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.

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();
}

.NET Framework

• Full trust for the immediate caller. This member cannot be used by partially trusted code. For more information, see Using Libraries from Partially Trusted Code.

Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Reference

Other Resources