feat($ionicScrollDelegate): add scrollBy(left,top,animate) to delegate

Closes #987

Author: deflomu

js/ext/angular/src/controller/ionicScrollController.js

@@ -86,6 +86,14 @@ angular.module('ionic.ui.scroll')
    * @param {boolean=} shouldAnimate Whether the scroll should animate.
    */
   'scrollTo',
+  /**
+   * @ngdoc method
+   * @name $ionicScrollDelegate#scrollBy
+   * @param {number} left The x-offset to scroll by.
+   * @param {number} top The y-offset to scroll by.
+   * @param {boolean=} shouldAnimate Whether the scroll should animate.
+   */
+  'scrollBy',
   /**
    * @ngdoc method
    * @name $ionicScrollDelegate#anchorScroll
@@ -287,6 +295,12 @@ function($scope, scrollViewOptions, $timeout, $window, $$scrollValueCache, $loca
     });
   };
 
+  this.scrollBy = function(left, top, shouldAnimate) {
+    this.resize().then(function() {
+      scrollView.scrollBy(left, top, !!shouldAnimate);
+    });
+  };
+
   this.anchorScroll = function(shouldAnimate) {
     this.resize().then(function() {
       var hash = $location.hash();

js/ext/angular/test/controller/ionicScrollController.unit.js

@@ -257,6 +257,11 @@ describe('$ionicScroll Controller', function() {
           ctrl.scrollTo(1, 2, shouldAnimate);
           expect(ctrl.scrollView.scrollTo).toHaveBeenCalledWith(1, 2, shouldAnimate);
         });
+        it('.scrollBy', function() {
+          spyOn(ctrl.scrollView, 'scrollBy');
+          ctrl.scrollBy(1, 2, shouldAnimate);
+          expect(ctrl.scrollView.scrollBy).toHaveBeenCalledWith(1, 2, shouldAnimate);
+        });
         it('.anchorScroll without hash should scrollTop', inject(function($location, $document) {
           $document[0].getElementById = jasmine.createSpy();
           $location.hash = function() { return null; };

js/views/scrollView.js

@@ -1313,7 +1313,7 @@ ionic.views.Scroll = ionic.views.View.inherit({
    * Scroll by the given offset
    *
    * @param left {Number} Scroll x-axis by given offset
-   * @param top {Number} Scroll x-axis by given offset
+   * @param top {Number} Scroll y-axis by given offset
    * @param animate {Boolean} Whether to animate the given change
    */
   scrollBy: function(left, top, animate) {