Template:Tsinghua-A/JS/hoverIntent

/**

* hoverIntent is similar to jQuery's built-in "hover" method except that
* instead of firing the handlerIn function immediately, hoverIntent checks
* to see if the user's mouse has slowed down (beneath the sensitivity
* threshold) before firing the event. The handlerOut function is only
* called after a matching handlerIn.
*
* hoverIntent r7 // 2013.03.11 // jQuery 1.9.1+
* http://cherne.net/brian/resources/jquery.hoverIntent.html
*
* You may use hoverIntent under the terms of the MIT license. Basically that
* means you are free to use hoverIntent as long as this header is left intact.
* Copyright 2007, 2013 Brian Cherne
*
* // basic usage ... just like .hover()
* .hoverIntent( handlerIn, handlerOut )
* .hoverIntent( handlerInOut )
*
* // basic usage ... with event delegation!
* .hoverIntent( handlerIn, handlerOut, selector )
* .hoverIntent( handlerInOut, selector )
*
* // using a basic configuration object
* .hoverIntent( config )
*
* @param  handlerIn   function OR configuration object
* @param  handlerOut  function OR selector for delegation OR undefined
* @param  selector    selector OR undefined
* @author Brian Cherne <brian(at)cherne(dot)net>
**/

(function($) {

   $.fn.hoverIntent = function(handlerIn,handlerOut,selector) {

       // default configuration values
       var cfg = {
           interval: 100,
           sensitivity: 7,
           timeout: 0
       };

       if ( typeof handlerIn === "object" ) {
           cfg = $.extend(cfg, handlerIn );
       } else if ($.isFunction(handlerOut)) {
           cfg = $.extend(cfg, { over: handlerIn, out: handlerOut, selector: selector } );
       } else {
           cfg = $.extend(cfg, { over: handlerIn, out: handlerIn, selector: handlerOut } );
       }

       // 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).off("mousemove.hoverIntent",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).on("mousemove.hoverIntent",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).off("mousemove.hoverIntent",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 );}
           }
       };

       // listen for mouseenter and mouseleave
       return this.on({'mouseenter.hoverIntent':handleHover,'mouseleave.hoverIntent':handleHover}, cfg.selector);
   };

})(jQuery);