Adding a minimum parameter to setVisibleXRange

Charts/Classes/Charts/BarLineChartViewBase.swift

@@ -619,7 +619,9 @@ public class BarLineChartViewBase: ChartViewBase, UIGestureRecognizerDelegate
         }
         else if (recognizer.state == UIGestureRecognizerState.Changed)
         {
-            if (_isScaling)
+            var isZoomingOut = (recognizer.scale < 1);
+            var canZoomMore = isZoomingOut ? _viewPortHandler.canZoomOutMore() : _viewPortHandler.canZoomInMore();
+            if (_isScaling && canZoomMore)
             {
                 var location = recognizer.locationInView(self);
                 location.x = location.x - _viewPortHandler.offsetLeft;
@@ -939,6 +941,16 @@ public class BarLineChartViewBase: ChartViewBase, UIGestureRecognizerDelegate
         _viewPortHandler.setMinimumScaleX(xScale);
     }
 
+    //Limits the maximal and minimal values count that can be visible by pinching and zooming.
+    //e.g. minRange=10, maxRange=100 no less than 10 values and no more that 100 values can be viewed
+    //at once without scrolling
+    public func setVisibleXRange(#minRange: CGFloat, maxRange: CGFloat)
+    {
+        var maxScale = _deltaX / (minRange);
+        var minScale = _deltaX / (maxRange);
+        _viewPortHandler.setScaleXRange(minScaleX: minScale, maxScaleX: maxScale);
+    }
+
     /// Sets the size of the area (range on the y-axis) that should be maximum visible at once.
     /// 
     /// :param: yRange

Charts/Classes/Utils/ChartViewPortHandler.swift

@@ -31,6 +31,9 @@ public class ChartViewPortHandler: NSObject
     /// minimum scale value on the x-axis
     private var _minScaleX = CGFloat(1.0);
 
+    /// maximum scale value on the x-axis
+    private var _maxScaleX = CGFloat(FLT_MAX);
+
     /// contains the current scale factor of the x-axis
     private var _scaleX = CGFloat(1.0);
 
@@ -208,6 +211,11 @@ public class ChartViewPortHandler: NSObject
         // min scale-x is 1f
         _scaleX = max(_minScaleX, matrix.a);
 
+        if (_scaleX > _maxScaleX)
+        {
+            _scaleX = _maxScaleX;
+        }
+
         // min scale-y is 1f
         _scaleY = max(_minScaleY, matrix.d);
 
@@ -393,4 +401,20 @@ public class ChartViewPortHandler: NSObject
     {
         return _transOffsetX <= 0.0 && _transOffsetY <= 0.0 ? true : false;
     }
+
+    public func setScaleXRange(#minScaleX: CGFloat, maxScaleX: CGFloat)
+    {
+        _maxScaleX = maxScaleX;
+        setMinimumScaleX(minScaleX);
+    }
+
+    public func canZoomOutMore() -> Bool
+    {
+        return (_scaleX > _minScaleX);
+    }
+
+    public func canZoomInMore() -> Bool
+    {
+        return (_scaleX < _maxScaleX);
+    }
 }