easeinbounce.swift

//

import SwiftUI
import Observation

// easeInBounce
//
// https://easings.net
// https://gist.github.com/girish3/11167208

struct MyLinearAnimation: CustomAnimation {
    var duration: TimeInterval

    func animate<V>(value: V, time: TimeInterval, context: inout AnimationContext<V>) -> V? where V : VectorArithmetic {


        if time > duration { return nil }
        let t = time/duration
        var progress: Double
        if t < (1/2.75) {
            progress = 7.5625 * t * t
        } else if t < (2/2.75) {
            let t2 = t-(1.5/2.75)
            progress = 7.5625 * t2 * t2 + 0.75
        } else if t < (2.5/2.75) {
            let t2 = t - (2.25/2.75)
            progress = (7.5625 * t2 * t2 + 0.9375)
        } else {
            let t2 = t - (2.625/2.75)
            progress = 1 * (7.5625 * t2 * t2 + 0.984375)
        }
        print(progress)

        let result = value.scaled(by: progress)
        return result
    }
}

struct ContentView: View {
    @State var active = false
    var body: some View {
        Color.red
            .frame(width: 50, height: active ? 100 : 50)
            .frame(maxHeight: .infinity, alignment: active ? .top : .bottom)
            .contentShape(.rect)
            .onTapGesture {
                withAnimation(.init(MyLinearAnimation(duration: 2))) {
                    active.toggle()
                } completion: {
                    print("Completed")
                }
            }

    }
}

#Preview {
    ContentView()
}