fixed zooming on tablet

lib/timeline/Range.js

@@ -528,19 +528,19 @@ Range.prototype._onPinch = function (event) {
     }
 
     var scale = 1 / (event.gesture.scale + this.scaleOffset);
-    var center = this._pointerToDate(this.props.touch.center);
+    var centerDate = this._pointerToDate(this.props.touch.center);
 
     var hiddenDuration = DateUtil.getHiddenDurationBetween(this.body.hiddenDates, this.start, this.end);
-    var hiddenDurationBefore = DateUtil.getHiddenDurationBefore(this.body.hiddenDates, this, center);
+    var hiddenDurationBefore = DateUtil.getHiddenDurationBefore(this.body.hiddenDates, this, centerDate);
     var hiddenDurationAfter = hiddenDuration - hiddenDurationBefore;
 
     // calculate new start and end
-    var newStart = (center-hiddenDurationBefore) + (this.start - (center-hiddenDurationBefore)) * scale;
-    var newEnd   = (center+hiddenDurationAfter) + (this.end - (center+hiddenDurationAfter)) * scale;
+    var newStart = (centerDate - hiddenDurationBefore) + (this.props.touch.start - (centerDate - hiddenDurationBefore)) * scale;
+    var newEnd = (centerDate + hiddenDurationAfter) + (this.props.touch.end - (centerDate + hiddenDurationAfter)) * scale;
 
     // snapping times away from hidden zones
     this.startToFront = 1 - scale > 0 ? false : true; // used to do the right autocorrection with periodic hidden times
-    this.endToFront   = scale - 1 > 0 ? false : true; // used to do the right autocorrection with periodic hidden times
+    this.endToFront = scale - 1 > 0 ? false : true; // used to do the right autocorrection with periodic hidden times
 
     var safeStart = DateUtil.snapAwayFromHidden(this.body.hiddenDates, newStart, 1 - scale, true);
     var safeEnd = DateUtil.snapAwayFromHidden(this.body.hiddenDates, newEnd, scale - 1, true);