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DataGridDesigner Class

Extends design-time behavior for the DataGrid Web server control.

Namespace: System.Web.UI.Design.WebControls
Assembly: System.Design (in system.design.dll)

public ref class DataGridDesigner : public BaseDataListDesigner
public class DataGridDesigner extends BaseDataListDesigner
public class DataGridDesigner extends BaseDataListDesigner
Not applicable.

The following code example demonstrates how to extend the DataGridDesigner class. The code overrides the GetDesignTimeHtml method to customize the CellPadding, BorderWidth, and BorderColor properties when the DataGrid control is rendered on a design surface.

Imports System
Imports System.Diagnostics
Imports System.ComponentModel
Imports System.Drawing
Imports System.Web.UI.Design.WebControls
Imports System.Web.UI.WebControls

Namespace Examples.AspNet

    ' Create a designer class for the SimpleDataList class.
    <System.Security.Permissions.SecurityPermission( _
    System.Security.Permissions.SecurityAction.Demand, _
    Flags:=System.Security.Permissions.SecurityPermissionFlag.UnmanagedCode)> _
    Public Class SimpleDataListDesigner
        Inherits DataListDesigner

        Private simpleList As SimpleDataList


        ' Override the GetDesignTimeHtml method to add style to the control
        ' on the design surface.
        Public Overrides Function GetDesignTimeHtml() As String
            ' Cast the control to the Component property of the designer.
            simpleList = CType(Component, SimpleDataList)

            Dim designTimeHtml As String = Nothing

            ' Create variables to hold current property values.
            Dim oldBorderWidth As Unit = simpleList.BorderWidth
            Dim oldBorderColor As Color = simpleList.BorderColor

            ' Set the properties and generate the design-time HTML.
            If (simpleList.Enabled) Then
                Try
                    simpleList.BorderWidth = Unit.Point(5)
                    simpleList.BorderColor = Color.Purple
                    designTimeHtml = MyBase.GetDesignTimeHtml()

                    ' Call the GetErrorDesignTimeHtml method if an
                    ' exception occurs.
                Catch ex As Exception
                    designTimeHtml = GetErrorDesignTimeHtml(ex)

                    ' Return the properties to their original settings.
                Finally
                    simpleList.BorderWidth = oldBorderWidth
                    simpleList.BorderColor = oldBorderColor
                End Try
                ' If the list is not enabled, call the GetEmptyDesignTimeHtml
                ' method.
            Else
                designTimeHtml = GetEmptyDesignTimeHtml()
            End If

            Return designTimeHtml

        End Function

        Protected Overrides Function GetEmptyDesignTimeHtml() As String
            Dim emptyText As String

            ' Check the CanEnterTemplateMode property to
            ' specify which text to display if ItemTemplate 
            ' does not contain a value.
            If CanEnterTemplateMode Then
                emptyText = _
                    "<b>Either the Enabled property value is false " + _
                    "or you need to set the ItemTemplate for this " + _
                    "control.<br>Right-click to edit templates.</b>"
            Else
                emptyText = _
                    "<b>You cannot edit templates in this view.<br>" + _
                    "Switch to HTML view to define the ItemTemplate.</b>"
            End If

            Return CreatePlaceHolderDesignTimeHtml(emptyText)
        End Function

        ' Generate HTML to indicate that an error has occurred.
        Protected Overrides Function GetErrorDesignTimeHtml(ByVal exc As _
            Exception) As String

            Return CreatePlaceHolderDesignTimeHtml( _
                "<b>An error occurred</b>.<br>Check to ensure that all " + _
                "properties are valid.")
        End Function


        ' Override the Initialize method to ensure that
        ' only an instance of the SimpleDataList class is
        ' used by this designer class.
        Public Overrides Sub Initialize(ByVal component As IComponent)
            simpleList = CType(component, SimpleDataList)

            If IsNothing(simpleList) Then
                Throw New ArgumentException("Must be a SimpleDataList.", "component")
            End If

            MyBase.Initialize(component)
        End Sub
    End Class
End Namespace

The following example shows how to use the DesignerAttribute attribute to associate the designer with the DataGrid control.

' Override the Initialize method to ensure that
' only an instance of the SimpleDataList class is
' used by this designer class.
Public Overrides Sub Initialize(ByVal component As IComponent)
    simpleList = CType(component, SimpleDataList)

    If IsNothing(simpleList) Then
        Throw New ArgumentException("Must be a SimpleDataList.", "component")
    End If

    MyBase.Initialize(component)
End Sub

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 98, Windows Server 2000 SP4, 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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