IDesigner Interface


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Provides the basic framework for building a custom designer.

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

public interface IDesigner : IDisposable


Gets the base component that this designer is designing.


Gets a collection of the design-time verbs supported by the designer.


Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.(Inherited from IDisposable.)


Performs the default action for this designer.


Initializes the designer with the specified component.

The IDesigner interface provides an interface through which you can implement basic services for a designer. A designer can modify the behavior of a component at design time, and may provide its own services and behavior. A designer is only active at design-time, and must be associated with a type of component using a DesignerAttribute in order to be loaded when a component of the associated type is created at design time.

The IDesigner interface provides methods and properties that you can implement in order to provide custom behavior at design time.

Implement the Initialize method of a designer to perform actions when a component is created. This can be useful if a component should have a special configuration at design-time, or if its configuration should change depending on conditions that the designer can determine.

A designer can provide menu commands on the shortcut menu that is displayed when a user right-clicks a component or control in the design-time environment. You can implement the Verbs property to define a get accessor that returns a DesignerVerbCollection containing the DesignerVerb objects for generating menu commands.

A designer for a component that appears in the component tray can perform a default action when the component is double-clicked. Implement the DoDefaultAction method to specify the behavior to perform when the component is double-clicked.

A designer can also use the available design-time services to perform a variety of tasks, including surveying the current design-time environment for components and their properties, reading and setting the values of properties of components, managing the toolbox, managing selected components, or displaying a user interface that can be used to configure values or to apply further processing.

To implement a designer for a control that can be sited on a form, you can inherit from the ControlDesigner class. Controls whose associated designer does not derive from ControlDesigner are displayed in the component tray. The ComponentDesigner and ControlDesigner classes implement the IDesigner interface and provide additional design-time support that may be of use to authors of designers. For more information, see the reference documentation for these classes.

For an overview of creating design components, please see Extending Design-Time Support.

This example demonstrates an IDesigner implementation that stores a local reference to its component, performs a default action when the component is double-clicked, and provides a designer verb menu command.

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

namespace IDesignerExample
    // A DesignerAttribute associates the example IDesigner with an example control.
    public class TestControl : System.Windows.Forms.UserControl
        public TestControl()

    [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")] 
    public class ExampleIDesigner : System.ComponentModel.Design.IDesigner
        // Local reference to the designer's component.
        private IComponent component; 
        // Public accessor to the designer's component.
        public System.ComponentModel.IComponent Component
                return component;

        public ExampleIDesigner()

        public void Initialize(System.ComponentModel.IComponent component)
            // This method is called after a designer for a component is created,
            // and stores a reference to the designer's component.
            this.component = component;

        // This method peforms the 'default' action for the designer. The default action 
        // for a basic IDesigner implementation is invoked when the designer's component 
        // is double-clicked. By default, a component associated with a basic IDesigner 
        // implementation is displayed in the design-mode component tray.
        public void DoDefaultAction()
            // Shows a message box indicating that the default action for the designer was invoked.
            MessageBox.Show("The DoDefaultAction method of an IDesigner implementation was invoked.", "Information");

        // Returns a collection of designer verb menu items to show in the 
        // shortcut menu for the designer's component.
        public System.ComponentModel.Design.DesignerVerbCollection Verbs
                DesignerVerbCollection verbs = new DesignerVerbCollection();
                DesignerVerb dv1 = new DesignerVerb("Display Component Name", new EventHandler(this.ShowComponentName));
                verbs.Add( dv1 );
                return verbs;

        // Event handler for displaying a message box showing the designer's component's name.
        private void ShowComponentName(object sender, EventArgs e)
            if( this.Component != null )
                MessageBox.Show( this.Component.Site.Name, "Designer Component's Name" );

        // Provides an opportunity to release resources before object destruction.
        public void Dispose()

.NET Framework
Available since 1.1
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