Support for rounded bar chart and grid edges

Source/Charts/Data/Implementations/Standard/BarChartDataSet.swift

@@ -51,6 +51,9 @@ open class BarChartDataSet: BarLineScatterCandleBubbleChartDataSet, BarChartData
     /// the overall entry count, including counting each stack-value individually
     private var _entryCountStacks = 0
 
+    /// the corner radius applied to each data set
+        public var cornerRadius: CGFloat = 0.0
+
     /// Calculates the total number of entries this DataSet represents, including
     /// stacks. All values belonging to a stack are calculated separately.
     private func calcEntryCountIncludingStacks(entries: [BarChartDataEntry])

Source/Charts/Data/Interfaces/BarChartDataSetProtocol.swift

@@ -39,4 +39,7 @@ public protocol BarChartDataSetProtocol: BarLineScatterCandleBubbleChartDataSetP
 
     /// array of labels used to describe the different values of the stacked bars
     var stackLabels: [String] { get set }
+
+    /// the corner radius applied to each data set
+        var cornerRadius: CGFloat { get set }
 }

Source/Charts/Renderers/BarChartRenderer.swift

@@ -379,7 +379,7 @@ open class BarChartRenderer: BarLineScatterCandleBubbleRenderer
                 context.setFillColor(dataSet.color(atIndex: j).cgColor)
             }
 
-            context.fill(barRect)
+            setRoundedCorners(context: context, barRect: barRect, dataSet: dataSet as! BarChartDataSet)
 
             if drawBorder
             {
@@ -406,6 +406,12 @@ open class BarChartRenderer: BarLineScatterCandleBubbleRenderer
         }
     }
 
+    func setRoundedCorners(context: CGContext, barRect: CGRect, dataSet: BarChartDataSet) {
+        let bezierPath = UIBezierPath(roundedRect: barRect, cornerRadius: barRect.width * dataSet.cornerRadius)
+                        context.addPath(bezierPath.cgPath)
+                        context.drawPath(using: .fill)
+    }
+
     open func prepareBarHighlight(
         x: Double,
           y1: Double,

Source/Charts/Renderers/HorizontalBarChartRenderer.swift

@@ -228,7 +228,8 @@ open class HorizontalBarChartRenderer: BarChartRenderer
                 _barShadowRectBuffer.size.width = viewPortHandler.contentWidth
 
                 context.setFillColor(dataSet.barShadowColor.cgColor)
-                context.fill(_barShadowRectBuffer)
+                // to round the edges for each bar's shadow
+                setRoundedCorners(context: context, barRect: _barShadowRectBuffer, dataSet: dataSet as! BarChartDataSet)
             }
         }
 
@@ -265,7 +266,8 @@ open class HorizontalBarChartRenderer: BarChartRenderer
                 context.setFillColor(dataSet.color(atIndex: j).cgColor)
             }
 
-            context.fill(barRect)
+            // to round the edges for each bar
+            setRoundedCorners(context: context, barRect: barRect, dataSet: dataSet as! BarChartDataSet)
 
             if drawBorder
             {

Source/Charts/Renderers/XAxisRenderer.swift

@@ -341,7 +341,10 @@ open class XAxisRenderer: NSObject, AxisRenderer
         context.saveGState()
         defer { context.restoreGState() }
 
-        context.clip(to: self.gridClippingRect)
+        // clip when line cap is not round to have rounded edges for grid
+        if axis.gridLineCap != .round {
+            context.clip(to: self.gridClippingRect)
+        }
 
         context.setShouldAntialias(axis.gridAntialiasEnabled)
         context.setStrokeColor(axis.gridColor.cgColor)