Tusker/Tusker/Views/BaseEmojiLabel.swift

85 lines
3.2 KiB
Swift

//
// BaseEmojiLabel.swift
// Tusker
//
// Created by Shadowfacts on 10/18/20.
// Copyright © 2020 Shadowfacts. All rights reserved.
//
import UIKit
import Pachyderm
private let emojiRegex = try! NSRegularExpression(pattern: ":(\\w+):", options: [])
protocol BaseEmojiLabel: AnyObject {
var emojiIdentifier: String? { get set }
var emojiRequests: [ImageCache.Request] { get set }
var emojiFont: UIFont { get }
var emojiTextColor: UIColor { get }
}
extension BaseEmojiLabel {
func replaceEmojis(in string: String, emojis: [Emoji], identifier: String, completion: @escaping (NSAttributedString) -> Void) {
let matches = emojiRegex.matches(in: string, options: [], range: NSRange(location: 0, length: string.utf16.count))
guard !matches.isEmpty else {
completion(NSAttributedString(string: string))
return
}
let emojiImages = MultiThreadDictionary<String, UIImage>(name: "BaseEmojiLabel Emoji Images")
var foundEmojis = false
let group = DispatchGroup()
for emoji in emojis {
// only make requests for emojis that are present in the text to avoid making unnecessary network requests
guard matches.contains(where: { (match) in
let matchShortcode = (string as NSString).substring(with: match.range(at: 1))
return emoji.shortcode == matchShortcode
}) else {
continue
}
foundEmojis = true
group.enter()
let request = ImageCache.emojis.get(emoji.url) { (_, image) in
defer { group.leave() }
guard let image = image,
let transformedImage = ImageGrayscalifier.convertIfNecessary(url: emoji.url, image: image) else {
return
}
emojiImages[emoji.shortcode] = transformedImage
}
if let request = request {
emojiRequests.append(request)
}
}
guard foundEmojis else {
completion(NSAttributedString(string: string))
return
}
group.notify(queue: .main) { [weak self] in
// if e.g. the account changes before all emojis are loaded, don't bother trying to set them
guard let self = self, self.emojiIdentifier == identifier else { return }
let mutAttrString = NSMutableAttributedString(string: string)
// replaces the emojis starting from the end of the string as to not alter the indices of preceeding emojis
for match in matches.reversed() {
let shortcode = (string as NSString).substring(with: match.range(at: 1))
guard let emojiImage = emojiImages[shortcode] else {
continue
}
let attachment = NSTextAttachment(emojiImage: emojiImage, in: self.emojiFont, with: self.emojiTextColor)
let attachmentStr = NSAttributedString(attachment: attachment)
mutAttrString.replaceCharacters(in: match.range, with: attachmentStr)
}
completion(mutAttrString)
}
}
}