.NET Framework Class Library
ControlDesignerGetEmptyDesignTimeHtml Method

Retrieves the HTML markup to represent a Web server control at design time that will have no visual representation at run time.

Namespace:   System.Web.UI.Design
Assembly:  System.Design (in System.Design.dll)
Syntax
Protected Overridable Function GetEmptyDesignTimeHtml As [%$TOPIC/ddyct9bh_en-us_VS_110_1_0_0_0_0%]
protected virtual [%$TOPIC/ddyct9bh_en-us_VS_110_1_0_1_0_0%] GetEmptyDesignTimeHtml()
protected:
virtual [%$TOPIC/ddyct9bh_en-us_VS_110_1_0_2_0_0%]^ GetEmptyDesignTimeHtml()
abstract GetEmptyDesignTimeHtml : unit -> [%$TOPIC/ddyct9bh_en-us_VS_110_1_0_3_0_0%]  
override GetEmptyDesignTimeHtml : unit -> [%$TOPIC/ddyct9bh_en-us_VS_110_1_0_3_0_1%]
protected function GetEmptyDesignTimeHtml() : [%$TOPIC/ddyct9bh_en-us_VS_110_1_0_4_0_0%]

Return Value

Type: SystemString
The HTML markup used to represent a control at design time that would otherwise have no visual representation. The default is a rectangle that contains the type and ID of the component.
Remarks

The default behavior of the GetEmptyDesignTimeHtml method is to return a string that contains the name of the component. The GetEmptyDesignTimeHtml method should be called in the implementation of the GetDesignTimeHtml method when there is no design-time HTML markup.

Examples

The following code example demonstrates how to override the GetDesignTimeHtml method in a custom control designer. If the Text property for the associated control is empty, the GetDesignTimeHtml method calls GetEmptyDesignTimeHtml method. Otherwise, the GetDesignTimeHtml method creates and renders a Hyperlink control.

Public Overrides Function GetDesignTimeHtml() As String 
   ' Component is the instance of the component or control that 
   ' this designer object is associated with. This property is  
   ' inherited from System.ComponentModel.ComponentDesigner.
   simpleControl = CType(Component, Simple)

   If simpleControl.Text.Length > 0 Then 
      Dim sw As New StringWriter()
      Dim tw As New HtmlTextWriter(sw)

      Dim placeholderLink As New HyperLink()

      ' Put simpleControl.Text into the link's Text.
      placeholderLink.Text = simpleControl.Text
      placeholderLink.NavigateUrl = simpleControl.Text
      placeholderLink.RenderControl(tw)

      Return sw.ToString()
   Else 
      Return GetEmptyDesignTimeHtml()
   End If 
End Function
public override string GetDesignTimeHtml()
{
    if (simpleControl.Text.Length > 0)
    {
        string spec = "<a href='{0}.aspx'>{0}</a>";
        return String.Format(spec, simpleControl.Text);
    }
    else 
        return GetEmptyDesignTimeHtml();
}
Version Information

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1