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HtmlTextWriter.OnTagRender Method

Determines whether the specified markup element will be rendered to the requesting page.

Namespace:  System.Web.UI
Assembly:  System.Web (in System.Web.dll)

protected virtual bool OnTagRender(
	string name,
	HtmlTextWriterTag key


Type: System.String

A string containing the name of the element to render.

Type: System.Web.UI.HtmlTextWriterTag

The HtmlTextWriterTag associated with the element.

Return Value

Type: System.Boolean
Always true.

The HtmlTextWriter class implementation of the OnTagRender method always returns true. The OnTagRender overrides can determine whether an element will be rendered to the page.

Notes to Inheritors:

If you inherit from the HtmlTextWriter class, you can override the OnTagRender method to return false to prevent a markup element from being rendered at all or for a particular markup language. For example, if you do not want the object that is derived from HtmlTextWriter to render the <font> element, you can override the OnTagRender method to return false when a page is requested that contains a <font> element.

The following code example shows how to override the OnTagRender method. If a Font element is being rendered, the OnTagRender override uses the IsAttributeDefined method to determine whether a Size attribute is being rendered. If not, it uses the AddAttribute method to create a Size attribute and set its value to 20pt.

// If a <font> element is to be rendered, check whether it contains 
// a size attribute. If it does not, add one and set its value to 
// 20 points, then return true. 
protected override bool OnTagRender(string name, HtmlTextWriterTag key)

    if (key == HtmlTextWriterTag.Font)
        if (!(IsAttributeDefined(HtmlTextWriterAttribute.Size)))
            AddAttribute(HtmlTextWriterAttribute.Size, "20pt");
            return true;

    // If the element is not a <font> element, use 
    // the base functionality of the OnTagRenderMethod. 
    return base.OnTagRender(name, key);

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

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

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0