ToolboxDataAttribute Class

By default, the visual designer of a tool such as Visual Studio, creates an empty tag. This is a tag representing a control in its default state, when the control is dropped from the toolbox of a visual designer onto the design surface. To specify initial default values, a control can make use of this attribute. You can use this attribute to customize the initial HTML content that is placed in the designer when the control is dragged from the toolbox onto the form.

[ ToolboxData("<{0}:MyLabel runat= server Text= 
       MyLabel><{0}:MyLabel>") ]public class MyLabel : Label {...}

In the following code example, the previous code sets several properties specific to MyLabel. All occurrences of {0} are replaced, by the designer, with the tag prefix associated with the MyLabel class.

using System;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;


namespace CustomControls
{

  [ ToolboxData("<{0}:MyLabel Text='MyLabel' BorderColor='Yellow' BackColor='Magenta' BorderWidth = '10'  runat='server'></{0}:MyLabel>") ]	
  public class MyLabel : Label 
  {
    public  MyLabel()
    { 
      // Your code goes here.
    } 
  }

}

.NET Framework

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

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