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HtmlTextWriter.IsStyleAttributeDefined Method (HtmlTextWriterStyle)

Determines whether the specified markup style attribute is rendered during the next call to the RenderBeginTag method.

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

protected bool IsStyleAttributeDefined(
	HtmlTextWriterStyle key


Type: System.Web.UI.HtmlTextWriterStyle
The HtmlTextWriterStyle associated with the attribute.

Return Value

Type: System.Boolean
true if the attribute will be rendered during the next call to the RenderBeginTag method; otherwise, false.

To get the value that will be rendered with the specified style attribute, use the IsStyleAttributeDefined(HtmlTextWriterStyle, String) overload of the IsStyleAttributeDefined method.

The following code example shows how to check whether a <label> element is being rendered. If so, the IsStyleAttributeDefined method checks whether a Color style attribute has been defined on the element. If the Color attribute has not been defined, the AddStyleAttribute method defines the Color attribute and sets its value to red.

// If the markup element being rendered is a Label,
// render the opening tag of a Font element before it.
if (tagKey == HtmlTextWriterTag.Label)
    // Check whether a Color style attribute is 
    // included on the Label. If not, use the
    // AddStyleAttribute and GetStyleName methods to add one
    // and set its value to red.
    if (!IsStyleAttributeDefined(HtmlTextWriterStyle.Color))
        AddStyleAttribute(GetStyleName(HtmlTextWriterStyle.Color), "red");

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

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

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