Notifies an System.Web.UI.HtmlTextWriter object, or an object of a derived class, that a control is about to be rendered.
The System.Web.UI.HtmlTextWriter class implementation of the HtmlTextWriter.BeginRender method has no functionality. You must override the HtmlTextWriter.BeginRender method in a class derived from System.Web.UI.HtmlTextWriter to provide your own rendering functionality. For example, in a markup language that might require <p> elements to be rendered immediately ahead of a control, but where the need for the <p> element is determined earlier, you could use the HtmlTextWriter.BeginRender override.