FaceView.swift

import UIKit

@IBDesignable
class FaceView: UIView {
    
    //Don't type infer
    @IBInspectable
    var scale: CGFloat = 0.9
    
    @IBInspectable
    var eyesOpen: Bool = true
    
    @IBInspectable
    var mouthCurvature: Double = 1.0
    
    @IBInspectable
    var lineWidth: CGFloat = 5.0
    
    @IBInspectable
    var color: UIColor = UIColor.blue
    
    private var skullRadius:CGFloat {
        return min(bounds.size.width, bounds.size.height) / 2 * scale
    }
    
    private var skullCenter: CGPoint{
        get {
            return CGPoint(x: bounds.midX, y: bounds.midY)
        }
        
    }
    
    private enum Eye {
        case left
        case right
    }
    
    private func pathForEye(_ eye: Eye) -> UIBezierPath {
        func centerOfEye(_ eye: Eye) -> CGPoint {
            let eyeOffset = skullRadius / Ratios.skullRadiusToEyeOffset
            var eyeCenter = skullCenter
            eyeCenter.y -= eyeOffset
            eyeCenter.x += ((eye == .left) ? -1 : 1) * eyeOffset
            return eyeCenter
        }
        
        let eyeRadius = skullRadius / Ratios.skullRadiusToEyeRadius
        let eyeCenter = centerOfEye(eye)
        
        let path: UIBezierPath
        if eyesOpen {
            path = UIBezierPath(arcCenter: eyeCenter, radius: eyeRadius, startAngle: 0, endAngle: CGFloat.pi * 2, clockwise: true)
        } else {
            path = UIBezierPath()
            path.move(to: CGPoint(x: eyeCenter.x - eyeRadius, y: eyeCenter.y))
            path.addLine(to: CGPoint(x: eyeCenter.x + eyeRadius, y: eyeCenter.y))
        }
        
        path.lineWidth = lineWidth //5.0
        return path
    }
    
    private func pathForMouth() -> UIBezierPath {
        let mouthWidth = skullRadius / Ratios.skullRadiusToMouthWidth
        let mouthHeight = skullRadius / Ratios.skullRadiusToMouthHeight
        let mouthOffset = skullRadius / Ratios.skullRadiusToEyeOffset
        
        let mouthRect = CGRect(
            x: skullCenter.x - mouthWidth / 2,
            y: skullCenter.y + mouthOffset,
            width: mouthWidth,
            height: mouthHeight)
        
        let smileOffset = CGFloat(max(-1, min(mouthCurvature, 1))) * mouthRect.height
        
        let start = CGPoint(x: mouthRect.minX, y: mouthRect.midY)
        let end = CGPoint(x: mouthRect.maxX, y: mouthRect.midY)
        
        let cp1 = CGPoint(x: start.x + mouthRect.width / 3, y: start.y + smileOffset)
        let cp2 = CGPoint(x: end.x - mouthRect.width / 3, y: start.y + smileOffset)
        
        //let path = UIBezierPath(rect: mouthRect)
        let path = UIBezierPath()
        path.move(to: start)
        path.addCurve(to: end, controlPoint1: cp1, controlPoint2: cp2)
        path.lineWidth = lineWidth //5.0
        return path
    }
    
    
    private func pathForSkull() -> UIBezierPath {
        let path = UIBezierPath(arcCenter: skullCenter, radius: skullRadius, startAngle: 0, endAngle: 2 * CGFloat.pi, clockwise: false)
        path.lineWidth = lineWidth //5.0
        return path
    }
    
    override func draw(_ rect: CGRect) {
        //let skullRadius = min(bounds.size.width, bounds.size.height) / 2 * 0.9
        //let skullCenter = convert(center, from: superview)
        //let skullCenter = CGPoint(x: bounds.midX, y: bounds.midY)
        //let path = UIBezierPath(arcCenter: skullCenter, radius: skullRadius, startAngle: 0, endAngle: 2 * CGFloat.pi, clockwise: false)
        //path.lineWidth = 5.0
        //UIColor.blue.set()
        color.set()
        //path.stroke()
        pathForSkull().stroke()
        pathForEye(.left).stroke()
        pathForEye(.right).stroke()
        pathForMouth().stroke()
    }
    
    private struct Ratios {
        static let skullRadiusToEyeOffset: CGFloat = 3
        static let skullRadiusToEyeRadius: CGFloat = 10
        static let skullRadiusToMouthWidth: CGFloat = 1
        static let skullRadiusToMouthHeight: CGFloat = 3
        static let skullRadiusToMouthOffset: CGFloat = 3
    }

}