Add strokeStart / End property

Author: kentya6

Example/Base.lproj/Main.storyboard

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="14109" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" colorMatched="YES" initialViewController="BYZ-38-t0r">
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="14113" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" colorMatched="YES" initialViewController="BYZ-38-t0r">
     <device id="retina4_7" orientation="portrait">
         <adaptation id="fullscreen"/>
     </device>

Example/ViewController.swift

@@ -39,7 +39,8 @@ class ViewController: UIViewController {
     private func configureHalfCircularProgress() {
         halfCircularProgress = KYCircularProgress(frame: CGRect(x: 0, y: 0, width: view.frame.width, height: view.frame.height/2), showGuide: true)
         let center = CGPoint(x: view.frame.width / 2, y: view.frame.height / 4)
-        halfCircularProgress.path = UIBezierPath(arcCenter: center, radius: CGFloat((halfCircularProgress.frame).width/3), startAngle: CGFloat(Double.pi), endAngle: CGFloat(0.0), clockwise: true)
+        halfCircularProgress.path = UIBezierPath(arcCenter: center, radius: CGFloat((halfCircularProgress.frame).width/3), startAngle: 0, endAngle: CGFloat(Double.pi * 2), clockwise: true)
+        halfCircularProgress.strokeStart = 0.5
         halfCircularProgress.colors = [UIColor(rgba: 0xA6E39DAA), UIColor(rgba: 0xAEC1E3AA), UIColor(rgba: 0xAEC1E3AA), UIColor(rgba: 0xF3C0ABAA)]
         halfCircularProgress.guideColor = UIColor(red: 0.1, green: 0.1, blue: 0.1, alpha: 0.4)
 

Source/KYCircularProgress.swift

@@ -31,8 +31,8 @@ open class KYCircularProgress: UIView {
      */
     @IBInspectable open var progress: Double = 0.0 {
         didSet {
-            let clipProgress = max( min(progress, Double(1.0)), Double(0.0) )
-            progressView.update(progress: clipProgress)
+            let clipProgress = max( min( progress, 1.0), 0.0 )
+            progressView.update(progress: normalize(progress: clipProgress))
 
             progressChanged?(clipProgress, self)
             delegate?.progressChanged(progress: clipProgress, circularProgress: self)
@@ -105,22 +105,22 @@ open class KYCircularProgress: UIView {
     }
 
     /**
-     Progress start angle.
+     Progress start offset. (0.0 - 1.0)
      */
-    open var startAngle: Double = 0.0 {
+    @IBInspectable open var strokeStart: Double = 0.0 {
         didSet {
-            progressView.startAngle = startAngle
-            guideView.startAngle = startAngle
+            progressView.shapeLayer.strokeStart = CGFloat(max( min(strokeStart, 1.0), 0.0 ))
+            guideView.shapeLayer.strokeStart = CGFloat(max( min(strokeStart, 1.0), 0.0 ))
         }
     }
 
     /**
-     Progress end angle.
+     Progress end offset. (0.0 - 1.0)
      */
-    open var endAngle: Double = 0.0 {
+    @IBInspectable open var strokeEnd: Double = 1.0 {
         didSet {
-            progressView.endAngle = endAngle
-            guideView.endAngle = endAngle
+            progressView.shapeLayer.strokeEnd = CGFloat(max( min(strokeEnd, 1.0), 0.0 ))
+            guideView.shapeLayer.strokeEnd = CGFloat(max( min(strokeEnd, 1.0), 0.0 ))
         }
     }
 
@@ -175,7 +175,7 @@ open class KYCircularProgress: UIView {
         self.progressView.radius = self.radius
         guideView.shapeLayer.path = self.progressView.shapeLayer.path
         guideView.shapeLayer.strokeColor = self.tintColor.cgColor
-        guideView.update(progress: 1.0)
+        guideView.update(progress: normalize(progress: 1.0))
         return guideView
     }()
 
@@ -234,8 +234,8 @@ open class KYCircularProgress: UIView {
     }
 
     public func set(progress: Double, duration: Double) {
-        let clipProgress = max( min(progress, Double(1.0)), Double(0.0) )
-        progressView.update(progress: clipProgress, duration: duration)
+        let clipProgress = max( min(progress, 1.0), 0.0 )
+        progressView.update(progress: normalize(progress: clipProgress), duration: duration)
 
         progressChanged?(clipProgress, self)
         delegate?.progressChanged(progress: clipProgress, circularProgress: self)
@@ -248,6 +248,10 @@ open class KYCircularProgress: UIView {
         }
     }
 
+    private func normalize(progress: Double) -> CGFloat {
+        return CGFloat(strokeStart + progress * (strokeEnd - strokeStart))
+    }
+    
     override open func layoutSubviews() {
         super.layoutSubviews()
 
@@ -267,8 +271,6 @@ public protocol KYCircularProgressDelegate {
 
 // MARK: - KYCircularShapeView
 class KYCircularShapeView: UIView {
-    var startAngle = 0.0
-    var endAngle = 0.0
     var radius = 0.0
     var scale: (x: CGFloat, y: CGFloat) = (1.0, 1.0)
 
@@ -292,27 +294,24 @@ class KYCircularShapeView: UIView {
     override func layoutSubviews() {
         super.layoutSubviews()
 
-        if startAngle == endAngle {
-            endAngle = startAngle + (Double.pi * 2)
-        }
         shapeLayer.path = shapeLayer.path ?? layoutPath().cgPath
         var affineScale = CGAffineTransform(scaleX: scale.x, y: scale.y)
         shapeLayer.path = shapeLayer.path?.copy(using: &affineScale)
     }
 
     private func layoutPath() -> UIBezierPath {
         let halfWidth = CGFloat(frame.width / 2.0)
-        return UIBezierPath(arcCenter: CGPoint(x: halfWidth, y: halfWidth), radius: (frame.width - CGFloat(radius)) / 2, startAngle: CGFloat(startAngle), endAngle: CGFloat(endAngle), clockwise: true)
+        return UIBezierPath(arcCenter: CGPoint(x: halfWidth, y: halfWidth), radius: (frame.width - CGFloat(radius)) / 2, startAngle: 0, endAngle: CGFloat(Double.pi * 2), clockwise: true)
     }
 
-    fileprivate func update(progress: Double) {
+    fileprivate func update(progress: CGFloat) {
         CATransaction.begin()
         CATransaction.setValue(kCFBooleanTrue, forKey: kCATransactionDisableActions)
-        shapeLayer.strokeEnd = CGFloat(progress)
+        shapeLayer.strokeEnd = progress
         CATransaction.commit()
     }
 
-    fileprivate func update(progress: Double, duration: Double) {
+    fileprivate func update(progress: CGFloat, duration: Double) {
         CATransaction.begin()
         let animation = CABasicAnimation(keyPath: "strokeEnd")
         animation.duration = duration
@@ -321,7 +320,7 @@ class KYCircularShapeView: UIView {
         animation.toValue = progress
         shapeLayer.add(animation, forKey: "animateStrokeEnd")
         CATransaction.commit()
-        shapeLayer.strokeEnd = CGFloat(progress)
+        shapeLayer.strokeEnd = progress
     }
 }