newsupernova/lib/web/jquery/jquery.hoverIntent.js

/**
 * hoverIntent is similar to jQuery's built-in "hover" function except that
 * instead of firing the onMouseOver event immediately, hoverIntent checks
 * to see if the user's mouse has slowed down (beneath the sensitivity
 * threshold) before firing the onMouseOver event.
 *
 * hoverIntent r6 // 2011.02.26 // jQuery 1.5.1+
 * <http://cherne.net/brian/resources/jquery.hoverIntent.html>
 *
 * hoverIntent is currently available for use in all personal or commercial
 * projects under both MIT and GPL licenses. This means that you can choose
 * the license that best suits your project, and use it accordingly.
 *
 * // basic usage (just like .hover) receives onMouseOver and onMouseOut functions
 * $("ul li").hoverIntent( showNav , hideNav );
 *
 * // advanced usage receives configuration object only
 * $("ul li").hoverIntent({
*	sensitivity: 7, // number = sensitivity threshold (must be 1 or higher)
*	interval: 100,   // number = milliseconds of polling interval
*	over: showNav,  // function = onMouseOver callback (required)
*	timeout: 0,   // number = milliseconds delay before onMouseOut function call
*	out: hideNav    // function = onMouseOut callback (required)
* });
 *
 * @param  f  onMouseOver function || An object with configuration options
 * @param  g  onMouseOut function  || Nothing (use configuration options object)
 * @author    Brian Cherne brian(at)cherne(dot)net
 */
(function ($) {
    $.fn.hoverIntent = function (f, g) {
        // default configuration options
        var cfg = {
            sensitivity:7,
            interval:100,
            timeout:0
        };
        // override configuration options with user supplied object
        cfg = $.extend(cfg, g ? { over:f, out:g } : f);

        // instantiate variables
        // cX, cY = current X and Y position of mouse, updated by mousemove event
        // pX, pY = previous X and Y position of mouse, set by mouseover and polling interval
        var cX, cY, pX, pY;

        // A private function for getting mouse position
        var track = function (ev) {
            cX = ev.pageX;
            cY = ev.pageY;
        };

        // A private function for comparing current and previous mouse position
        var compare = function (ev, ob) {
            ob.hoverIntent_t = clearTimeout(ob.hoverIntent_t);
            // compare mouse positions to see if they've crossed the threshold
            if (( Math.abs(pX - cX) + Math.abs(pY - cY) ) < cfg.sensitivity) {
                $(ob).unbind("mousemove", track);
                // set hoverIntent state to true (so mouseOut can be called)
                ob.hoverIntent_s = 1;
                return cfg.over.apply(ob, [ev]);
            } else {
                // set previous coordinates for next time
                pX = cX;
                pY = cY;
                // use self-calling timeout, guarantees intervals are spaced out properly (avoids JavaScript timer bugs)
                ob.hoverIntent_t = setTimeout(function () {
                    compare(ev, ob);
                }, cfg.interval);
            }
        };

        // A private function for delaying the mouseOut function
        var delay = function (ev, ob) {
            ob.hoverIntent_t = clearTimeout(ob.hoverIntent_t);
            ob.hoverIntent_s = 0;
            return cfg.out.apply(ob, [ev]);
        };

        // A private function for handling mouse 'hovering'
        var handleHover = function (e) {
            // copy objects to be passed into t (required for event object to be passed in IE)
            var ev = jQuery.extend({}, e);
            var ob = this;

            // cancel hoverIntent timer if it exists
            if (ob.hoverIntent_t) {
                ob.hoverIntent_t = clearTimeout(ob.hoverIntent_t);
            }

            // if e.type == "mouseenter"
            if (e.type == "mouseenter") {
                // set "previous" X and Y position based on initial entry point
                pX = ev.pageX;
                pY = ev.pageY;
                // update "current" X and Y position based on mousemove
                $(ob).bind("mousemove", track);
                // start polling interval (self-calling timeout) to compare mouse coordinates over time
                if (ob.hoverIntent_s != 1) {
                    ob.hoverIntent_t = setTimeout(function () {
                        compare(ev, ob);
                    }, cfg.interval);
                }

                // else e.type == "mouseleave"
            } else {
                // unbind expensive mousemove event
                $(ob).unbind("mousemove", track);
                // if hoverIntent state is true, then call the mouseOut function after the specified delay
                if (ob.hoverIntent_s == 1) {
                    ob.hoverIntent_t = setTimeout(function () {
                        delay(ev, ob);
                    }, cfg.timeout);
                }
            }
        };

        // bind the function to the two event listeners
        return this.bind('mouseenter', handleHover).bind('mouseleave', handleHover);
    };
})(jQuery);