NetNewsWire/iOS/UIKit Extensions/UIImage-Extensions.swift

44 lines
896 B
Swift

//
// UIImage-Extensions.swift
// NetNewsWire
//
// Created by Maurice Parker on 9/29/19.
// Copyright © 2019 Ranchero Software. All rights reserved.
//
import UIKit
extension CGImage {
func isDark() -> Bool {
guard let imageData = self.dataProvider?.data else { return false }
guard let ptr = CFDataGetBytePtr(imageData) else { return false }
let length = CFDataGetLength(imageData)
var pixelCount = 0
var totalLuminance = 0.0
for i in stride(from: 0, to: length, by: 4) {
let r = ptr[i]
let g = ptr[i + 1]
let b = ptr[i + 2]
let luminance = (0.299 * Double(r) + 0.587 * Double(g) + 0.114 * Double(b))
totalLuminance += luminance
pixelCount += 1
}
let avgLuminance = totalLuminance / Double(pixelCount)
return avgLuminance < 37.5
}
}
extension UIImage {
func isDark() -> Bool {
return self.cgImage?.isDark() ?? false
}
}