yongxu-app-ios/fiveConstant/components/LoaderUI/BallScaleRippleMultiple.swift

//
//  BallScaleRippleMultiple.swift
//  LoaderUI
//
//  Created by Vinh Nguyen on 5/18/20.
//  Copyright © 2020 Vinh Nguyen. All rights reserved.
//

import SwiftUI

public struct BallScaleRippleMultiple: View {
    private let beginTimes = [0, 0.2, 0.4]
    private let duration = 1.25
    private let timingFunction = TimingFunction.timingCurve(c0x: 0.21, c0y: 0.53, c1x: 0.56, c1y: 0.8)
    private let keyTimes = [0, 0.7, 1]
    private let scaleValues: [CGFloat] = [0.1, 1, 1]
    private let opacityValues = [1, 0.7, 0]
    
    public var body: some View {
        GeometryReader(content: self.render)
    }

    public init() { }
    
    func render(geometry: GeometryProxy) -> some View {
        let dimension = min(geometry.size.width, geometry.size.height)
        let timingFunctions = Array(repeating: timingFunction, count: keyTimes.count - 1)
        
        return
            ZStack {
                ForEach(0..<3, id: \.self) { index in
                    KeyframeAnimationController(beginTime: self.beginTimes[index],
                                                duration: self.duration,
                                                timingFunctions: timingFunctions,
                                                keyTimes: self.keyTimes) {
                                                    Ring()
                                                        .scaleEffect(self.scaleValues[$0])
                                                        .opacity(self.opacityValues[$0])
                    }
                }
                
            }
            .frame(width: dimension, height: dimension, alignment: .center)
    }
}

struct BallScaleRippleMultiple_Previews: PreviewProvider {
    static var previews: some View {
        BallScaleRippleMultiple()
    }
}