AutoScaling yAxis during panning / zooming

Charts/Classes/Charts/BarLineChartViewBase.swift

@@ -24,6 +24,7 @@ public class BarLineChartViewBase: ChartViewBase, UIGestureRecognizerDelegate
     private var _pinchZoomEnabled = false
     private var _doubleTapToZoomEnabled = true
     private var _dragEnabled = true
+    private var _autoScaleMinMaxEnabled = false;
 
     private var _scaleXEnabled = true
     private var _scaleYEnabled = true
@@ -153,6 +154,12 @@ public class BarLineChartViewBase: ChartViewBase, UIGestureRecognizerDelegate
         _leftYAxisRenderer?.renderAxisLine(context: context);
         _rightYAxisRenderer?.renderAxisLine(context: context);
 
+        if (_autoScaleMinMaxEnabled)
+        {
+            calcMinMax();
+            calculateOffsets();
+        }
+
         // make sure the graph values and grid cannot be drawn outside the content-rect
         CGContextSaveGState(context);
 
@@ -256,6 +263,11 @@ public class BarLineChartViewBase: ChartViewBase, UIGestureRecognizerDelegate
 
     internal override func calcMinMax()
     {
+        if (_autoScaleMinMaxEnabled)
+        {
+            _data.calcMinMax(start: lowestVisibleXIndex, end: highestVisibleXIndex);
+        }
+
         var minLeft = _data.getYMin(.Left);
         var maxLeft = _data.getYMax(.Left);
         var minRight = _data.getYMin(.Right);
@@ -864,7 +876,7 @@ public class BarLineChartViewBase: ChartViewBase, UIGestureRecognizerDelegate
 
     /// Zooms in or out by the given scale factor. x and y are the coordinates
     /// (in pixels) of the zoom center.
-    /// 
+    ///
     /// :param: scaleX if < 1f --> zoom out, if > 1f --> zoom in
     /// :param: scaleY if < 1f --> zoom out, if > 1f --> zoom in
     /// :param: x
@@ -1470,6 +1482,27 @@ public class BarLineChartViewBase: ChartViewBase, UIGestureRecognizerDelegate
     {
         return _leftAxis.isInverted || _rightAxis.isInverted;
     }
+
+    /// flat that indicates if auto scaling on the y axis is enabled.
+    /// if yes, the y axis automatically adjusts to the min and max y values of the current x axis range
+    public var autoScaleMinMaxEnabled: Bool
+        {
+        get
+        {
+            return _autoScaleMinMaxEnabled;
+        }
+        set
+        {
+            if (_autoScaleMinMaxEnabled != newValue)
+            {
+                _autoScaleMinMaxEnabled = newValue;
+            }
+        }
+    }
+
+    /// returns true if autoScaleMinMax is enabled, false if no
+    /// :default: false
+    public var isAutoScaleMinMaxEnabled : Bool { return autoScaleMinMaxEnabled; }
 }
 
 /// Default formatter that calculates the position of the filled line.

Charts/Classes/Data/CandleChartDataSet.swift

@@ -45,27 +45,41 @@ public class CandleChartDataSet: BarLineScatterCandleChartDataSet
         super.init(yVals: yVals, label: label);
     }
 
-    internal override func calcMinMax()
+    internal override func calcMinMax(#start: Int, end: Int)
     {
         if (yVals.count == 0)
         {
             return;
         }
 
         var entries = yVals as! [CandleChartDataEntry];
-
-        _yMin = entries[0].low;
-        _yMax = entries[0].high;
-
-        for (var i = 0; i < entries.count; i++)
+
+        var endValue : Int;
+
+        if end == 0
+        {
+            endValue = entries.count - 1;
+        }
+        else
+        {
+            endValue = end;
+        }
+
+        _lastStart = start;
+        _lastEnd = end;
+
+        _yMin = entries[start].low;
+        _yMax = entries[start].high;
+
+        for (var i = 0; i <= endValue; i++)
         {
             var e = entries[i];
-
+            
             if (e.low < _yMin)
             {
                 _yMin = e.low;
             }
-
+            
             if (e.high > _yMax)
             {
                 _yMax = e.high;

Charts/Classes/Data/ChartData.swift

@@ -25,6 +25,8 @@ public class ChartData: NSObject
     internal var _rightAxisMin = Float(0.0)
     private var _yValueSum = Float(0.0)
     private var _yValCount = Int(0)
+    internal var _lastStart = Int(0);
+    internal var _lastEnd = Int(0);
 
     /// the average length (in characters) across all x-value strings
     private var _xValAverageLength = Float(0.0)
@@ -69,7 +71,7 @@ public class ChartData: NSObject
     {
         checkIsLegal(dataSets);
 
-        calcMinMax();
+        calcMinMax(start: _lastStart, end: _lastEnd);
         calcYValueSum();
         calcYValueCount();
 
@@ -120,21 +122,27 @@ public class ChartData: NSObject
     }
 
     /// calc minimum and maximum y value over all datasets
-    internal func calcMinMax()
+    internal func calcMinMax(#start: Int, end: Int)
     {
+
         if (_dataSets == nil || _dataSets.count < 1)
         {
             _yMax = 0.0;
             _yMin = 0.0;
         }
         else
         {
+            _lastStart = start;
+            _lastEnd = end;
+
             // calculate absolute min and max
             _yMin = _dataSets[0].yMin;
             _yMax = _dataSets[0].yMax;
 
             for (var i = 0; i < _dataSets.count; i++)
             {
+                _dataSets[i].calcMinMax(start: start, end: end);
+
                 if (_dataSets[i].yMin < _yMin)
                 {
                     _yMin = _dataSets[i].yMin;
@@ -552,7 +560,7 @@ public class ChartData: NSObject
         _yValCount -= d.entryCount;
         _yValueSum -= d.yValueSum;
 
-        calcMinMax();
+        calcMinMax(start: _lastStart, end: _lastEnd);
 
         return true;
     }
@@ -629,7 +637,7 @@ public class ChartData: NSObject
             _yValCount -= 1;
             _yValueSum -= val;
 
-            calcMinMax();
+            calcMinMax(start: _lastStart, end: _lastEnd);
         }
 
         return removed;

Charts/Classes/Data/ChartDataSet.swift

@@ -22,6 +22,8 @@ public class ChartDataSet: NSObject
     internal var _yMax = Float(0.0)
     internal var _yMin = Float(0.0)
     internal var _yValueSum = Float(0.0)
+    internal var _lastStart = 0;
+    internal var _lastEnd = 0;
     public var label = "DataSet"
     public var visible = true;
     public var drawValuesEnabled = true;
@@ -58,7 +60,7 @@ public class ChartDataSet: NSObject
         // default color
         colors.append(UIColor(red: 140.0/255.0, green: 234.0/255.0, blue: 255.0/255.0, alpha: 1.0));
 
-        self.calcMinMax();
+        self.calcMinMax(start: _lastStart, end: _lastEnd);
         self.calcYValueSum();
     }
 
@@ -70,21 +72,35 @@ public class ChartDataSet: NSObject
     /// Use this method to tell the data set that the underlying data has changed
     public func notifyDataSetChanged()
     {
-        calcMinMax();
+        calcMinMax(start: _lastStart, end: _lastEnd);
         calcYValueSum();
     }
 
-    internal func calcMinMax()
+    internal func calcMinMax(#start : Int, end: Int)
     {
         if _yVals!.count == 0
         {
             return;
         }
 
-        _yMin = yVals[0].value;
-        _yMax = yVals[0].value;
+        var endValue : Int;
 
-        for var i = 0; i < _yVals.count; i++
+        if end == 0
+        {
+            endValue = _yVals.count - 1;
+        }
+        else
+        {
+            endValue = end;
+        }
+
+        _lastStart = start;
+        _lastEnd = endValue;
+
+        _yMin = yVals[start].value;
+        _yMax = yVals[start].value;
+
+        for var i = start; i <= endValue; i++
         {
             let e = _yVals[i];
             if (e.value < _yMin)
@@ -291,7 +307,7 @@ public class ChartDataSet: NSObject
         if (removed)
         {
             _yValueSum -= entry.value;
-            calcMinMax();
+            calcMinMax(start: _lastStart, end: _lastEnd);
         }
 
         return removed;
@@ -305,7 +321,7 @@ public class ChartDataSet: NSObject
             var e = _yVals.removeAtIndex(index);
 
             _yValueSum -= e.value;
-            calcMinMax();
+            calcMinMax(start: _lastStart, end: _lastEnd);
 
             return true;
         }
@@ -348,8 +364,8 @@ public class ChartDataSet: NSObject
         return drawValuesEnabled;
     }
 
-    /// Checks if this DataSet contains the specified Entry. 
-    /// :returns: true if contains the entry, false if not. 
+    /// Checks if this DataSet contains the specified Entry.
+    /// :returns: true if contains the entry, false if not.
     public func contains(e: ChartDataEntry) -> Bool
     {
         for entry in _yVals
@@ -367,6 +383,8 @@ public class ChartDataSet: NSObject
     public func clear()
     {
         _yVals.removeAll(keepCapacity: true);
+        _lastStart = 0;
+        _lastEnd = 0;
         notifyDataSetChanged();
     }
 

Charts/Classes/Data/CombinedChartData.swift

@@ -47,7 +47,7 @@ public class CombinedChartData: BarLineScatterCandleChartData
 
             checkIsLegal(newValue.dataSets);
 
-            calcMinMax();
+            calcMinMax(start: _lastStart, end: _lastEnd);
             calcYValueSum();
             calcYValueCount();
 
@@ -71,7 +71,7 @@ public class CombinedChartData: BarLineScatterCandleChartData
 
             checkIsLegal(newValue.dataSets);
 
-            calcMinMax();
+            calcMinMax(start: _lastStart, end: _lastEnd);
             calcYValueSum();
             calcYValueCount();
 
@@ -95,7 +95,7 @@ public class CombinedChartData: BarLineScatterCandleChartData
 
             checkIsLegal(newValue.dataSets);
 
-            calcMinMax();
+            calcMinMax(start: _lastStart, end: _lastEnd);
             calcYValueSum();
             calcYValueCount();
 
@@ -119,7 +119,7 @@ public class CombinedChartData: BarLineScatterCandleChartData
 
             checkIsLegal(newValue.dataSets);
 
-            calcMinMax();
+            calcMinMax(start: _lastStart, end: _lastEnd);
             calcYValueSum();
             calcYValueCount();
 
@@ -143,7 +143,7 @@ public class CombinedChartData: BarLineScatterCandleChartData
 
             checkIsLegal(newValue.dataSets);
 
-            calcMinMax();
+            calcMinMax(start: _lastStart, end: _lastEnd);
             calcYValueSum();
             calcYValueCount();