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HiddenFieldDesigner Class

Note: This class is new in the .NET Framework version 2.0.

Provides design-time support in a visual designer for the HiddenField control.

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

public class HiddenFieldDesigner : ControlDesigner
public class HiddenFieldDesigner extends ControlDesigner
public class HiddenFieldDesigner extends ControlDesigner

In a visual designer, when the user switches from Source to Design view, the markup source code that describes a HiddenField control is parsed and a design-time version of the control is created on the design surface. When the user switches back to Source view, the design-time control is persisted to the markup source code and edited into the markup for the Web page. The HiddenFieldDesigner class provides design-time support for the HiddenField in a visual designer.

The GetDesignTimeHtml method returns the markup that is used to render the associated HiddenField at design time. The Initialize method prepares the designer to view, edit, and design the associated HiddenField.

The following code example shows how to extend the HiddenFieldDesigner class to change the appearance of controls that are derived from the HiddenField control at design time.

The example derives the MyHiddenField control from the HiddenField. The MyHiddenField is a copy of the HiddenField. The example also derives the MyHiddenFieldDesigner class from the HiddenFieldDesigner class and applies a DesignerAttribute attribute for the MyHiddenFieldDesigner on the MyHiddenField control.

The MyHiddenFieldDesigner overrides the GetDesignTimeHtml method to generate a placeholder that includes the Value property in the placeholder, along with the control class name and the ID property.

using System;
using System.Web;
using System.Web.UI.WebControls;
using System.Web.UI.Design.WebControls;
using System.ComponentModel;
using System.Security.Permissions;

namespace Examples.CS.WebControls.Design
{
    // The MyHiddenField is a copy of the HiddenField.
    [AspNetHostingPermission(SecurityAction.Demand, 
        Level = AspNetHostingPermissionLevel.Minimal)]
    [AspNetHostingPermission(SecurityAction.InheritanceDemand, 
        Level = AspNetHostingPermissionLevel.Minimal)]
    [Designer(typeof(Examples.CS.WebControls.Design.MyHiddenFieldDesigner))]
    public class MyHiddenField : HiddenField
    {
    } // MyHiddenField

    // Derive a designer that inherits from the HiddenFieldDesigner.
    public class MyHiddenFieldDesigner : HiddenFieldDesigner
    {
        // Generate the design-time markup.
        public override string GetDesignTimeHtml()
        {
            // Get a reference to the control or a copy of the control.
            MyHiddenField myHF = (MyHiddenField)ViewControl;

            // Create a placeholder that displays the control value.
            string markup = CreatePlaceHolderDesignTimeHtml(
                 "Value: \"" + myHF.Value.ToString() + "\"" );

            return markup;

        } // GetDesignTimeHtml
    } // MyHiddenFieldDesigner
} // Examples.CS.WebControls.Design

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 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

.NET Framework

Supported in: 2.0
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