Native Source code for CodeSlicing episode on Animated Pac-Man (requires PureSwiftUI v2.1.0+)

AnimatedPacManDemoNative.swift

//
//  AnimatedPacManDemoNative.swift
//
//  Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the "Software"), to deal
//  in the Software without restriction, including without limitation the rights
//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
//  of the Software, and to permit persons to whom the Software is furnished to do so,
//  subject to the following conditions:
//
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
//  INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
//  PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
//  COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
//  AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
//  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
//  Created by Adam Fordyce on 23/04/2021.
//  Copyright © 2020 Adam Fordyce. All rights reserved.
//

import SwiftUI

private let pacManDiameter: CGFloat = 100
private let maxOffset = UIScreen.main.bounds.width * 0.5 + pacManDiameter * 0.5

struct AnimatedPacManDemoNative: View {
    
    @State private var animatingMouth = false
    @State private var animatingPosition = false
    
    var body: some View {
        let xOffset = maxOffset * (animatingPosition ? 1 : -1)
        PacMan(animatingMouth: animatingMouth)
            .fill(Color.yellow, style: .init(eoFill: true))
            .frame(width: pacManDiameter, height: pacManDiameter)
            .offset(x: xOffset)
            .onAppear {
                withAnimation(Animation.easeInOut(duration: 0.2).repeatForever()) {
                    animatingMouth = true
                }
                withAnimation(Animation.linear(duration: 3).repeatForever(autoreverses: false)) {
                    animatingPosition = true
                }
            }
    }
}

private struct PacMan: Shape {
    
    var animatableData: CGFloat
    
    init(animatingMouth: Bool) {
        animatableData = animatingMouth ? 1 : 0
    }
    
    func path(in rect: CGRect) -> Path {
        var path = Path()
        
        // mouth
        let rectCenter = CGPoint(x: rect.midX, y: rect.midY)
        
        path.move(to: rectCenter)

        let startAngleMax = Angle.degrees(0)
        let startAngleMin = Angle.degrees(45)
        
        let startAngleDeltaDegrees = startAngleMax.degrees - startAngleMin.degrees
        let startAngleDegrees = startAngleMin.degrees + (startAngleDeltaDegrees * Double(animatableData))

        let endAngleMax = Angle.degrees(-0.001)
        let endAngleMin = Angle.degrees(-45)
        
        let endAngleDeltaDegrees = endAngleMax.degrees - endAngleMin.degrees
        let endAngleDegrees = endAngleMin.degrees + (endAngleDeltaDegrees * Double(animatableData))

        let startAngle = Angle.degrees(startAngleDegrees)
        let endAngle = Angle.degrees(endAngleDegrees)

        path.addArc(center: rectCenter, radius: rect.width * 0.5, startAngle: startAngle, endAngle: endAngle, clockwise: false)
                 
        // eye
        let eyePosition = CGPoint(x: rect.minX + rect.width * 0.65,
                                  y: rect.minY + rect.height * 0.2)
        
        let eyeRadius = rect.width * 0.05
        let eyeDiameter = eyeRadius * 2
        let eyeOrigin = CGPoint(x: eyePosition.x - eyeRadius, y: eyePosition.y - eyeRadius)
        let eyeRect = CGRect(origin: eyeOrigin, size: CGSize(width: eyeDiameter, height: eyeDiameter))
        
        path.addEllipse(in: eyeRect)
        
        return path
    }
}

struct AnimatedPacManDemoNative_Previews: PreviewProvider {
    struct AnimatedPacManDemoNative_Harness: View {
        
        var body: some View {
            AnimatedPacManDemoNative()
                .frame(maxWidth: .infinity, maxHeight: .infinity)
                .foregroundColor(.white)
                .background(Color(white: 0.1))
                .ignoresSafeArea()
        }
    }
    
    static var previews: some View {
        AnimatedPacManDemoNative_Harness()
            .previewDevice("iPhone 12 Pro Max")
            .previewDisplayName("iPhone 12 Pro Max")
    }
}