IRootDesigner Interface


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Provides support for root-level designer view technologies.

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

public interface IRootDesigner : IDesigner, IDisposable


Gets the base component that this designer is designing.(Inherited from IDesigner.)


Gets the set of technologies that this designer can support for its display.


Gets a collection of the design-time verbs supported by the designer.(Inherited from IDesigner.)


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


Performs the default action for this designer.(Inherited from IDesigner.)


Gets a view object for the specified view technology.


Initializes the designer with the specified component.(Inherited from IDesigner.)

A root designer is the designer that is in the top position, or root, of the current design-time document object hierarchy. A root designer must implement the IRootDesigner interface. A root designer typically manages the background view in designer view mode, and usually displays the controls within the base container of the current design time project.

The following code example demonstrates a IRootDesigner implementation associated with a sample user control. This IRootDesigner implementation displays a control for the background view in designer view by overriding the GetView method. You need to add a reference to the System.Design assembly to compile the example.

To use this example, add the source code to a project and show the RootViewSampleComponent in designer view to display the custom root designer view.

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

namespace SampleRootDesigner
    // This sample demonstrates how to provide the root designer view, or
    // design mode background view, by overriding IRootDesigner.GetView().

    // This sample component inherits from RootDesignedComponent which 
    // uses the SampleRootDesigner.
    public class RootViewSampleComponent : RootDesignedComponent
        public RootViewSampleComponent()

    // The following attribute associates the SampleRootDesigner designer 
    // with the SampleComponent component.
    [Designer(typeof(SampleRootDesigner), typeof(IRootDesigner))]
    public class RootDesignedComponent : Component
        public RootDesignedComponent()

    public class SampleRootDesigner : ComponentDesigner, IRootDesigner
        // Member field of custom type RootDesignerView, a control that 
        // will be shown in the Forms designer view. This member is 
        // cached to reduce processing needed to recreate the 
        // view control on each call to GetView().
        private RootDesignerView m_view;			

        // This method returns an instance of the view for this root
        // designer. The "view" is the user interface that is presented
        // in a document window for the user to manipulate. 
        object IRootDesigner.GetView(ViewTechnology technology) 
            if (technology != ViewTechnology.Default)
                throw new ArgumentException("Not a supported view technology", "technology");
            if (m_view == null)
                   // Some type of displayable Form or control is required 
                   // for a root designer that overrides GetView(). In this 
                   // example, a Control of type RootDesignerView is used.
                   // Any class that inherits from Control will work.
                m_view = new RootDesignerView(this);
            return m_view;

        // IRootDesigner.SupportedTechnologies is a required override for an
        // IRootDesigner. Default is the view technology used by this designer.  
        ViewTechnology[] IRootDesigner.SupportedTechnologies 
                return new ViewTechnology[] {ViewTechnology.Default};

        // RootDesignerView is a simple control that will be displayed 
        // in the designer window.
        private class RootDesignerView : Control 
            private SampleRootDesigner m_designer;

            public RootDesignerView(SampleRootDesigner designer)
                m_designer = designer;
                BackColor = Color.Blue;
                Font = new Font(Font.FontFamily.Name, 24.0f);

            protected override void OnPaint(PaintEventArgs pe)

                // Draws the name of the component in large letters.
                pe.Graphics.DrawString(m_designer.Component.Site.Name, Font, Brushes.Yellow, ClientRectangle);

.NET Framework
Available since 1.1
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