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// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
import UIKit
import Common
/// Generate a default letter image from the domain name
protocol LetterImageGenerator {
/// Generates a letter image based on the first character in the domain name
/// Runs main thread due to UILabel.initWithFrame(:)
/// - Parameter domain: The string domain name
/// - Returns: The generated letter image
@MainActor
func generateLetterImage(siteString: String) async throws -> UIImage
}
class DefaultLetterImageGenerator: LetterImageGenerator {
private var logger: Logger
init(logger: Logger = DefaultLogger.shared) {
self.logger = logger
}
@MainActor
func generateLetterImage(siteString: String) async throws -> UIImage {
guard let letter: Character = siteString.first else {
logger.log("No letter found for site, which should never happen",
level: .warning,
category: .images)
throw SiteImageError.noLetterImage
}
let capitalizedLetter = letter.uppercased()
let color = generateBackgroundColor(forSite: siteString)
let image = generateImage(fromLetter: capitalizedLetter,
color: color)
return image
}
func generateImage(fromLetter letter: String, color: UIColor) -> UIImage {
var image = UIImage()
let label = UILabel(frame: CGRect(x: 0, y: 0, width: 60, height: 60))
label.text = letter
label.textAlignment = .center
label.font = UIFont.systemFont(ofSize: 40, weight: UIFont.Weight.medium)
label.textColor = .white
UIGraphicsBeginImageContextWithOptions(label.bounds.size, false, 0.0)
let rect = CGRect(origin: .zero, size: label.bounds.size)
let context = UIGraphicsGetCurrentContext()!
context.setFillColor(color.cgColor)
context.fill(rect)
label.layer.render(in: context)
image = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
return image
}
private func generateBackgroundColor(forSite siteString: String) -> UIColor {
let index = abs(stableHash(siteString)) % (defaultBackgroundColors.count - 1)
let colorHex = defaultBackgroundColors[index]
return UIColor(colorString: colorHex)
}
private func stableHash(_ str: String) -> Int {
let unicodeScalars = str.unicodeScalars.map { $0.value }
return unicodeScalars.reduce(5381) {
($0 << 5) &+ $0 &+ Int($1)
}
}
// Used as background color for generated letters
private let defaultBackgroundColors = ["2e761a",
"399320",
"40a624",
"57bd35",
"70cf5b",
"90e07f",
"b1eea5",
"881606",
"aa1b08",
"c21f09",
"d92215",
"ee4b36",
"f67964",
"ffa792",
"025295",
"0568ba",
"0675d3",
"0996f8",
"2ea3ff",
"61b4ff",
"95cdff",
"00736f",
"01908b",
"01a39d",
"01bdad",
"27d9d2",
"58e7e6",
"89f4f5",
"c84510",
"e35b0f",
"f77100",
"ff9216",
"ffad2e",
"ffc446",
"ffdf81",
"911a2e",
"b7223b",
"cf2743",
"ea385e",
"fa526e",
"ff7a8d",
"ffa7b3" ]
}
// MARK: - UIColor extension
extension UIColor {
convenience init(rgb: Int) {
self.init(
red: CGFloat((rgb & 0xFF0000) >> 16) / 255.0,
green: CGFloat((rgb & 0x00FF00) >> 8) / 255.0,
blue: CGFloat((rgb & 0x0000FF) >> 0) / 255.0,
alpha: 1)
}
convenience init(colorString: String) {
var colorInt: UInt64 = 0
Scanner(string: colorString).scanHexInt64(&colorInt)
self.init(rgb: (Int) (colorInt))
}
}