space-ios/iOSClient/Utility/UIColor+adjust.swift

//
//  UIColor+adjust.swift
//  Nextcloud
//
//  Created by Marino Faggiana on 04/02/2020.
//  Copyright © 2020 Marino Faggiana. All rights reserved.
//

import Foundation

extension UIColor {

    @objc func lighter(by percentage: CGFloat = 30.0) -> UIColor? {
        return self.adjust(by: abs(percentage) )
    }

    @objc func darker(by percentage: CGFloat = 30.0) -> UIColor? {
        return self.adjust(by: -1 * abs(percentage) )
    }

    func adjust(by percentage: CGFloat = 30.0) -> UIColor? {
        var red: CGFloat = 0, green: CGFloat = 0, blue: CGFloat = 0, alpha: CGFloat = 0
        if self.getRed(&red, green: &green, blue: &blue, alpha: &alpha) {
            return UIColor(red: min(red + percentage/100, 1.0),
                           green: min(green + percentage/100, 1.0),
                           blue: min(blue + percentage/100, 1.0),
                           alpha: alpha)
        } else {
            return nil
        }
    }
    
    @objc func isTooLight() -> Bool {
        guard let components = cgColor.components, components.count > 2 else {return false}
        let brightness = ((components[0] * 299) + (components[1] * 587) + (components[2] * 114)) / 1000
        return (brightness > 0.95)
    }
    
    @objc func isTooDark() -> Bool {
        guard let components = cgColor.components, components.count > 2 else {return false}
        let brightness = ((components[0] * 299) + (components[1] * 587) + (components[2] * 114)) / 1000
        return (brightness < 0.05)
    }
}