"

From 2014.igem.org

/**

* Created by IntelliJ IDEA.
*
* User: phil
* Date: 15/11/12
* Time: 11:04 AM
*
*/

(function ($) {

   var self = this, container, running=false, currentY = 0, targetY = 0, oldY = 0, maxScrollTop= 0, minScrollTop, direction, onRenderCallback=null,
           fricton = 0.95, // higher value for slower deceleration
           vy = 0,
           stepAmt = 1,
           minMovement= 0.1,
           ts=0.1;

   var updateScrollTarget = function (amt) {
       targetY += amt;
       vy += (targetY - oldY) * stepAmt;
     
       oldY = targetY;

   }
   var render = function () {
       if (vy < -(minMovement) || vy > minMovement) {

           currentY = (currentY + vy);
           if (currentY > maxScrollTop) {
               currentY = vy = 0;
           } else if (currentY < minScrollTop) {
                   vy = 0;
                   currentY = minScrollTop;
               }
          
           container.scrollTop(-currentY);

           vy *= fricton;
           
        //   vy += ts * (currentY-targetY);
           // scrollTopTweened += settings.tweenSpeed * (scrollTop - scrollTopTweened);
           // currentY += ts * (targetY - currentY);

           if(onRenderCallback){
               onRenderCallback();
           }
       }
   }
   var animateLoop = function () {
       if(! running)return;
       requestAnimFrame(animateLoop);
       render();
       //log("45","animateLoop","animateLoop", "",stop);
   }
   var onWheel = function (e) {
       e.preventDefault();
       var evt = e.originalEvent;
      
       var delta = evt.detail ? evt.detail * -1 : evt.wheelDelta / 40;
       var dir = delta < 0 ? -1 : 1;
       if (dir != direction) {
           vy = 0;
           direction = dir;
       }

       //reset currentY in case non-wheel scroll has occurred (scrollbar drag, etc.)
       currentY = -container.scrollTop();
       
       updateScrollTarget(delta);
   }

   /*
    * http://paulirish.com/2011/requestanimationframe-for-smart-animating/
    */
   window.requestAnimFrame = (function () {
       return  window.requestAnimationFrame ||
               window.webkitRequestAnimationFrame ||
               window.mozRequestAnimationFrame ||
               window.oRequestAnimationFrame ||
               window.msRequestAnimationFrame ||
               function (callback) {
                   window.setTimeout(callback, 1000 / 60);
               }; 
             
               
   })();

   /*
    * http://jsbin.com/iqafek/2/edit
    */
   var normalizeWheelDelta = function () {
       // Keep a distribution of observed values, and scale by the
       // 33rd percentile.
       var distribution = [], done = null, scale = 30;
       return function (n) {
           // Zeroes don't count.
           if (n == 0) return n;
           // After 500 samples, we stop sampling and keep current factor.
           if (done != null) return n * done;
           var abs = Math.abs(n);
           // Insert value (sorted in ascending order).
           outer: do { // Just used for break goto
               for (var i = 0; i < distribution.length; ++i) {
                   if (abs <= distribution[i]) {
                       distribution.splice(i, 0, abs);
                       break outer;
                   }
               }
               distribution.push(abs);
           } while (false);
           // Factor is scale divided by 33rd percentile.
           var factor = scale / distribution[Math.floor(distribution.length / 3)];
           if (distribution.length == 500) done = factor;
           return n * factor;
       };
   }();

   $.fn.smoothWheel = function () {
       //  var args = [].splice.call(arguments, 0);
       var options = jQuery.extend({}, arguments[0]);
       return this.each(function (index, elm) {

           if(!('ontouchstart' in window)){
               container = $(this);
               container.bind("mousewheel", onWheel);
               container.bind("DOMMouseScroll", onWheel);

               //set target/old/current Y to match current scroll position to prevent jump to top of container
               targetY = oldY = container.get(0).scrollTop;
               currentY = -targetY;
               
               minScrollTop = container.get(0).clientHeight - container.get(0).scrollHeight;
               if(options.onRender){
                   onRenderCallback = options.onRender;
               }
               if(options.remove){
                   log("122","smoothWheel","remove", "");
                   running=false;
                   container.unbind("mousewheel", onWheel);
                   container.unbind("DOMMouseScroll", onWheel);
               }else if(!running){
                   running=true;
                   animateLoop();
               }

           }
       });
   };

})(jQuery);