ÿþ/**

 * @projectDescription Monitor Font Size Changes with jQuery

 *

 * @version 1.0

 * @author Dave Cardwell

 *

 * jQuery-Em - $Revision: 24 $ ($Date: 2007-08-19 11:24:56 +0100 (Sun, 19 Aug 2007) $)

 * http://davecardwell.co.uk/javascript/jquery/plugins/jquery-em/

 *

 * Copyright ©2007 Dave Cardwell <http://davecardwell.co.uk/>

 *

 * Released under the MIT licence:

 * http://www.opensource.org/licenses/mit-license.php

 */



// Upon $(document).ready()& 

jQuery(function($) {

    // Configuration& 

    var eventName = 'emchange';

    

    

    // Set up default options.

    $.em = $.extend({

        /**

         * The jQuery-Em version string.

         *

         * @example $.em.version;

         * @desc '1.0a'

         *

         * @property

         * @name version

         * @type String

         * @cat Plugins/Em

         */

        version: '1.0',

        

        /**

         * The number of milliseconds to wait when polling for changes to the

         * font size.

         *

         * @example $.em.delay = 400;

         * @desc Defaults to 200.

         *

         * @property

         * @name delay

         * @type Number

         * @cat Plugins/Em

         */

        delay: 200,

        

        /**

         * The element used to detect changes to the font size.

         *

         * @example $.em.element = $('<div />')[0];

         * @desc Default is an empty, absolutely positioned, 100em-wide <div>.

         *

         * @private

         * @property

         * @name element

         * @type Element

         * @cat Plugins/Em

         */

        element: $('<div />').css({ left:     '-100em',

                                    position: 'absolute',

                                    width:    '100em' })

                             .prependTo('body')[0],

        

        /**

         * The action to perform when a change in the font size is detected.

         *

         * @example $.em.action = function() { ... }

         * @desc The default action is to trigger a global  emchange  event.

         * You probably shouldn t change this behaviour as other plugins may

         * rely on it, but the option is here for completion.

         *

         * @example $(document).bind('emchange', function(e, cur, prev) {...})

         * @desc Any functions triggered on this event are passed the current

         * font size, and last known font size as additional parameters.

         *

         * @private

         * @property

         * @name action

         * @type Function

         * @cat Plugins/Em

         * @see current

         * @see previous

         */

        action: function() {

            var currentWidth = $.em.element.offsetWidth / 100;

            

            // If the font size has changed since we last checked& 

            if ( currentWidth != $.em.current ) {

                /**

                 * The previous pixel value of the user agent s font size. See

                 * $.em.current for caveats. Will initially be undefined until

                 * the  emchange  event is triggered.

                 *

                 * @example $.em.previous;

                 * @result 16

                 *

                 * @property

                 * @name previous

                 * @type Number

                 * @cat Plugins/Em

                 * @see current

                 */

                $.em.previous = $.em.current;

                

                /**

                 * The current pixel value of the user agent s font size. As

                 * with $.em.previous, this value *may* be subject to minor

                 * browser rounding errors that mean you might not want to

                 * rely upon it as an absolute value.

                 *

                 * @example $.em.current;

                 * @result 14

                 *

                 * @property

                 * @name current

                 * @type Number

                 * @cat Plugins/Em

                 * @see previous

                 */

                $.em.current = currentWidth;

                

                $.event.trigger(eventName, [$.em.current, $.em.previous]);

            }

        }

    }, $.em );

    

    

    /**

     * Bind a function to the emchange event of each matched element.

     *

     * @example $("p").emchange( function() { alert("Hello"); } );

     *

     * @name emchange

     * @type jQuery

     * @param Function fn A function to bind to the emchange event.

     * @cat Plugins/Em

     */



    /**

     * Trigger the emchange event of each matched element.

     *

     * @example $("p").emchange()

     *

     * @name emchange

     * @type jQuery

     * @cat Plugins/Em

     */

    $.fn[eventName] = function(fn) { return fn ? this.bind(eventName, fn)

                                               : this.trigger(eventName); };

    

    

    // Store the initial pixel value of the user agent s font size.

    $.em.current = $.em.element.offsetWidth / 100;

    

    /**

     * While polling for font-size changes, $.em.iid stores the intervalID in

     * case you should want to cancel with clearInterval().

     *

     * @example window.clearInterval( $.em.iid );

     * 

     * @property

     * @name iid

     * @type Number

     * @cat Plugins/Em

     */

    $.em.iid = setInterval( $.em.action, $.em.delay );

});