http://www.wcssp.org/modules/mod_superfish_menu/js/jquery.hoverIntent.js

1/**
2* hoverIntent is similar to jQuery's built-in "hover" function except that
3* instead of firing the onMouseOver event immediately, hoverIntent checks
4* to see if the user's mouse has slowed down (beneath the sensitivity
5* threshold) before firing the onMouseOver event.
6* 
7* hoverIntent r6 // 2011.02.26 // jQuery 1.5.1+
8* <http://cherne.net/brian/resources/jquery.hoverIntent.html>
9* 
10* hoverIntent is currently available for use in all personal or commercial 
11* projects under both MIT and GPL licenses. This means that you can choose 
12* the license that best suits your project, and use it accordingly.
13* 
14* // basic usage (just like .hover) receives onMouseOver and onMouseOut functions
15* $("ul li").hoverIntent( showNav , hideNav );
16* 
17* // advanced usage receives configuration object only
18* $("ul li").hoverIntent({
19*	sensitivity: 7, // number = sensitivity threshold (must be 1 or higher)
20*	interval: 100,   // number = milliseconds of polling interval
21*	over: showNav,  // function = onMouseOver callback (required)
22*	timeout: 0,   // number = milliseconds delay before onMouseOut function call
23*	out: hideNav    // function = onMouseOut callback (required)
24* });
25* 
26* @param  f  onMouseOver function || An object with configuration options
27* @param  g  onMouseOut function  || Nothing (use configuration options object)
28* @author    Brian Cherne brian(at)cherne(dot)net
29*/
30(function($) {
31	$.fn.hoverIntent = function(f,g) {
32		// default configuration options
33		var cfg = {
34			sensitivity: 7,
35			interval: 100,
36			timeout: 0
37		};
38		// override configuration options with user supplied object
39		cfg = $.extend(cfg, g ? { over: f, out: g } : f );
40
41		// instantiate variables
42		// cX, cY = current X and Y position of mouse, updated by mousemove event
43		// pX, pY = previous X and Y position of mouse, set by mouseover and polling interval
44		var cX, cY, pX, pY;
45
46		// A private function for getting mouse position
47		var track = function(ev) {
48			cX = ev.pageX;
49			cY = ev.pageY;
50		};
51
52		// A private function for comparing current and previous mouse position
53		var compare = function(ev,ob) {
54			ob.hoverIntent_t = clearTimeout(ob.hoverIntent_t);
55			// compare mouse positions to see if they've crossed the threshold
56			if ( ( Math.abs(pX-cX) + Math.abs(pY-cY) ) < cfg.sensitivity ) {
57				$(ob).unbind("mousemove",track);
58				// set hoverIntent state to true (so mouseOut can be called)
59				ob.hoverIntent_s = 1;
60				return cfg.over.apply(ob,[ev]);
61			} else {
62				// set previous coordinates for next time
63				pX = cX; pY = cY;
64				// use self-calling timeout, guarantees intervals are spaced out properly (avoids JavaScript timer bugs)
65				ob.hoverIntent_t = setTimeout( function(){compare(ev, ob);} , cfg.interval );
66			}
67		};
68
69		// A private function for delaying the mouseOut function
70		var delay = function(ev,ob) {
71			ob.hoverIntent_t = clearTimeout(ob.hoverIntent_t);
72			ob.hoverIntent_s = 0;
73			return cfg.out.apply(ob,[ev]);
74		};
75
76		// A private function for handling mouse 'hovering'
77		var handleHover = function(e) {
78			// copy objects to be passed into t (required for event object to be passed in IE)
79			var ev = jQuery.extend({},e);
80			var ob = this;
81
82			// cancel hoverIntent timer if it exists
83			if (ob.hoverIntent_t) { ob.hoverIntent_t = clearTimeout(ob.hoverIntent_t); }
84
85			// if e.type == "mouseenter"
86			if (e.type == "mouseenter") {
87				// set "previous" X and Y position based on initial entry point
88				pX = ev.pageX; pY = ev.pageY;
89				// update "current" X and Y position based on mousemove
90				$(ob).bind("mousemove",track);
91				// start polling interval (self-calling timeout) to compare mouse coordinates over time
92				if (ob.hoverIntent_s != 1) { ob.hoverIntent_t = setTimeout( function(){compare(ev,ob);} , cfg.interval );}
93
94			// else e.type == "mouseleave"
95			} else {
96				// unbind expensive mousemove event
97				$(ob).unbind("mousemove",track);
98				// if hoverIntent state is true, then call the mouseOut function after the specified delay
99				if (ob.hoverIntent_s == 1) { ob.hoverIntent_t = setTimeout( function(){delay(ev,ob);} , cfg.timeout );}
100			}
101		};
102
103		// bind the function to the two event listeners
104		return this.bind('mouseenter',handleHover).bind('mouseleave',handleHover);
105	};
106})(jQuery);