56 lines
2.0 KiB
Swift
56 lines
2.0 KiB
Swift
@preconcurrency import SDWebImage
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import ExpoModulesCore
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class ThumbhashLoader: NSObject, SDImageLoader {
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typealias ImageLoaderCompletedBlock = @Sendable (UIImage?, Data?, (any Error)?, Bool) -> Void
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// MARK: - SDImageLoader
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func canRequestImage(for url: URL?) -> Bool {
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return url?.scheme == "thumbhash"
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}
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func requestImage(
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with url: URL?,
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options: SDWebImageOptions = [],
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context: [SDWebImageContextOption: Any]?,
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progress progressBlock: SDImageLoaderProgressBlock?,
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completed completedBlock: ImageLoaderCompletedBlock? = nil
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) -> SDWebImageOperation? {
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guard let url else {
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let error = makeNSError(description: "URL provided to ThumbhashLoader is missing")
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completedBlock?(nil, nil, error, false)
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return nil
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}
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// The URI looks like this: thumbhash:/3OcRJYB4d3h\iIeHeEh3eIhw+j2w
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// ThumbHash may include slashes which could break the structure of the URL, so we replace them
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// with backslashes on the JS side and revert them back to slashes here, before generating the image.
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var thumbhash = url.pathComponents[1].replacingOccurrences(of: "\\", with: "/")
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// Thumbhashes with transparency cause the conversion to data to fail, padding the thumbhash string to correct length fixes that
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let remainder = thumbhash.count % 4
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if remainder > 0 {
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thumbhash = thumbhash.padding(toLength: thumbhash.count + 4 - remainder, withPad: "=", startingAt: 0)
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}
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guard !thumbhash.isEmpty, let thumbhashData = Data(base64Encoded: thumbhash, options: .ignoreUnknownCharacters) else {
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let error = makeNSError(description: "URL provided to ThumbhashLoader is invalid")
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completedBlock?(nil, nil, error, false)
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return nil
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}
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Task(priority: .high) {
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let image = image(fromThumbhash: thumbhashData)
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await MainActor.run {
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completedBlock?(image, nil, nil, true)
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}
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}
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return nil
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}
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func shouldBlockFailedURL(with url: URL, error: Error) -> Bool {
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return true
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}
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}
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