HtmlTextWriter.OnTagRender Method (System.Web.UI)

OnTagRender Method

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This page is specific to

Microsoft Visual Studio 2008/.NET Framework 3.5

Other versions are also available for the following:

.NET Framework Class Library

HtmlTextWriter..::.OnTagRender Method

Updated: November 2007

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

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

Syntax

Visual Basic (Declaration)

Protected Overridable Function OnTagRender ( _
    name As String, _
    key As HtmlTextWriterTag _
) As Boolean

Visual Basic (Usage)

Dim name As String
Dim key As HtmlTextWriterTag
Dim returnValue As Boolean

returnValue = Me.OnTagRender(name, _
    key)

protected virtual bool OnTagRender(
    string name,
    HtmlTextWriterTag key
)

Visual C++

protected:
virtual bool OnTagRender(
    String^ name, 
    HtmlTextWriterTag key
)

protected boolean OnTagRender(
    String name,
    HtmlTextWriterTag key
)

JScript

protected function OnTagRender(
    name : String, 
    key : HtmlTextWriterTag
) : boolean

Parameters

name: Type: System..::.String
A string containing the name of the element to render.

key: Type: System.Web.UI..::.HtmlTextWriterTag
The HtmlTextWriterTag associated with the element.

Return Value

Type: System..::.Boolean

Always true.

Remarks

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.

Examples

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.

Visual Basic

' 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 Overrides Function OnTagRender( _
    name As String, _
    key As HtmlTextWriterTag) _
As Boolean

    If (key = HtmlTextWriterTag.Font) Then
        If Not (IsAttributeDefined(HtmlTextWriterAttribute.Size)) Then
            AddAttribute(HtmlTextWriterAttribute.Size, "20pt")
            Return True
        End If
    End If

    ' If the element is not a <font> element, use
    ' the base functionality of the OnTagRenderMethod.
    Return MyBase.OnTagRender(name, key)
End Function

// 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);
}

Platforms

Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, 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.

Version Information