HtmlTextWriter::IsAttributeDefined Method (HtmlTextWriterAttribute)
Determines whether the specified markup attribute and its value are rendered during the next call to the RenderBeginTag method.
Assembly: System.Web (in System.Web.dll)
Parameters
- key
-
Type:
System.Web.UI::HtmlTextWriterAttribute
The HtmlTextWriterAttribute associated with the markup attribute.
Return Value
Type: System::Booleantrue if the attribute is rendered during the next call to the RenderBeginTag method; otherwise, false.
To obtain the value to be assigned to the HtmlTextWriterAttribute object, use the IsAttributeDefined(HtmlTextWriterAttribute, String^%) overload instead of this one.
The following code example shows how to use an override of the RenderBeginTag method in a class that inherits from the HtmlTextWriter class. The RenderBeginTag override checks whether a <font> markup element will be rendered. If so, the override calls the IsAttributeDefined method to check whether the <font> element contains a Size attribute. If not, the AddAttribute method calls the GetAttributeKey method, which defines the Size attribute and sets its value to 30pt.
// If the tagKey parameter is set to a <font> element // but a size attribute is not defined on the element, // the AddStyleAttribute method adds a size attribute // and sets it to 30 point. if ( tagKey == HtmlTextWriterTag::Font ) { if ( !IsAttributeDefined( HtmlTextWriterAttribute::Size ) ) { AddAttribute( GetAttributeKey( "size" ), "30pt" ); } }
Available since 1.1