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IDesignerHost Interface

Provides an interface for managing designer transactions and components.

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

public interface IDesignerHost : IServiceContainer, 

IDesignerHost is an interface that works with the .NET Framework forms designer architecture to provide support for designer transaction and component management.

The .NET Framework does not provide an implementation of this interface. The interface is implemented by development tools that support designers.

Notes to Callers:

To obtain an implementation of IDesignerHost from a development environment, call GetService while your component is active in design mode, passing the type of IDesignerHost to request an IDesignerHost service interface.

IDesignerHost provides the following members related to designer state:

  • The Loading property indicates whether a designer or document is being loaded.

  • The Activated event occurs when a designer is activated before display.

  • The Deactivated event occurs when a designer is deactivated.

  • The LoadComplete event occurs after a document is loaded.

  • The Activate method activates the designer.

IDesignerHost provides the following members related to managing components:

  • The Container property indicates the container for the designer host.

  • The RootComponent property indicates the base class for the root component.

  • The RootComponentClassName property indicates the name of the class of the root component.

  • The CreateComponent method creates the specified type of component.

  • The DestroyComponent method destroys the specified component.

  • The GetDesigner method gets the designer associated with a specified component.

  • The GetType method gets an instance of the type with the specified name.

IDesignerHost provides the following members related to managing transactions:

The following example code demonstrates how to obtain the IDesignerHost service interface from a designer or sited component.

			// Requests an IDesignerHost service from the design time environment using Component.Site.GetService()
			IDesignerHost dh = (IDesignerHost) this.Component.Site.GetService(typeof(IDesignerHost));			

The following example code demonstrates using the IDesignerHost interface to list project components.

using System;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Drawing;
using System.Windows.Forms;

namespace IDesignerHostExample
    // IDesignerHostExampleComponent is a component associated  
    // with the IDesignerHostExampleDesigner that demonstrates  
    // acquisition and use of the IDesignerHost service  
    // to list project components.
    public class IDesignerHostExampleComponent : System.ComponentModel.Component
        public IDesignerHostExampleComponent()

        protected override void Dispose( bool disposing )
            base.Dispose( disposing );

    // You can double-click the component of an IDesignerHostExampleDesigner  
    // to show a form containing a listbox that lists the name and type  
    // of each component or control in the current design-time project.
    [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")] 
    public class IDesignerHostExampleDesigner : IDesigner
        private System.ComponentModel.IComponent component;

        public IDesignerHostExampleDesigner()

        public void DoDefaultAction()

        public void Initialize(System.ComponentModel.IComponent component)
            this.component = component;
            MessageBox.Show("Double-click the IDesignerHostExample component to view a list of project components.");

        // Displays a list of components in the current design  
        // document when the default action of the designer is invoked. 
        private void ListComponents()
            using (DesignerHostListForm listform = new DesignerHostListForm())
                // Obtain an IDesignerHost service from the design environment.
                IDesignerHost host = (IDesignerHost)this.component.Site.GetService(typeof(IDesignerHost));
                // Get the project components container (control containment depends on Controls collections)
                IContainer container = host.Container;
                // Add each component's type name and name to the list box. 
                foreach (IComponent component in container.Components)
                    listform.listBox1.Items.Add(component.GetType().Name + " : " + component.Site.Name);
                // Display the form.

        public System.ComponentModel.IComponent Component
                return this.component;

        public System.ComponentModel.Design.DesignerVerbCollection Verbs
                DesignerVerbCollection dvc = new DesignerVerbCollection();
                dvc.Add( new DesignerVerb("List Components", new EventHandler(ListHandler)) );
                return dvc;

        private void ListHandler(object sender, EventArgs e)

        public void Dispose() {	}

    // Provides a form containing a listbox that can display  
    // a list of project components. 
    public class DesignerHostListForm : System.Windows.Forms.Form
        public System.Windows.Forms.ListBox listBox1;
        private System.Windows.Forms.Button ok_button;

        public DesignerHostListForm()
            this.Name = "DesignerHostListForm";
            this.Text = "List of design-time project components";
            this.listBox1 = new System.Windows.Forms.ListBox();						
            this.listBox1.Location = new System.Drawing.Point(8, 8);
            this.listBox1.Name = "listBox1";
            this.listBox1.Size = new System.Drawing.Size(385, 238);
            this.listBox1.TabIndex = 0;	
            this.listBox1.Anchor = (((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Bottom) 
                | System.Windows.Forms.AnchorStyles.Left) 
                | System.Windows.Forms.AnchorStyles.Right);		
            this.ok_button = new System.Windows.Forms.Button();
            this.ok_button.DialogResult = System.Windows.Forms.DialogResult.OK;
            this.ok_button.Location = new System.Drawing.Point(232, 256);
            this.ok_button.Name = "ok_button";
            this.ok_button.TabIndex = 1;
            this.ok_button.Text = "OK";
            this.ok_button.Anchor = (System.Windows.Forms.AnchorStyles.Bottom | System.Windows.Forms.AnchorStyles.Right);
            this.ClientSize = new System.Drawing.Size(400, 285);
            this.Controls.AddRange(new System.Windows.Forms.Control[] { this.ok_button, this.listBox1 });

        protected override void Dispose( bool disposing )
            base.Dispose( disposing );

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

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

.NET Framework

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