ShadowLabelNode

ShadowLabelNode.swift

// based on objective-c code Erica Sadun:  https://github.com/erica/useful-things

import SpriteKit

fileprivate let shadowEffectNodeKey = "ShadowEffectNodeKey"

class ShadowLabelNode: SKLabelNode {
    var offset : CGPoint = CGPoint(x: 1, y: -1) {
        didSet { updateShadow() }
    }
    var shadowColor : UIColor = UIColor.darkGray.color(alpha: 0.8) {
        didSet { updateShadow() }
    }
    var blurRadius : CGFloat = 3 {
        didSet { updateShadow() }
    }
    
    private var hasObservers: Bool = false
    
    override init() {
        super.init()
        
        for keyPath in ["text", "fontName", "fontSize", "verticalAlignmentMode", "horizontalAlignmentMode", "fontColor"] {
            self.addObserver(self, forKeyPath: keyPath, options: NSKeyValueObservingOptions.new, context: nil)
        }
        
        self.updateShadow()
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    override init(fontNamed: String?) {
        super.init(fontNamed: fontNamed)
        
        for keyPath in ["text", "fontName", "fontSize", "verticalAlignmentMode", "horizontalAlignmentMode", "fontColor"] {
            self.addObserver(self, forKeyPath: keyPath, options: NSKeyValueObservingOptions.new, context: nil)
        }
        
        self.updateShadow()
    }
    
    private func makeEffectNode() -> SKEffectNode {
        let effectNode = SKEffectNode()
        effectNode.name = "ShadowEffectNodeKey"
        effectNode.shouldEnableEffects = true
        effectNode.zPosition = -1
        return effectNode
    }
    
    func updateShadow () {
        let effectNode = self.childNode(withName: shadowEffectNodeKey) as? SKEffectNode ?? makeEffectNode()
        
        let filter: CIFilter? = CIFilter(name: "CIGaussianBlur")
        filter?.setDefaults();
        filter?.setValue(blurRadius, forKey: "inputRadius")
        effectNode.filter = filter
        effectNode.removeAllChildren()
        
        // Duplicate and offset the label
        let labelNode = SKLabelNode(fontNamed: self.fontName)
        labelNode.text = self.text
        labelNode.fontSize = self.fontSize
        labelNode.verticalAlignmentMode = self.verticalAlignmentMode
        labelNode.horizontalAlignmentMode = self.horizontalAlignmentMode
        labelNode.fontColor = shadowColor
        labelNode.position = offset
        
        effectNode.addChild(labelNode)
        if effectNode.parent == nil {
            self.addChild(effectNode)
        }
    }
    
    override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
        self.updateShadow()
    }
    
}

extension ShadowLabelNode {
    
    // Removes all of the observers for the shadow node and the label itself.
    func removeLabel () {
        
        for keyPath in ["text", "fontName", "fontSize", "verticalAlignmentMode", "horizontalAlignmentMode", "fontColor"] {
            self.removeObserver(self, forKeyPath: keyPath);
            self.removeFromParent();
        }
        
    }
    
}