ChartViewBase cleanup (#4537)

* refactor: remove _highlightPerTapEnabled

* refactor: remove _drawUnitInChart

* refactor: remove interceptTouchEvents

* refactor: use abs

* refactor: optional chaining

* refactor: use first

* refactor: use bounds directly

* refactor: use max and min

Source/Charts/Charts/ChartViewBase.swift

@@ -72,16 +72,9 @@ open class ChartViewBase: NSUIView, ChartDataProvider, AnimatorDelegate
         }
     }
 
-    /// Flag that indicates if highlighting per tap (touch) is enabled
-    private var _highlightPerTapEnabled = true
-
     /// If set to true, chart continues to scroll after touch up
     @objc open var dragDecelerationEnabled = true
 
-    /// if true, units are drawn next to the values in the chart
-    // TODO: This is used nowhere and can't be used by a consumer. Can we remove this property?
-    internal var _drawUnitInChart = false
-
     /// The object representing the labels on the x-axis
     @objc open internal(set) lazy var xAxis = XAxis()
 
@@ -142,9 +135,6 @@ open class ChartViewBase: NSUIView, ChartDataProvider, AnimatorDelegate
     /// The marker that is displayed when a value is clicked on the chart
     @objc open var marker: Marker?
 
-    // TODO: There is no way to modify this value. Should it exist?
-    private let interceptTouchEvents = false
-
     /// An extra offset to be appended to the viewport's top
     @objc open var extraTopOffset: CGFloat = 0.0
 
@@ -248,13 +238,11 @@ open class ChartViewBase: NSUIView, ChartDataProvider, AnimatorDelegate
 
         if let data = data , data.entryCount >= 2
         {
-            reference = fabs(max - min)
+            reference = abs(max - min)
         }
         else
         {
-            let absMin = fabs(min)
-            let absMax = fabs(max)
-            reference = absMin > absMax ? absMin : absMax
+            reference = Swift.max(abs(min), abs(max))
         }
 
 
@@ -268,8 +256,7 @@ open class ChartViewBase: NSUIView, ChartDataProvider, AnimatorDelegate
 
     open override func draw(_ rect: CGRect)
     {
-        let optionalContext = NSUIGraphicsGetCurrentContext()
-        guard let context = optionalContext else { return }
+        guard let context = NSUIGraphicsGetCurrentContext() else { return }
 
         if data === nil && !noDataText.isEmpty
         {
@@ -337,12 +324,8 @@ open class ChartViewBase: NSUIView, ChartDataProvider, AnimatorDelegate
     /// Set this to false to prevent values from being highlighted by tap gesture.
     /// Values can still be highlighted via drag or programmatically.
     /// **default**: true
-    @objc open var highlightPerTapEnabled: Bool
-    {
-        get { return _highlightPerTapEnabled }
-        set { _highlightPerTapEnabled = newValue }
-    }
-
+    @objc open var highlightPerTapEnabled: Bool = true
+
     /// `true` if values can be highlighted via tap gesture, `false` ifnot.
     @objc open var isHighLightPerTapEnabled: Bool
     {
@@ -366,10 +349,7 @@ open class ChartViewBase: NSUIView, ChartDataProvider, AnimatorDelegate
         // set the indices to highlight
         highlighted = highs ?? []
 
-        lastHighlighted = highlighted.isEmpty
-            ? nil
-            : highlighted[0]
-
+        lastHighlighted = highlighted.first
 
         // redraw the chart
         setNeedsDisplay()
@@ -701,7 +681,6 @@ open class ChartViewBase: NSUIView, ChartDataProvider, AnimatorDelegate
     /// The center point of the chart (the whole View) in pixels.
     @objc open var midPoint: CGPoint
     {
-        let bounds = self.bounds
         return CGPoint(x: bounds.origin.x + bounds.size.width / 2.0, y: bounds.origin.y + bounds.size.height / 2.0)
     }
 
@@ -859,12 +838,7 @@ open class ChartViewBase: NSUIView, ChartDataProvider, AnimatorDelegate
         }
         set
         {
-            switch newValue
-            {
-            case ..<0.0: _dragDecelerationFrictionCoef = 0
-            case 1.0...: _dragDecelerationFrictionCoef = 0.999
-            default: _dragDecelerationFrictionCoef = newValue
-            }
+            _dragDecelerationFrictionCoef = max(0, min(newValue, 0.999))
         }
     }
     private var _dragDecelerationFrictionCoef: CGFloat = 0.9
@@ -895,33 +869,21 @@ open class ChartViewBase: NSUIView, ChartDataProvider, AnimatorDelegate
 
     open override func nsuiTouchesBegan(_ touches: Set<NSUITouch>, withEvent event: NSUIEvent?)
     {
-        if !interceptTouchEvents
-        {
-            super.nsuiTouchesBegan(touches, withEvent: event)
-        }
+        super.nsuiTouchesBegan(touches, withEvent: event)
     }
 
     open override func nsuiTouchesMoved(_ touches: Set<NSUITouch>, withEvent event: NSUIEvent?)
     {
-        if !interceptTouchEvents
-        {
-            super.nsuiTouchesMoved(touches, withEvent: event)
-        }
+        super.nsuiTouchesMoved(touches, withEvent: event)
     }
 
     open override func nsuiTouchesEnded(_ touches: Set<NSUITouch>, withEvent event: NSUIEvent?)
     {
-        if !interceptTouchEvents
-        {
-            super.nsuiTouchesEnded(touches, withEvent: event)
-        }
+        super.nsuiTouchesEnded(touches, withEvent: event)
     }
 
     open override func nsuiTouchesCancelled(_ touches: Set<NSUITouch>?, withEvent event: NSUIEvent?)
     {
-        if !interceptTouchEvents
-        {
-            super.nsuiTouchesCancelled(touches, withEvent: event)
-        }
+        super.nsuiTouchesCancelled(touches, withEvent: event)
     }
 }