Impressia/Vernissage/Modifiers/AnimatePlaceholderModifier.swift

//
//  https://mczachurski.dev
//  Copyright © 2023 Marcin Czachurski and the repository contributors.
//  Licensed under the MIT License.
//
    
import SwiftUI

struct AnimatePlaceholderModifier: AnimatableModifier {
    @Binding var isLoading: Bool

    @State private var isAnim: Bool = false
    private var center = (UIScreen.main.bounds.width / 2) + 110
    // private let animation: Animation = .linear(duration: 1.5)
    private let animation: Animation = .easeOut(duration: 1)

    init(isLoading: Binding<Bool>) {
        self._isLoading = isLoading
    }

    func body(content: Content) -> some View {
        content.overlay(animView.mask(content))
    }

    var animView: some View {
        LinearGradient(
            gradient: .init(colors: [.black, .black.opacity(0.6), .black.opacity(0.3), .clear]),
            startPoint: .leading,
            endPoint: isAnim ? .trailing : .leading)
        .animation(isLoading ? animation.repeatForever(autoreverses: false) : nil, value: isAnim)
        .onAppear {
            guard isLoading else { return }
            isAnim.toggle()
        }
        .onChange(of: isLoading) { _ in
            isAnim.toggle()
        }
    }
}

extension View {
    func animatePlaceholder(isLoading: Binding<Bool>) -> some View {
        self.modifier(AnimatePlaceholderModifier(isLoading: isLoading))
    }
}