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Display/NavigationBackButtonNode.swift

@@ -0,0 +1,143 @@
+import UIKit
+import AsyncDisplayKit
+
+public class NavigationBackButtonNode: ASControlNode {
+    private func fontForCurrentState() -> UIFont {
+        return UIFont.systemFontOfSize(17.0)
+    }
+    
+    private func attributesForCurrentState() -> [String : AnyObject] {
+        return [
+            NSFontAttributeName: self.fontForCurrentState(),
+            NSForegroundColorAttributeName: self.enabled ? UIColor.blueColor() : UIColor.grayColor()
+        ]
+    }
+    
+    var suspendLayout = false
+    
+    let arrow: ASDisplayNode
+    let label: ASTextNode
+    
+    private let arrowSpacing: CGFloat = 4.0
+    
+    private var _text: String = ""
+    var text: String {
+        get {
+            return self._text
+        }
+        set(value) {
+            self._text = value
+            self.label.attributedString = NSAttributedString(string: text, attributes: self.attributesForCurrentState())
+            self.invalidateCalculatedLayout()
+        }
+    }
+    
+    private var touchCount = 0
+    var pressed: () -> () = {}
+    
+    override init() {
+        self.arrow = ASDisplayNode()
+        self.label = ASTextNode()
+        
+        super.init()
+        
+        self.userInteractionEnabled = true
+        self.exclusiveTouch = true
+        self.hitTestSlop = UIEdgeInsets(top: -16.0, left: -10.0, bottom: -16.0, right: -10.0)
+        self.displaysAsynchronously = false
+        
+        self.arrow.displaysAsynchronously = false
+        self.label.displaysAsynchronously = false
+        
+        self.addSubnode(self.arrow)
+        let arrowImage = UIImage(named: "NavigationBackArrowLight", inBundle: NSBundle(forClass: NavigationBackButtonNode.self), compatibleWithTraitCollection: nil)
+        self.arrow.contents = arrowImage?.CGImage
+        self.arrow.frame = CGRect(origin: CGPoint(), size: arrowImage?.size ?? CGSize())
+        
+        self.addSubnode(self.label)
+    }
+    
+    public override func calculateSizeThatFits(constrainedSize: CGSize) -> CGSize {
+        self.label.measure(CGSize(width: max(0.0, constrainedSize.width - self.arrow.frame.size.width - self.arrowSpacing), height: constrainedSize.height))
+        
+        return CGSize(width: self.arrow.frame.size.width + self.arrowSpacing + self.label.calculatedSize.width, height: max(self.arrow.frame.size.height, self.label.calculatedSize.height))
+    }
+    
+    var labelFrame: CGRect {
+        get {
+            return CGRect(x: self.arrow.frame.size.width + self.arrowSpacing, y: floor((self.frame.size.height - self.label.calculatedSize.height) / 2.0), width: self.label.calculatedSize.width, height: self.label.calculatedSize.height)
+        }
+    }
+    
+    public override func layout() {
+        super.layout()
+        
+        if self.suspendLayout {
+            return
+        }
+        
+        self.arrow.frame = CGRect(x: 0.0, y: floor((self.frame.size.height - arrow.frame.size.height) / 2.0), width: self.arrow.frame.size.width, height: self.arrow.frame.size.height)
+        
+        self.label.frame = self.labelFrame
+    }
+    
+    private func touchInsideApparentBounds(touch: UITouch) -> Bool {
+        var apparentBounds = self.bounds
+        let hitTestSlop = self.hitTestSlop
+        apparentBounds.origin.x += hitTestSlop.left
+        apparentBounds.size.width -= hitTestSlop.left + hitTestSlop.right
+        apparentBounds.origin.y += hitTestSlop.top
+        apparentBounds.size.height -= hitTestSlop.top + hitTestSlop.bottom
+        
+        return CGRectContainsPoint(apparentBounds, touch.locationInView(self.view))
+    }
+    
+    public override func touchesBegan(touches: Set<NSObject>!, withEvent event: UIEvent!) {
+        super.touchesBegan(touches, withEvent: event)
+        self.touchCount += touches.count
+        self.updateHighlightedState(true, animated: false)
+    }
+    
+    public override func touchesMoved(touches: Set<NSObject>!, withEvent event: UIEvent!) {
+        super.touchesMoved(touches, withEvent: event)
+        
+        self.updateHighlightedState(self.touchInsideApparentBounds(touches.first as! UITouch), animated: true)
+    }
+    
+    public override func touchesEnded(touches: Set<NSObject>!, withEvent event: UIEvent!) {
+        super.touchesEnded(touches, withEvent: event)
+        self.updateHighlightedState(false, animated: false)
+        
+        let previousTouchCount = self.touchCount
+        self.touchCount = max(0, self.touchCount - touches.count)
+        
+        if previousTouchCount != 0 && self.touchCount == 0 && self.enabled && self.touchInsideApparentBounds(touches.first as! UITouch) {
+            self.pressed()
+        }
+    }
+    
+    public override func touchesCancelled(touches: Set<NSObject>!, withEvent event: UIEvent!) {
+        super.touchesCancelled(touches, withEvent: event)
+        
+        self.touchCount = max(0, self.touchCount - touches.count)
+        self.updateHighlightedState(false, animated: false)
+    }
+    
+    private var _highlighted = false
+    private func updateHighlightedState(highlighted: Bool, animated: Bool) {
+        if _highlighted != highlighted {
+            _highlighted = highlighted
+            
+            let alpha: CGFloat = !enabled ? 1.0 : (highlighted ? 0.4 : 1.0)
+            
+            if animated {
+                UIView.animateWithDuration(0.3, delay: 0.0, options: UIViewAnimationOptions.BeginFromCurrentState, animations: { () -> Void in
+                    self.alpha = alpha
+                    }, completion: nil)
+            }
+            else {
+                self.alpha = alpha
+            }
+        }
+    }
+}