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|
//
// SpinnerActivityIndicatorView.swift
// MullvadVPN
//
// Created by pronebird on 15/05/2019.
// Copyright © 2019 Mullvad VPN AB. All rights reserved.
//
import UIKit
private let kRotationAnimationKey = "rotation"
private let kAnimationDuration = 0.6
class SpinnerActivityIndicatorView: UIView {
enum Style {
case small, medium, large
var intrinsicSize: CGSize {
switch self {
case .small:
return .init(width: 16, height: 16)
case .medium:
return .init(width: 20, height: 20)
case .large:
return .init(width: 48, height: 48)
}
}
var thickness: CGFloat {
switch self {
case .small, .medium:
return 2
case .large:
return 6
}
}
}
/// Thickness of the front and back circles
var thickness: CGFloat = 6 {
didSet {
setLayersThickness()
}
}
/// The back circle color
var backCircleColor = UIColor.white.withAlphaComponent(0.2) {
didSet {
setBackCircleLayerColor()
}
}
/// The front circle color
var frontCircleColor: UIColor? {
didSet {
setFrontCircleLayerColor()
}
}
private(set) var isAnimating = false
private(set) var style = Style.large
fileprivate let frontCircle = CAShapeLayer()
fileprivate let backCircle = CAShapeLayer()
fileprivate var startTime = CFTimeInterval(0)
fileprivate var stopTime = CFTimeInterval(0)
override var intrinsicContentSize: CGSize {
return style.intrinsicSize
}
convenience init(style: Style) {
self.init(frame: .init(origin: .zero, size: style.intrinsicSize))
self.style = style
self.thickness = style.thickness
commonInit()
}
override init(frame: CGRect) {
super.init(frame: frame)
commonInit()
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
deinit {
unregisterFromAppStateNotifications()
}
override func layoutSublayers(of layer: CALayer) {
super.layoutSublayers(of: layer)
setupBezierPaths()
}
override func didMoveToWindow() {
super.didMoveToWindow()
if window != nil {
restartAnimationIfNeeded()
}
}
override func tintColorDidChange() {
super.tintColorDidChange()
setFrontCircleLayerColor()
}
func startAnimating() {
guard !isAnimating else { return }
isAnimating = true
isHidden = false
addAnimation()
}
func stopAnimating() {
guard isAnimating else { return }
isAnimating = false
isHidden = true
removeAnimation()
}
// MARK: - Private
private func commonInit() {
registerForAppStateNotifications()
isHidden = true
backgroundColor = UIColor.clear
backCircle.fillColor = UIColor.clear.cgColor
frontCircle.fillColor = UIColor.clear.cgColor
frontCircle.lineCap = .round
setBackCircleLayerColor()
setFrontCircleLayerColor()
setLayersThickness()
layer.addSublayer(backCircle)
layer.addSublayer(frontCircle)
}
private func setLayersThickness() {
backCircle.lineWidth = thickness
frontCircle.lineWidth = thickness
}
private func setBackCircleLayerColor() {
backCircle.strokeColor = backCircleColor.cgColor
}
private func setFrontCircleLayerColor() {
frontCircle.strokeColor = frontCircleColor?.cgColor ?? tintColor.cgColor
}
private func addAnimation() {
let timeOffset = stopTime - startTime
let anim = animation()
anim.timeOffset = timeOffset
layer.add(anim, forKey: kRotationAnimationKey)
startTime = layer.convertTime(CACurrentMediaTime(), from: nil) - timeOffset
}
private func removeAnimation() {
layer.removeAnimation(forKey: kRotationAnimationKey)
stopTime = layer.convertTime(CACurrentMediaTime(), from: nil)
}
@objc private func restartAnimationIfNeeded() {
let anim = layer.animation(forKey: kRotationAnimationKey)
if isAnimating && anim == nil {
removeAnimation()
addAnimation()
}
}
private func registerForAppStateNotifications() {
NotificationCenter.default.addObserver(self, selector: #selector(restartAnimationIfNeeded), name: UIApplication.willEnterForegroundNotification, object: nil)
}
private func unregisterFromAppStateNotifications() {
NotificationCenter.default.removeObserver(self)
}
private func animation() -> CABasicAnimation {
let animation = CABasicAnimation(keyPath: "transform.rotation")
animation.toValue = NSNumber(value: Double.pi * 2)
animation.duration = kAnimationDuration
animation.repeatCount = Float.infinity
animation.timingFunction = CAMediaTimingFunction(name: .linear)
return animation
}
private func setupBezierPaths() {
let center = CGPoint(x: bounds.size.width * 0.5, y: bounds.size.height * 0.5)
let radius = bounds.size.width * 0.5 - thickness
let closedRingPath = UIBezierPath(arcCenter: center, radius: radius, startAngle: 0, endAngle: CGFloat.pi * 2, clockwise: true)
let openRingPath = UIBezierPath(arcCenter: center, radius: radius, startAngle: 0, endAngle: CGFloat.pi * 1.5, clockwise: true)
backCircle.path = closedRingPath.cgPath
frontCircle.path = openRingPath.cgPath
}
}
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