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IsStyleAttributeDefined Method (HtmlTextWriterStyle)

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: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1
© 2015 Microsoft