IRootDesigner Interface


Provides support for root-level designer view technologies.

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

Public Interface IRootDesigner
	Inherits 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.

Imports System
Imports System.Collections
Imports System.ComponentModel
Imports System.ComponentModel.Design
Imports System.Diagnostics
Imports System.Drawing
Imports System.Windows.Forms
Imports 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
        Inherits RootDesignedComponent

        Public Sub New()
        End Sub

    End Class

    ' The following attribute associates the SampleRootDesigner designer 
    ' with the SampleComponent component.
    <Designer(GetType(SampleRootDesigner), GetType(IRootDesigner))> _
    Public Class RootDesignedComponent
        Inherits Component

        Public Sub New()
        End Sub 

    End Class 

    Public Class SampleRootDesigner
        Inherits ComponentDesigner
        Implements 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 m_view As RootDesignerView

        ' 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. 
        Function GetView(ByVal technology As ViewTechnology) As Object Implements IRootDesigner.GetView
            If Not technology = ViewTechnology.Default Then
                Throw New ArgumentException("Not a supported view technology", "technology")
            End If
            If m_view Is Nothing Then
                ' 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(Me)
            End If
            Return m_view
        End Function 

        ' IRootDesigner.SupportedTechnologies is a required override for an 
        ' IRootDesigner. Default is the view technology used by this designer.
        ReadOnly Property SupportedTechnologies() As ViewTechnology() Implements IRootDesigner.SupportedTechnologies
                Return New ViewTechnology() {ViewTechnology.Default}
            End Get
        End Property

        ' RootDesignerView is a simple control that will be displayed 
        ' in the designer window.
        Private Class RootDesignerView
            Inherits Control
            Private m_designer As SampleRootDesigner

            Public Sub New(ByVal designer As SampleRootDesigner)
                m_designer = designer
                BackColor = Color.Blue
                Font = New Font(Font.FontFamily.Name, 24.0F)
            End Sub 

            Protected Overrides Sub OnPaint(ByVal pe As PaintEventArgs)
                ' Draws the name of the component in large letters.
                Dim rf As New RectangleF(ClientRectangle.X, ClientRectangle.Y, ClientRectangle.Width, ClientRectangle.Height)
                pe.Graphics.DrawString(m_designer.Component.Site.Name, Font, Brushes.Yellow, rf)
            End Sub 

        End Class
    End Class

End Namespace 

.NET Framework
Available since 1.1
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