helpers.js

angular.module('duScroll.scrollHelpers', ['duScroll.requestAnimation'])
.run(function($window, $q, cancelAnimation, requestAnimation, duScrollEasing, duScrollDuration, duScrollOffset, duScrollCancelOnEvents) {
  'use strict';

  var proto = {};

  var isDocument = function(el) {
    return (typeof HTMLDocument !== 'undefined' && el instanceof HTMLDocument) || (el.nodeType && el.nodeType === el.DOCUMENT_NODE);
  };

  var isElement = function(el) {
    return (typeof HTMLElement !== 'undefined' && el instanceof HTMLElement) || (el.nodeType && el.nodeType === el.ELEMENT_NODE);
  };

  var unwrap = function(el) {
    return isElement(el) || isDocument(el) ? el : el[0];
  };

  proto.duScrollTo = function(left, top, duration, easing) {
    var aliasFn;
    if(angular.isElement(left)) {
      aliasFn = this.duScrollToElement;
    } else if(angular.isDefined(duration)) {
      aliasFn = this.duScrollToAnimated;
    }
    if(aliasFn) {
      return aliasFn.apply(this, arguments);
    }
    var el = unwrap(this);
    if(isDocument(el)) {
      return $window.scrollTo(left, top);
    }
    el.scrollLeft = left;
    el.scrollTop = top;
  };

  var scrollAnimation, deferred;
  proto.duScrollToAnimated = function(left, top, duration, easing) {
    if(duration && !easing) {
      easing = duScrollEasing;
    }
    var startLeft = this.duScrollLeft(),
        startTop = this.duScrollTop(),
        deltaLeft = Math.round(left - startLeft),
        deltaTop = Math.round(top - startTop);

    var startTime = null, progress = 0;
    var el = this;

    var cancelScrollAnimation = function($event){
      if(!$event || (progress && ($event.which > 0 || $event.type === 'wheel' || $event.type === 'mousedown' || $event.type === 'mousewheel'))){
        if(duScrollCancelOnEvents) {
          el.unbind(duScrollCancelOnEvents, cancelScrollAnimation);
        }
        cancelAnimation(scrollAnimation);
        deferred.reject();
        scrollAnimation = null;
      }
    };

    if(scrollAnimation) {
      cancelScrollAnimation();
    }
    deferred = $q.defer();

    var elem = unwrap(el);
    var isScrollBottom = false;
    var scrollY;
    if(isDocument(elem)){
        scrollY = $window.scrollY || elem.documentElement.scrollTop || elem.body.scrollTop;
        isScrollBottom = elem.documentElement.scrollHeight - scrollY === elem.documentElement.clientHeight;
    }
    else if(isElement(elem)){
        isScrollBottom = elem.scrollHeight - elem.scrollTop === elem.clientHeight;
    }

    if(duration === 0 || (!deltaLeft && (!deltaTop || (deltaTop > 0 && isScrollBottom) ))){
      if(duration === 0) {
        el.duScrollTo(left, top);
      }
      deferred.resolve();
      return deferred.promise;
    }

    var animationStep = function(timestamp) {
      if (startTime === null) {
        startTime = timestamp;
      }

      progress = timestamp - startTime;
      var percent = (progress >= duration ? 1 : easing(progress/duration));

      el.scrollTo(
        startLeft + Math.ceil(deltaLeft * percent),
        startTop + Math.ceil(deltaTop * percent)
      );
      if(percent < 1) {
        scrollAnimation = requestAnimation(animationStep);
      } else {
        if(duScrollCancelOnEvents) {
          el.unbind(duScrollCancelOnEvents, cancelScrollAnimation);
        }
        scrollAnimation = null;
        deferred.resolve();
      }
    };

    //Fix random mobile safari bug when scrolling to top by hitting status bar
    el.duScrollTo(startLeft, startTop);

    if(duScrollCancelOnEvents) {
      el.bind(duScrollCancelOnEvents, cancelScrollAnimation);
    }

    scrollAnimation = requestAnimation(animationStep);
    return deferred.promise;
  };

  proto.duScrollToElement = function(target, offset, duration, easing) {
    var el = unwrap(this);
    if(!angular.isNumber(offset) || isNaN(offset)) {
      offset = duScrollOffset;
    }
    var top = this.duScrollTop() + unwrap(target).getBoundingClientRect().top - offset;
    if(isElement(el)) {
      top -= el.getBoundingClientRect().top;
    }
    return this.duScrollTo(0, top, duration, easing);
  };

  proto.duScrollLeft = function(value, duration, easing) {
    if(angular.isNumber(value)) {
      return this.duScrollTo(value, this.duScrollTop(), duration, easing);
    }
    var el = unwrap(this);
    if(isDocument(el)) {
      return $window.scrollX || document.documentElement.scrollLeft || document.body.scrollLeft;
    }
    return el.scrollLeft;
  };
  proto.duScrollTop = function(value, duration, easing) {
    if(angular.isNumber(value)) {
      return this.duScrollTo(this.duScrollLeft(), value, duration, easing);
    }
    var el = unwrap(this);
    if(isDocument(el)) {
      return $window.scrollY || document.documentElement.scrollTop || document.body.scrollTop;
    }
    return el.scrollTop;
  };

  proto.duScrollToElementAnimated = function(target, offset, duration, easing) {
    return this.duScrollToElement(target, offset, duration || duScrollDuration, easing);
  };

  proto.duScrollTopAnimated = function(top, duration, easing) {
    return this.duScrollTop(top, duration || duScrollDuration, easing);
  };

  proto.duScrollLeftAnimated = function(left, duration, easing) {
    return this.duScrollLeft(left, duration || duScrollDuration, easing);
  };

  angular.forEach(proto, function(fn, key) {
    angular.element.prototype[key] = fn;

    //Remove prefix if not already claimed by jQuery / ui.utils
    var unprefixed = key.replace(/^duScroll/, 'scroll');
    if(angular.isUndefined(angular.element.prototype[unprefixed])) {
      angular.element.prototype[unprefixed] = fn;
    }
  });

});