Revision control
Copy as Markdown
// 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: Sendable {
/// 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
}
final class DefaultLetterImageGenerator: LetterImageGenerator, @unchecked Sendable {
private let logger: Logger
private let themeManagerProvider: () -> ThemeManager
init(themeManager: @autoclosure @escaping () -> ThemeManager = AppContainer.shared.resolve(),
logger: Logger = DefaultLogger.shared) {
self.themeManagerProvider = themeManager
self.logger = logger
}
@MainActor
func generateLetterImage(siteString: String) async throws -> UIImage {
let capitalizedLetter = try generateLetter(fromSiteString: siteString)
let colorSet = themeManagerProvider().windowNonspecificTheme().colors.faviconLetterColorSet
let index = colorIndex(forSite: siteString, colorSet: colorSet)
let image = generateImage(fromLetter: capitalizedLetter,
color: colorSet.backgroundColors[index],
letterColor: colorSet.letterColors[index])
return image
}
internal func generateLetter(fromSiteString siteString: String) throws -> String {
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
}
return letter.uppercased()
}
@MainActor
internal func generateImage(fromLetter letter: String, color: UIColor, letterColor: UIColor = .white) -> 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 = letterColor
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
}
internal func colorIndex(forSite siteString: String, colorSet: FaviconLetterColorSet) -> Int {
return abs(stableHash(siteString)) % colorSet.backgroundColors.count
}
internal func generateBackgroundColor(forSite siteString: String, colorSet: FaviconLetterColorSet) -> UIColor {
return colorSet.backgroundColors[colorIndex(forSite: siteString, colorSet: colorSet)]
}
private func stableHash(_ str: String) -> Int {
let unicodeScalars = str.unicodeScalars.map { $0.value }
return unicodeScalars.reduce(5381) {
($0 << 5) &+ $0 &+ Int($1)
}
}
}