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/**
* @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 );
});
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