Posibility to add Corner Radius for rounded bars in bar chart

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

@@ -51,6 +51,34 @@ 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
+
+    /// array of corners to be rounded
+    open var roundedCorners: UIRectCorner = [] {
+        didSet {
+            var invertedCorners: UIRectCorner = []
+            if roundedCorners.contains(.topLeft) {
+                invertedCorners.insert(.bottomLeft)
+            }
+            if roundedCorners.contains(.topRight) {
+                invertedCorners.insert(.bottomRight)
+            }
+            if roundedCorners.contains(.bottomLeft) {
+                invertedCorners.insert(.topLeft)
+            }
+            if roundedCorners.contains(.bottomRight) {
+                invertedCorners.insert(.topRight)
+            }
+            if roundedCorners.contains(.allCorners) {
+                invertedCorners.insert(.allCorners)
+            }
+            roundedCornersInverted = invertedCorners
+        }
+    }
+
+    open private(set) var roundedCornersInverted: UIRectCorner = []
+
     /// 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

@@ -12,6 +12,10 @@
 import Foundation
 import CoreGraphics
 
+#if canImport(UIKit)
+import UIKit
+#endif
+
 @objc
 public protocol BarChartDataSetProtocol: BarLineScatterCandleBubbleChartDataSetProtocol
 {
@@ -39,4 +43,13 @@ 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 }
+
+    /// array of corners to be rounded
+    var roundedCorners: UIRectCorner { get set }
+
+    /// array of corners to be rounded
+    var roundedCornersInverted: UIRectCorner { get }
 }

Source/Charts/Renderers/BarChartRenderer.swift

@@ -351,7 +351,17 @@ open class BarChartRenderer: BarLineScatterCandleBubbleRenderer
                 guard viewPortHandler.isInBoundsRight(barRect.origin.x) else { break }
 
                 context.setFillColor(dataSet.barShadowColor.cgColor)
-                context.fill(barRect)
+
+                var roundedCorners = dataSet.roundedCorners
+                if let i = buffer.firstIndex(of: barRect),
+                   let entry = dataSet.entryForIndex(i),
+                   entry.y < 0 {
+                    roundedCorners = dataSet.roundedCornersInverted
+                }
+                let bezierPath = UIBezierPath(roundedRect: barRect, byRoundingCorners: roundedCorners,
+                                              cornerRadii: .init(width: dataSet.cornerRadius, height: dataSet.cornerRadius))
+                context.addPath(bezierPath.cgPath)
+                context.drawPath(using: .fill)
             }
         }
 
@@ -379,7 +389,15 @@ open class BarChartRenderer: BarLineScatterCandleBubbleRenderer
                 context.setFillColor(dataSet.color(atIndex: j).cgColor)
             }
 
-            context.fill(barRect)
+            var roundedCorners = dataSet.roundedCorners
+            if let entry = dataSet.entryForIndex(j),
+               entry.y < 0 {
+                roundedCorners = dataSet.roundedCornersInverted
+            }
+            let bezierPath = UIBezierPath(roundedRect: barRect, byRoundingCorners: roundedCorners,
+                                          cornerRadii: .init(width: dataSet.cornerRadius, height: dataSet.cornerRadius))
+            context.addPath(bezierPath.cgPath)
+            context.drawPath(using: .fill)
 
             if drawBorder
             {
@@ -744,7 +762,14 @@ open class BarChartRenderer: BarLineScatterCandleBubbleRenderer
 
                 setHighlightDrawPos(highlight: high, barRect: barRect)
 
-                context.fill(barRect)
+                var roundedCorners = set.roundedCorners
+                if e.y < 0 {
+                    roundedCorners = set.roundedCornersInverted
+                }
+                let bezierPath = UIBezierPath(roundedRect: barRect, byRoundingCorners: roundedCorners,
+                                              cornerRadii: .init(width: set.cornerRadius, height: set.cornerRadius))
+                context.addPath(bezierPath.cgPath)
+                context.drawPath(using: .fill)
             }
         }
     }

Source/Charts/Renderers/HorizontalBarChartRenderer.swift

@@ -228,7 +228,15 @@ open class HorizontalBarChartRenderer: BarChartRenderer
                 _barShadowRectBuffer.size.width = viewPortHandler.contentWidth
 
                 context.setFillColor(dataSet.barShadowColor.cgColor)
-                context.fill(_barShadowRectBuffer)
+
+                var roundedCorners = dataSet.roundedCorners
+                if e.x < 0 {
+                    roundedCorners = dataSet.roundedCornersInverted
+                }
+                let bezierPath = UIBezierPath(roundedRect: _barShadowRectBuffer, byRoundingCorners: roundedCorners,
+                                              cornerRadii: .init(width: dataSet.cornerRadius, height: dataSet.cornerRadius))
+                context.addPath(bezierPath.cgPath)
+                context.drawPath(using: .fill)
             }
         }
 
@@ -265,7 +273,15 @@ open class HorizontalBarChartRenderer: BarChartRenderer
                 context.setFillColor(dataSet.color(atIndex: j).cgColor)
             }
 
-            context.fill(barRect)
+            var roundedCorners = dataSet.roundedCorners
+            if let entry = dataSet.entryForIndex(j),
+               entry.x < 0 {
+                roundedCorners = dataSet.roundedCornersInverted
+            }
+            let bezierPath = UIBezierPath(roundedRect: barRect, byRoundingCorners: roundedCorners,
+                                          cornerRadii: .init(width: dataSet.cornerRadius, height: dataSet.cornerRadius))
+            context.addPath(bezierPath.cgPath)
+            context.drawPath(using: .fill)
 
             if drawBorder
             {