Fix the issue of tracking when the value is equal to the max value an…

…d add tests for this part

Example/Tests/CircularSliderHelperTests.swift

@@ -0,0 +1,50 @@
+//
+//  CircularSliderHelperTests.swift
+//  HGCircularSlider_Tests
+//
+//  Created by Hamza GHAZOUANI on 24/07/2019.
+//  Copyright © 2019 CocoaPods. All rights reserved.
+//
+
+import XCTest
+@testable import HGCircularSlider
+
+extension CGFloat {
+
+    var toDegrees: CGFloat {
+        return self * 180.0 / CGFloat(Double.pi)
+    }
+}
+
+class CircularSliderHelperTests: XCTestCase {
+
+    let cirlceInterval = Interval(min: 0 , max: CGFloat(2 * Double.pi))
+    let valuesInterval = Interval(min: 0, max: 1.2)
+
+    func testInitialValueScale() {
+        // Given
+        let value = valuesInterval.min
+
+        // Thene
+        let angle  = CircularSliderHelper.scaleValue(value, fromInterval: valuesInterval, toInterval: cirlceInterval).toDegrees
+        XCTAssertEqual(angle, 0)
+    }
+
+    func testFinalValueScale() {
+        // Given
+        let value: CGFloat = valuesInterval.max
+
+        // Thene
+        let angle  = CircularSliderHelper.scaleValue(value, fromInterval: valuesInterval, toInterval: cirlceInterval).toDegrees
+        XCTAssertEqual(angle, 360)
+    }
+
+    func testMedianValueScale() {
+        // Given
+        let value: CGFloat = valuesInterval.max / 2
+
+        // Thene
+        let angle  = CircularSliderHelper.scaleValue(value, fromInterval: valuesInterval, toInterval: cirlceInterval).toDegrees
+        XCTAssertEqual(angle, 180)
+    }
+}

HGCircularSlider/Classes/CircularSliderHelper.swift

@@ -13,7 +13,7 @@ internal struct Interval {
     var min: CGFloat = 0.0
     var max: CGFloat = 0.0
     var rounds: Int
-
+    
     init(min: CGFloat, max: CGFloat, rounds: Int = 1) {
         assert(min <= max && rounds > 0, NSLocalizedString("Illegal interval", comment: ""))
 
@@ -42,7 +42,7 @@ internal struct Arc {
     var endAngle: CGFloat = 0.0
 
     init(circle: Circle, startAngle: CGFloat, endAngle: CGFloat) {
-
+        
         self.circle = circle
         self.startAngle = startAngle
         self.endAngle = endAngle
@@ -87,9 +87,9 @@ internal extension CGVector {
 }
 
 internal extension CGRect {
-
+    
     // get the center of rect (bounds or frame)
-    internal var center: CGPoint {
+    var center: CGPoint {
         get {
             let center = CGPoint(x: midX, y: midY)
             return center
@@ -114,7 +114,7 @@ internal class CircularSliderHelper {
     internal static func degrees(fromRadians value: CGFloat) -> CGFloat {
         return value * 180.0 / CGFloat(Double.pi)
     }
-
+    
     /**
      Returns the angle AÔB of an circle
 
@@ -176,12 +176,20 @@ internal class CircularSliderHelper {
      - returns: the value in the new interval
      */
     internal static func scaleValue(_ value: CGFloat, fromInterval source: Interval, toInterval destination: Interval) -> CGFloat {
-        let sourceRange = (source.max - source.min) / CGFloat(source.rounds)
-        let destinationRange = (destination.max - destination.min) / CGFloat(destination.rounds)
-        let scaledValue = source.min + (value - source.min).truncatingRemainder(dividingBy: sourceRange)
-        let newValue =  (((scaledValue - source.min) * destinationRange) / sourceRange) + destination.min
-
-        return  newValue
+        // If the value is equal to the min or the max no need to calculate
+        switch value {
+        case source.min:
+            return destination.min
+        case source.max:
+            return destination.max
+        default:
+            let sourceRange = (source.max - source.min) / CGFloat(source.rounds)
+            let destinationRange = (destination.max - destination.min) / CGFloat(destination.rounds)
+            let scaledValue = source.min + (value - source.min).truncatingRemainder(dividingBy: sourceRange)
+            let newValue =  (((scaledValue - source.min) * destinationRange) / sourceRange) + destination.min
+
+            return  newValue
+        }
     }
 
     /**
@@ -192,7 +200,7 @@ internal class CircularSliderHelper {
      the angle value is equal to π
 
      @see value(inInterval: fromAngle:)
-
+     
      - parameter aValue:      the original value
      - parameter oldIntreval: the original interval
 
@@ -223,16 +231,16 @@ internal class CircularSliderHelper {
 
         return value
     }
-
+    
     internal static func delta(in interval: Interval, for angle: CGFloat, oldValue: CGFloat) -> CGFloat {
         let angleIntreval = Interval(min: circleMinValue , max: circleMaxValue)
-
+        
         let oldAngle = scaleToAngle(value: oldValue, inInterval: interval)
         let deltaAngle = self.angle(from: oldAngle, to: angle)
-
+        
         return scaleValue(deltaAngle, fromInterval: angleIntreval, toInterval: interval)
     }
-
+    
     /**
      * Length (angular) of a shortest way between two angles.
      * It will be in range [-π/2, π/2], where sign means dir (+ for clockwise, - for counter clockwise).
@@ -242,7 +250,7 @@ internal class CircularSliderHelper {
         // Rotate right
         let offset = alpha >= halfValue ? circleMaxValue - alpha : -alpha
         let offsetBeta = beta + offset
-
+        
         if offsetBeta > halfValue {
             return offsetBeta - circleMaxValue
         }