove, or change components to see the behavior of the
    component change event handlers. 
 */

public class ComponentClass extends System.Windows.Forms.UserControl
{
    private System.ComponentModel.Container components = null;
    private System.Windows.Forms.ListBox listBox1;
    private IComponentChangeService m_changeService;

    public ComponentClass()
    {
        InitializeComponent();
    } //ComponentClass

    private void InitializeComponent()
    {
        this.listBox1 = new System.Windows.Forms.ListBox();
        this.SuspendLayout();

        // listBox1.
        this.listBox1.set_Location(new System.Drawing.Point(24,16));
        this.listBox1.set_Name("listBox1");
        this.listBox1.set_Size(new System.Drawing.Size(576, 277));
        this.listBox1.set_TabIndex(0);

        // ComponentClass.
        this.get_Controls().AddRange(new 
            System.Windows.Forms.Control[] {this.listBox1 });
        this.set_Name("ComponentClass");
        this.set_Size(new System.Drawing.Size(624, 320));
        this.ResumeLayout(false);
    } //InitializeComponent

    // This override allows the control to register event handlers for 
    // IComponentChangeService events
    // at the time the control is sited, which happens only in design mode.
    /** @property
     */
    public ISite get_Site()
    {
        return super.get_Site();
    } //get_Site

    /** @property 
     */
    public void set_Site(ISite value)
    {
        // Clear any component change event handlers.
        ClearChangeNotifications();

        // Set the new Site value.
        super.set_Site(value);
        m_changeService = (IComponentChangeService)
            GetService(IComponentChangeService.class.ToType());
        // Register event handlers for component change events.
        RegisterChangeNotifications();
    } //set_Site

    private void ClearChangeNotifications()
    {
        // The m_changeService value is null when not in design mode, 
        // as the IComponentChangeService is only available at design time.
        m_changeService = (IComponentChangeService)
            GetService(IComponentChangeService.class.ToType());

        // Clear our the component change events to prepare for re-siting.            
        if (m_changeService != null) {
            m_changeService.remove_ComponentChanged(new 
                ComponentChangedEventHandler(OnComponentChanged));
            m_changeService.remove_ComponentChanging(new 
                ComponentChangingEventHandler(OnComponentChanging));
            m_changeService.remove_ComponentAdded(new 
                ComponentEventHandler(OnComponentAdded));
            m_changeService.remove_ComponentAdding(new 
                ComponentEventHandler(OnComponentAdding));
            m_changeService.remove_ComponentRemoved(new 
                ComponentEventHandler(OnComponentRemoved));
            m_changeService.remove_ComponentRemoving(new 
                ComponentEventHandler(OnComponentRemoving));
            m_changeService.remove_ComponentRename(new 
                ComponentRenameEventHandler(OnComponentRename));
        }
    } //ClearChangeNotifications

    private void RegisterChangeNotifications()
    {
        // Register the event handlers for the IComponentChangeService events
        if (m_changeService != null) {
            m_changeService.add_ComponentChanged(new 
                ComponentChangedEventHandler(OnComponentChanged));
            m_changeService.add_ComponentChanging(new 
                ComponentChangingEventHandler(OnComponentChanging));
            m_changeService.add_ComponentAdded(new 
                ComponentEventHandler(OnComponentAdded));
            m_changeService.add_ComponentAdding(new 
                ComponentEventHandler(OnComponentAdding));
            m_changeService.add_ComponentRemoved(new 
                ComponentEventHandler(OnComponentRemoved));
            m_changeService.add_ComponentRemoving(new 
                ComponentEventHandler(OnComponentRemoving));
            m_changeService.add_ComponentRename(new 
                ComponentRenameEventHandler(OnComponentRename));
        }
    } //RegisterChangeNotifications

    /* This method handles the OnComponentChanged event to 
        // display a notification. 
     */

    private void OnComponentChanged(Object sender, ComponentChangedEventArgs ce)
    {
        if (ce.get_Component() != null && 
            ((IComponent)ce.get_Component()).get_Site() != null &&
            ce.get_Member() != null) {
            OnUserChange("The " + ce.get_Member().get_Name() 
                + " member of the " 
                + ((IComponent)ce.get_Component()).get_Site().get_Name() 
                + " component has been changed.");
        }
    } //OnComponentChanged

    /* This method handles the OnComponentChanging event to
        display a notification. 
     */
    private void OnComponentChanging(Object sender,
        ComponentChangingEventArgs ce)
    {
        if (ce.get_Component() != null && 
            ((IComponent)ce.get_Component()).get_Site() != null && 
            ce.get_Member() != null) {
            OnUserChange(("The " + ce.get_Member().get_Name() 
                + " member of the " 
                + ((IComponent)ce.get_Component()).get_Site().get_Name() 
                + " component is being changed."));
        }
    } //OnComponentChanging

    /* This method handles the OnComponentAdded event 
        to display a notification.
     */
    private void OnComponentAdded(Object sender, ComponentEventArgs ce)
    {
        OnUserChange("A component, " + ce.get_Component().get_Site().get_Name()
            + ", has been added.");
    } //OnComponentAdded

    /* This method handles the OnComponentAdding event 
        to display a notification. 
     */
    private void OnComponentAdding(Object sender, ComponentEventArgs ce)
    {
        OnUserChange("A component of type " 
            + ce.get_Component().GetType().get_FullName() 
            + " is being added.");
    } //OnComponentAdding

    /* This method handles the OnComponentRemoved event 
        to display a notification. 
     */
    private void OnComponentRemoved(Object sender, ComponentEventArgs ce)
    {
        OnUserChange("A component, " + ce.get_Component().get_Site().get_Name()
            + ", has been removed.");
    } //OnComponentRemoved

    /* This method handles the OnComponentRemoving event 
        to display a notification. 
     */
    private void OnComponentRemoving(Object sender, ComponentEventArgs ce)
    {
        OnUserChange("A component, " + ce.get_Component().get_Site().get_Name()
            + ", is being removed.");
    } //OnComponentRemoving

    /* This method handles the OnComponentRename event
        to display a notification.
     */
    private void OnComponentRename(Object sender, ComponentRenameEventArgs ce)
    {
        OnUserChange("A component, " + ce.get_OldName() + ", was renamed to " 
            + ce.get_NewName() + ".");
    } //OnComponentRename

    // This method adds a specified notification message
    // to the control's listbox.
    private void OnUserChange(String text)
    {
        listBox1.get_Items().Add(text);
    } //OnUserChange

    // Clean up any resources being used.
    protected void Dispose(boolean disposing)
    {
        if (disposing) {
            ClearChangeNotifications();
            if (components != null) {
                components.Dispose();
            }
        }
        super.Dispose(disposing);
    } //Dispose
} //ComponentClass

Windows 98, Windows Server 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

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