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node_modules/expo-image/ios/Utils/Blurhash.swift

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+// The blurhash algorithm was entirely created by Wolt Enterprises.
+// This implementation was inspired by:
+// - https://github.com/woltapp/blurhash/blob/master/Swift/BlurHashDecode.swift
+// - https://github.com/woltapp/blurhash/blob/master/Swift/BlurHashEncode.swift
+// See https://blurha.sh for more details about the blurhash.
+
+import UIKit
+
+// swiftlint:disable force_unwrapping
+
+internal func image(fromBlurhash blurhash: String, size: CGSize, punch: Float = 1.0) -> CGImage? {
+  guard blurhash.count >= 6 else {
+    return nil
+  }
+
+  let sizeFlag = decode83(String(blurhash[0]))
+  let numY = (sizeFlag / 9) + 1
+  let numX = (sizeFlag % 9) + 1
+
+  let quantisedMaximumValue = decode83(String(blurhash[1]))
+  let maximumValue = Float(quantisedMaximumValue + 1) / 166
+
+  guard blurhash.count == 4 + 2 * numX * numY else {
+    return nil
+  }
+
+  let colors: [(Float, Float, Float)] = (0 ..< numX * numY).map { i in
+    if i == 0 {
+      let value = decode83(String(blurhash[2 ..< 6]))
+      return decodeDC(value)
+    } else {
+      let value = decode83(String(blurhash[4 + i * 2 ..< 4 + i * 2 + 2]))
+      return decodeAC(value, maximumValue: maximumValue * punch)
+    }
+  }
+
+  let width = Int(size.width)
+  let height = Int(size.height)
+  let bytesPerRow = width * 3
+
+  guard let data = CFDataCreateMutable(kCFAllocatorDefault, bytesPerRow * height) else {
+    return nil
+  }
+
+  CFDataSetLength(data, bytesPerRow * height)
+
+  guard let pixels = CFDataGetMutableBytePtr(data) else {
+    return nil
+  }
+
+  for y in 0 ..< height {
+    for x in 0 ..< width {
+      var r: Float = 0
+      var g: Float = 0
+      var b: Float = 0
+
+      for j in 0 ..< numY {
+        for i in 0 ..< numX {
+          let basis = cos(Float.pi * Float(x) * Float(i) / Float(width)) * cos(Float.pi * Float(y) * Float(j) / Float(height))
+          let color = colors[i + j * numX]
+          r += color.0 * basis
+          g += color.1 * basis
+          b += color.2 * basis
+        }
+      }
+
+      let intR = UInt8(linearTosRGB(r))
+      let intG = UInt8(linearTosRGB(g))
+      let intB = UInt8(linearTosRGB(b))
+
+      pixels[3 * x + 0 + y * bytesPerRow] = intR
+      pixels[3 * x + 1 + y * bytesPerRow] = intG
+      pixels[3 * x + 2 + y * bytesPerRow] = intB
+    }
+  }
+
+  let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.none.rawValue)
+
+  guard let provider = CGDataProvider(data: data), let cgImage = CGImage(
+    width: width,
+    height: height,
+    bitsPerComponent: 8,
+    bitsPerPixel: 24,
+    bytesPerRow: bytesPerRow,
+    space: CGColorSpaceCreateDeviceRGB(),
+    bitmapInfo: bitmapInfo,
+    provider: provider,
+    decode: nil,
+    shouldInterpolate: true,
+    intent: .defaultIntent
+  ) else {
+    return nil
+  }
+
+  return cgImage
+}
+
+internal func blurhash(fromImage image: UIImage, numberOfComponents components: (Int, Int)) -> String? {
+  let size = image.size
+  let scale = image.scale
+
+  let pixelWidth = Int(round(size.width * scale))
+  let pixelHeight = Int(round(size.height * scale))
+
+  let context = CGContext(
+    data: nil,
+    width: pixelWidth,
+    height: pixelHeight,
+    bitsPerComponent: 8,
+    bytesPerRow: pixelWidth * 4,
+    space: CGColorSpace(name: CGColorSpace.sRGB)!,
+    bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue
+  )!
+  context.scaleBy(x: scale, y: -scale)
+  context.translateBy(x: 0, y: -size.height)
+
+  UIGraphicsPushContext(context)
+  image.draw(at: .zero)
+  UIGraphicsPopContext()
+
+  guard let cgImage = context.makeImage(),
+    let dataProvider = cgImage.dataProvider,
+    let data = dataProvider.data,
+    let pixels = CFDataGetBytePtr(data) else {
+    assertionFailure("Unexpected error!")
+    return nil
+  }
+
+  let width = cgImage.width
+  let height = cgImage.height
+  let bytesPerRow = cgImage.bytesPerRow
+
+  var factors: [(Float, Float, Float)] = []
+  for y in 0 ..< components.1 {
+    for x in 0 ..< components.0 {
+      let normalisation: Float = (x == 0 && y == 0) ? 1 : 2
+      let factor = multiplyBasisFunction(
+        pixels: pixels,
+        width: width,
+        height: height,
+        bytesPerRow: bytesPerRow,
+        bytesPerPixel: cgImage.bitsPerPixel / 8,
+        pixelOffset: 0
+      ) {
+        normalisation * cos(Float.pi * Float(x) * $0 / Float(width)) as Float * cos(Float.pi * Float(y) * $1 / Float(height)) as Float
+      }
+      factors.append(factor)
+    }
+  }
+
+  let dc = factors.first!
+  let ac = factors.dropFirst()
+
+  var hash = ""
+
+  let sizeFlag = (components.0 - 1) + (components.1 - 1) * 9
+  hash += encode83(sizeFlag, length: 1)
+
+  let maximumValue: Float
+  if !ac.isEmpty {
+    let actualMaximumValue = ac.map({ max(abs($0.0), abs($0.1), abs($0.2)) }).max()!
+    let quantisedMaximumValue = Int(max(0, min(82, floor(actualMaximumValue * 166 - 0.5))))
+    maximumValue = Float(quantisedMaximumValue + 1) / 166
+    hash += encode83(quantisedMaximumValue, length: 1)
+  } else {
+    maximumValue = 1
+    hash += encode83(0, length: 1)
+  }
+
+  hash += encode83(encodeDC(dc), length: 4)
+
+  for factor in ac {
+    hash += encode83(encodeAC(factor, maximumValue: maximumValue), length: 2)
+  }
+
+  return hash
+}
+
+internal func isBlurhash(_ str: String) -> Bool {
+  return str.allSatisfy { char in decodeCharacters[char] != nil }
+}
+
+// MARK: - Encode
+
+// swiftlint:disable:next function_parameter_count
+private func multiplyBasisFunction(
+  pixels: UnsafePointer<UInt8>,
+  width: Int,
+  height: Int,
+  bytesPerRow: Int,
+  bytesPerPixel: Int,
+  pixelOffset: Int,
+  basisFunction: (Float, Float) -> Float
+) -> (Float, Float, Float) {
+  var r: Float = 0
+  var g: Float = 0
+  var b: Float = 0
+
+  let buffer = UnsafeBufferPointer(start: pixels, count: height * bytesPerRow)
+
+  for x in 0 ..< width {
+    for y in 0 ..< height {
+      let basis = basisFunction(Float(x), Float(y))
+      r += basis * sRGBToLinear(buffer[bytesPerPixel * x + pixelOffset + 0 + y * bytesPerRow])
+      g += basis * sRGBToLinear(buffer[bytesPerPixel * x + pixelOffset + 1 + y * bytesPerRow])
+      b += basis * sRGBToLinear(buffer[bytesPerPixel * x + pixelOffset + 2 + y * bytesPerRow])
+    }
+  }
+
+  let scale = 1 / Float(width * height)
+
+  return (r * scale, g * scale, b * scale)
+}
+
+private let encodeCharacters: [Character] = Array("0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz#$%*+,-.:;=?@[]^_{|}~")
+
+private func encodeDC(_ value: (Float, Float, Float)) -> Int {
+  let roundedR = linearTosRGB(value.0)
+  let roundedG = linearTosRGB(value.1)
+  let roundedB = linearTosRGB(value.2)
+  return (roundedR << 16) + (roundedG << 8) + roundedB
+}
+
+private func encodeAC(_ value: (Float, Float, Float), maximumValue: Float) -> Int {
+  let quantR = Int(max(0, min(18, floor(signPow(value.0 / maximumValue, 0.5) * 9 + 9.5))))
+  let quantG = Int(max(0, min(18, floor(signPow(value.1 / maximumValue, 0.5) * 9 + 9.5))))
+  let quantB = Int(max(0, min(18, floor(signPow(value.2 / maximumValue, 0.5) * 9 + 9.5))))
+
+  return quantR * 19 * 19 + quantG * 19 + quantB
+}
+
+private func encode83(_ value: Int, length: Int) -> String {
+  var result = ""
+  for i in 1 ... length {
+    let digit = (value / pow(83, length - i)) % 83
+    result += String(encodeCharacters[Int(digit)])
+  }
+  return result
+}
+
+// MARK: - Decode
+
+private func decodeDC(_ value: Int) -> (Float, Float, Float) {
+  let intR = value >> 16
+  let intG = (value >> 8) & 255
+  let intB = value & 255
+  return (sRGBToLinear(intR), sRGBToLinear(intG), sRGBToLinear(intB))
+}
+
+private func decodeAC(_ value: Int, maximumValue: Float) -> (Float, Float, Float) {
+  let quantR = value / (19 * 19)
+  let quantG = (value / 19) % 19
+  let quantB = value % 19
+
+  let rgb = (
+    signPow((Float(quantR) - 9) / 9, 2) * maximumValue,
+    signPow((Float(quantG) - 9) / 9, 2) * maximumValue,
+    signPow((Float(quantB) - 9) / 9, 2) * maximumValue
+  )
+
+  return rgb
+}
+
+private let decodeCharacters: [Character: Int] = {
+  var dict: [Character: Int] = [:]
+  for (index, character) in encodeCharacters.enumerated() {
+    dict[character] = index
+  }
+  return dict
+}()
+
+private func decode83(_ str: String) -> Int {
+  var value: Int = 0
+  for character in str {
+    if let digit = decodeCharacters[character] {
+      value = value * 83 + digit
+    }
+  }
+  return value
+}
+
+// MARK: - Helpers
+
+private func signPow(_ value: Float, _ exp: Float) -> Float {
+  return copysign(pow(abs(value), exp), value)
+}
+
+private func linearTosRGB(_ value: Float) -> Int {
+  let v = max(0, min(1, value))
+  if v <= 0.0031308 {
+    return Int(v * 12.92 * 255 + 0.5)
+  } else {
+    return Int((1.055 * pow(v, 1 / 2.4) - 0.055) * 255 + 0.5)
+  }
+}
+
+private func sRGBToLinear<Type: BinaryInteger>(_ value: Type) -> Float {
+  let v = Float(Int64(value)) / 255
+  if v <= 0.04045 {
+    return v / 12.92
+  } else {
+    return pow((v + 0.055) / 1.055, 2.4)
+  }
+}
+
+private func pow(_ base: Int, _ exponent: Int) -> Int {
+  return (0 ..< exponent).reduce(1) { value, _ in value * base }
+}
+
+private extension String {
+  subscript (offset: Int) -> Character {
+    return self[index(startIndex, offsetBy: offset)]
+  }
+
+  subscript (bounds: CountableClosedRange<Int>) -> Substring {
+    let start = index(startIndex, offsetBy: bounds.lowerBound)
+    let end = index(startIndex, offsetBy: bounds.upperBound)
+    return self[start...end]
+  }
+
+  subscript (bounds: CountableRange<Int>) -> Substring {
+    let start = index(startIndex, offsetBy: bounds.lowerBound)
+    let end = index(startIndex, offsetBy: bounds.upperBound)
+    return self[start..<end]
+  }
+}

node_modules/expo-image/ios/Utils/ImageUtils.swift

@@ -0,0 +1,275 @@
+// Copyright 2022-present 650 Industries. All rights reserved.
+
+import SDWebImage
+import ExpoModulesCore
+
+/**
+ An exception to throw when it its not possible to generate a blurhash for a given URL.
+ */
+public final class BlurhashGenerationException: Exception {
+  override public var reason: String {
+    "Unable to generate blurhash, make sure the image exists at the given URL"
+  }
+}
+
+func cacheTypeToString(_ cacheType: SDImageCacheType) -> String {
+  switch cacheType {
+  case .none:
+    return "none"
+  case .disk:
+    return "disk"
+  case .memory, .all:
+    // `all` doesn't make much sense, so we treat it as `memory`.
+    return "memory"
+  @unknown default:
+    log.error("Unhandled `SDImageCacheType` value: \(cacheType), returning `none` as fallback. Add the missing case as soon as possible.")
+    return "none"
+  }
+}
+
+func imageFormatToMediaType(_ format: SDImageFormat) -> String? {
+  switch format {
+  case .undefined:
+    return nil
+  case .JPEG:
+    return "image/jpeg"
+  case .PNG:
+    return "image/png"
+  case .GIF:
+    return "image/gif"
+  case .TIFF:
+    return "image/tiff"
+  case .webP:
+    return "image/webp"
+  case .HEIC:
+    return "image/heic"
+  case .HEIF:
+    return "image/heif"
+  case .PDF:
+    return "application/pdf"
+  case .SVG:
+    return "image/svg+xml"
+  default:
+    // On one hand we could remove this clause and always ensure that we have handled
+    // all supported formats (by erroring compilation otherwise).
+    // On the other hand, we do support overriding SDWebImage version,
+    // so we shouldn't fail to compile on SDWebImage versions with.
+    return nil
+  }
+}
+
+/**
+ Calculates the ideal size that fills in the container size while maintaining the source aspect ratio.
+ */
+func idealSize(contentPixelSize: CGSize, containerSize: CGSize, scale: Double = 1.0, contentFit: ContentFit) -> CGSize {
+  switch contentFit {
+  case .contain:
+    let aspectRatio = min(containerSize.width / contentPixelSize.width, containerSize.height / contentPixelSize.height)
+    return contentPixelSize * aspectRatio
+  case .cover:
+    let aspectRatio = max(containerSize.width / contentPixelSize.width, containerSize.height / contentPixelSize.height)
+    return contentPixelSize * aspectRatio
+  case .fill:
+    return containerSize
+  case .scaleDown:
+    if containerSize.width < contentPixelSize.width / scale || containerSize.height < contentPixelSize.height / scale {
+      // The container is smaller than the image — scale it down and behave like `contain`
+      let aspectRatio = min(containerSize.width / contentPixelSize.width, containerSize.height / contentPixelSize.height)
+      return contentPixelSize * aspectRatio
+    } else {
+      // The container is bigger than the image — don't scale it and behave like `none`
+      return contentPixelSize / scale
+    }
+  case .none:
+    return contentPixelSize / scale
+  }
+}
+
+/**
+ Returns a bool whether the image should be downscaled to the given size.
+ */
+func shouldDownscale(image: UIImage, toSize size: CGSize, scale: Double) -> Bool {
+  if size.width <= 0 || size.height <= 0 {
+    // View is invisible, so no reason to keep the image in memory.
+    // This already ensures that we won't be diving by zero in ratio calculations.
+    return true
+  }
+  if size.width.isInfinite || size.height.isInfinite {
+    // Keep the image unscaled for infinite sizes.
+    return false
+  }
+  let imageSize = image.size * image.scale
+  return imageSize.width > (size.width * scale) && imageSize.height > (size.height * scale)
+}
+
+/**
+ Resizes a static image to fit in the given size and scale.
+ */
+func resize(image: UIImage, toSize size: CGSize, scale: Double) -> UIImage {
+  let format = UIGraphicsImageRendererFormat()
+  format.scale = scale
+
+  return UIGraphicsImageRenderer(size: size, format: format).image { _ in
+    image.draw(in: CGRect(origin: .zero, size: size))
+  }
+}
+
+/**
+ The image source that fits best into the given size, that is the one with the closest number of pixels.
+ May be `nil` if there are no sources available or the size is zero.
+ */
+func getBestSource(from sources: [ImageSource]?, forSize size: CGSize, scale: Double = 1.0) -> ImageSource? {
+  guard let sources = sources, !sources.isEmpty else {
+    return nil
+  }
+  if size.width <= 0 || size.height <= 0 {
+    return nil
+  }
+  if sources.count == 1 {
+    return sources.first
+  }
+  var bestSource: ImageSource?
+  var bestFit = Double.infinity
+  let targetPixelCount = size.width * size.height * scale * scale
+
+  for source in sources {
+    let fit = abs(1 - (source.pixelCount / targetPixelCount))
+
+    if fit < bestFit {
+      bestSource = source
+      bestFit = fit
+    }
+  }
+  return bestSource
+}
+
+/**
+ Creates the cache key filter that returns the specific string.
+ */
+func createCacheKeyFilter(_ cacheKey: String?) -> SDWebImageCacheKeyFilter? {
+  guard let cacheKey = cacheKey else {
+    return nil
+  }
+  return SDWebImageCacheKeyFilter { _ in
+    return cacheKey
+  }
+}
+
+/**
+ Creates a default image context based on the source and the cache policy.
+ */
+func createSDWebImageContext(forSource source: ImageSource, cachePolicy: ImageCachePolicy = .disk, useAppleWebpCodec: Bool = true) -> SDWebImageContext {
+  var context = SDWebImageContext()
+
+  // Modify URL request to add headers.
+  if let headers = source.headers {
+    context[.downloadRequestModifier] = SDWebImageDownloaderRequestModifier(headers: headers)
+  }
+
+  // Allow for custom cache key. If not specified in the source, its uri is used as the key.
+  context[.cacheKeyFilter] = createCacheKeyFilter(source.cacheKey)
+
+  // Tell SDWebImage to use our own class for animated formats,
+  // which has better compatibility with the UIImage and fixes issues with the image duration.
+  context[.animatedImageClass] = AnimatedImage.self
+
+  // Passing useAppleWebpCodec into WebPCoder
+  context[.imageDecodeOptions] = [
+    imageCoderOptionUseAppleWebpCodec: useAppleWebpCodec
+  ]
+
+  // Assets from the bundler have `scale` prop which needs to be passed to the context,
+  // otherwise they would be saved in cache with scale = 1.0 which may result in
+  // incorrectly rendered images for resize modes that don't scale (`center` and `repeat`).
+  context[.imageScaleFactor] = source.scale
+
+  let sdCacheType = cachePolicy.toSdCacheType().rawValue
+  context[.queryCacheType] = sdCacheType
+  context[.storeCacheType] = sdCacheType
+
+  if source.cacheOriginalImage {
+    context[.originalQueryCacheType] = sdCacheType
+    context[.originalStoreCacheType] = sdCacheType
+  } else {
+    context[.originalQueryCacheType] = SDImageCacheType.none.rawValue
+    context[.originalStoreCacheType] = SDImageCacheType.none.rawValue
+  }
+
+  // Some loaders (e.g. blurhash) may need access to the source.
+  context[ImageView.contextSourceKey] = source
+
+  return context
+}
+
+extension CGSize {
+  /**
+   Multiplies a size with a scalar.
+   */
+  static func * (size: CGSize, scalar: Double) -> CGSize {
+    return CGSize(width: size.width * scalar, height: size.height * scalar)
+  }
+
+  /**
+   Divides a size with a scalar.
+   */
+  static func / (size: CGSize, scalar: Double) -> CGSize {
+    return CGSize(width: size.width / scalar, height: size.height / scalar)
+  }
+
+  /**
+   Returns a new CGSize with width and height rounded to an integral value using the specified rounding rule.
+   */
+  func rounded(_ rule: FloatingPointRoundingRule) -> CGSize {
+    return CGSize(width: width.rounded(rule), height: height.rounded(rule))
+  }
+}
+
+func makeNSError(description: String) -> NSError {
+  let userInfo = [NSLocalizedDescriptionKey: description]
+  return NSError(domain: "expo.modules.image", code: 0, userInfo: userInfo)
+}
+
+// MARK: - Async helpers
+// TODO: Add helpers like these to the modules core eventually
+
+/**
+ Asynchronously maps the given sequence (sequentially).
+ */
+func asyncMap<ItemsType: Sequence, ResultType>(
+  _ items: ItemsType,
+  _ transform: (ItemsType.Element) async throws -> ResultType
+) async rethrows -> [ResultType] {
+  var values = [ResultType]()
+
+  for item in items {
+    try await values.append(transform(item))
+  }
+  return values
+}
+
+/**
+ Concurrently maps the given sequence.
+ */
+func concurrentMap<ItemsType: Sequence, ResultType: Sendable>(
+  _ items: ItemsType,
+  _ transform: @Sendable @escaping (ItemsType.Element) async throws -> ResultType
+) async rethrows -> [ResultType] where ItemsType.Element: Sendable {
+  return try await withThrowingTaskGroup(of: (Int, ResultType).self) { group in
+    var results = Array<ResultType?>.init(repeating: nil, count: Array(items).count)
+
+    // Enumerate items to preserve the original order in the output.
+    for (index, item) in Array(items).enumerated() {
+      group.addTask { [item] in
+        let value = try await transform(item)
+        return (index, value)
+      }
+    }
+
+    while let (index, value) = try await group.next() {
+      results[index] = value
+    }
+
+    // Compact map to unwrap optionals, all positions should be filled.
+    return results.compactMap { $0 }
+  }
+}

node_modules/expo-image/ios/Utils/Thumbhash.swift

@@ -0,0 +1,550 @@
+import Foundation
+
+// Blurhash implementation thanks to @evanw work
+// https://github.com/evanw/thumbhash
+
+// NOTE: Swift has an exponential-time type checker and compiling very simple
+// expressions can easily take many seconds, especially when expressions involve
+// numeric type constructors.
+//
+// This file deliberately breaks compound expressions up into separate variables
+// to improve compile time even though this comes at the expense of readability.
+// This is a known workaround for this deficiency in the Swift compiler.
+//
+// The following command is helpful when debugging Swift compile time issues:
+//
+//     swiftc ThumbHash.swift -Xfrontend -debug-time-function-bodies
+//
+// These optimizations brought the compile time for this file from around 2.5
+// seconds to around 250ms (10x faster).
+// NOTE: Swift's debug-build performance of for-in loops over numeric ranges is
+// really awful. Debug builds compile a very generic indexing iterator thing
+// that makes many nested calls for every iteration, which makes debug-build
+// performance crawl.
+//
+// This file deliberately avoids for-in loops that loop for more than a few
+// times to improve debug-build run time even though this comes at the expense
+// of readability. Similarly unsafe pointers are used instead of array getters
+// to avoid unnecessary bounds checks, which have extra overhead in debug builds.
+//
+// These optimizations brought the run time to encode and decode 10 ThumbHashes
+// in debug mode from 700ms to 70ms (10x faster).
+
+// swiftlint:disable all
+func rgbaToThumbHash(w: Int, h: Int, rgba: Data) -> Data {
+  // Encoding an image larger than 100x100 is slow with no benefit
+  assert(w <= 100 && h <= 100)
+  assert(rgba.count == w * h * 4)
+
+  // Determine the average color
+  var avg_r: Float32 = 0
+  var avg_g: Float32 = 0
+  var avg_b: Float32 = 0
+  var avg_a: Float32 = 0
+  rgba.withUnsafeBytes { rgba in
+    var rgba = rgba.baseAddress!.bindMemory(to: UInt8.self, capacity: rgba.count)
+    let n = w * h
+    var i = 0
+    while i < n {
+      let alpha = Float32(rgba[3]) / 255
+      avg_r += alpha / 255 * Float32(rgba[0])
+      avg_g += alpha / 255 * Float32(rgba[1])
+      avg_b += alpha / 255 * Float32(rgba[2])
+      avg_a += alpha
+      rgba = rgba.advanced(by: 4)
+      i += 1
+    }
+  }
+  if avg_a > 0 {
+    avg_r /= avg_a
+    avg_g /= avg_a
+    avg_b /= avg_a
+  }
+
+  let hasAlpha = avg_a < Float32(w * h)
+  let l_limit = hasAlpha ? 5 : 7 // Use fewer luminance bits if there's alpha
+  let imax_wh = max(w, h)
+  let iwl_limit = l_limit * w
+  let ihl_limit = l_limit * h
+  let fmax_wh = Float32(imax_wh)
+  let fwl_limit = Float32(iwl_limit)
+  let fhl_limit = Float32(ihl_limit)
+  let flx = round(fwl_limit / fmax_wh)
+  let fly = round(fhl_limit / fmax_wh)
+  var lx = Int(flx)
+  var ly = Int(fly)
+  lx = max(1, lx)
+  ly = max(1, ly)
+  var lpqa = [Float32](repeating: 0, count: w * h * 4)
+
+  // Convert the image from RGBA to LPQA (composite atop the average color)
+  rgba.withUnsafeBytes { rgba in
+    lpqa.withUnsafeMutableBytes { lpqa in
+      var rgba = rgba.baseAddress!.bindMemory(to: UInt8.self, capacity: rgba.count)
+      var lpqa = lpqa.baseAddress!.bindMemory(to: Float32.self, capacity: lpqa.count)
+      let n = w * h
+      var i = 0
+      while i < n {
+        let alpha = Float32(rgba[3]) / 255
+        let r = avg_r * (1 - alpha) + alpha / 255 * Float32(rgba[0])
+        let g = avg_g * (1 - alpha) + alpha / 255 * Float32(rgba[1])
+        let b = avg_b * (1 - alpha) + alpha / 255 * Float32(rgba[2])
+        lpqa[0] = (r + g + b) / 3
+        lpqa[1] = (r + g) / 2 - b
+        lpqa[2] = r - g
+        lpqa[3] = alpha
+        rgba = rgba.advanced(by: 4)
+        lpqa = lpqa.advanced(by: 4)
+        i += 1
+      }
+    }
+  }
+
+  // Encode using the DCT into DC (constant) and normalized AC (varying) terms
+  let encodeChannel = { (channel: UnsafePointer<Float32>, nx: Int, ny: Int) -> (Float32, [Float32], Float32) in
+    var dc: Float32 = 0
+    var ac: [Float32] = []
+    var scale: Float32 = 0
+    var fx = [Float32](repeating: 0, count: w)
+    fx.withUnsafeMutableBytes { fx in
+      let fx = fx.baseAddress!.bindMemory(to: Float32.self, capacity: fx.count)
+      var cy = 0
+      while cy < ny {
+        var cx = 0
+        while cx * ny < nx * (ny - cy) {
+          var ptr = channel
+          var f: Float32 = 0
+          var x = 0
+          while x < w {
+            let fw = Float32(w)
+            let fxx = Float32(x)
+            let fcx = Float32(cx)
+            fx[x] = cos(Float32.pi / fw * fcx * (fxx + 0.5))
+            x += 1
+          }
+          var y = 0
+          while y < h {
+            let fh = Float32(h)
+            let fyy = Float32(y)
+            let fcy = Float32(cy)
+            let fy = cos(Float32.pi / fh * fcy * (fyy + 0.5))
+            var x = 0
+            while x < w {
+              f += ptr.pointee * fx[x] * fy
+              x += 1
+              ptr = ptr.advanced(by: 4)
+            }
+            y += 1
+          }
+          f /= Float32(w * h)
+          if cx > 0 || cy > 0 {
+            ac.append(f)
+            scale = max(scale, abs(f))
+          } else {
+            dc = f
+          }
+          cx += 1
+        }
+        cy += 1
+      }
+    }
+    if scale > 0 {
+      let n = ac.count
+      var i = 0
+      while i < n {
+        ac[i] = 0.5 + 0.5 / scale * ac[i]
+        i += 1
+      }
+    }
+    return (dc, ac, scale)
+  }
+  let (
+    (l_dc, l_ac, l_scale),
+    (p_dc, p_ac, p_scale),
+    (q_dc, q_ac, q_scale),
+    (a_dc, a_ac, a_scale)
+  ) = lpqa.withUnsafeBytes { lpqa in
+    let lpqa = lpqa.baseAddress!.bindMemory(to: Float32.self, capacity: lpqa.count)
+    return (
+      encodeChannel(lpqa, max(3, lx), max(3, ly)),
+      encodeChannel(lpqa.advanced(by: 1), 3, 3),
+      encodeChannel(lpqa.advanced(by: 2), 3, 3),
+      hasAlpha ? encodeChannel(lpqa.advanced(by: 3), 5, 5) : (1, [], 1)
+    )
+  }
+
+  // Write the constants
+  let isLandscape = w > h
+  let fl_dc = round(63.0 * l_dc)
+  let fp_dc = round(31.5 + 31.5 * p_dc)
+  let fq_dc = round(31.5 + 31.5 * q_dc)
+  let fl_scale = round(31.0 * l_scale)
+  let il_dc = UInt32(fl_dc)
+  let ip_dc = UInt32(fp_dc)
+  let iq_dc = UInt32(fq_dc)
+  let il_scale = UInt32(fl_scale)
+  let ihasAlpha = UInt32(hasAlpha ? 1 : 0)
+  let header24 = il_dc | (ip_dc << 6) | (iq_dc << 12) | (il_scale << 18) | (ihasAlpha << 23)
+  let fp_scale = round(63.0 * p_scale)
+  let fq_scale = round(63.0 * q_scale)
+  let ilxy = UInt16(isLandscape ? ly : lx)
+  let ip_scale = UInt16(fp_scale)
+  let iq_scale = UInt16(fq_scale)
+  let iisLandscape = UInt16(isLandscape ? 1 : 0)
+  let header16 = ilxy | (ip_scale << 3) | (iq_scale << 9) | (iisLandscape << 15)
+  var hash = Data(capacity: 25)
+  hash.append(UInt8(header24 & 255))
+  hash.append(UInt8((header24 >> 8) & 255))
+  hash.append(UInt8(header24 >> 16))
+  hash.append(UInt8(header16 & 255))
+  hash.append(UInt8(header16 >> 8))
+  var isOdd = false
+  if hasAlpha {
+    let fa_dc = round(15.0 * a_dc)
+    let fa_scale = round(15.0 * a_scale)
+    let ia_dc = UInt8(fa_dc)
+    let ia_scale = UInt8(fa_scale)
+    hash.append(ia_dc | (ia_scale << 4))
+  }
+
+  // Write the varying factors
+  for ac in [l_ac, p_ac, q_ac] {
+    for f in ac {
+      let f15 = round(15.0 * f)
+      let i15 = UInt8(f15)
+      if isOdd {
+        hash[hash.count - 1] |= i15 << 4
+      } else {
+        hash.append(i15)
+      }
+      isOdd = !isOdd
+    }
+  }
+  if hasAlpha {
+    for f in a_ac {
+      let f15 = round(15.0 * f)
+      let i15 = UInt8(f15)
+      if isOdd {
+        hash[hash.count - 1] |= i15 << 4
+      } else {
+        hash.append(i15)
+      }
+      isOdd = !isOdd
+    }
+  }
+  return hash
+}
+
+func thumbHashToRGBA(hash: Data) -> (Int, Int, Data) {
+  // Read the constants
+  let h0 = UInt32(hash[0])
+  let h1 = UInt32(hash[1])
+  let h2 = UInt32(hash[2])
+  let h3 = UInt16(hash[3])
+  let h4 = UInt16(hash[4])
+  let header24 = h0 | (h1 << 8) | (h2 << 16)
+  let header16 = h3 | (h4 << 8)
+  let il_dc = header24 & 63
+  let ip_dc = (header24 >> 6) & 63
+  let iq_dc = (header24 >> 12) & 63
+  var l_dc = Float32(il_dc)
+  var p_dc = Float32(ip_dc)
+  var q_dc = Float32(iq_dc)
+  l_dc = l_dc / 63
+  p_dc = p_dc / 31.5 - 1
+  q_dc = q_dc / 31.5 - 1
+  let il_scale = (header24 >> 18) & 31
+  var l_scale = Float32(il_scale)
+  l_scale = l_scale / 31
+  let hasAlpha = (header24 >> 23) != 0
+  let ip_scale = (header16 >> 3) & 63
+  let iq_scale = (header16 >> 9) & 63
+  var p_scale = Float32(ip_scale)
+  var q_scale = Float32(iq_scale)
+  p_scale = p_scale / 63
+  q_scale = q_scale / 63
+  let isLandscape = (header16 >> 15) != 0
+  let lx16 = max(3, isLandscape ? hasAlpha ? 5 : 7 : header16 & 7)
+  let ly16 = max(3, isLandscape ? header16 & 7 : hasAlpha ? 5 : 7)
+  let lx = Int(lx16)
+  let ly = Int(ly16)
+  var a_dc = Float32(1)
+  var a_scale = Float32(1)
+  if hasAlpha {
+    let ia_dc = hash[5] & 15
+    let ia_scale = hash[5] >> 4
+    a_dc = Float32(ia_dc)
+    a_scale = Float32(ia_scale)
+    a_dc /= 15
+    a_scale /= 15
+  }
+
+  // Read the varying factors (boost saturation by 1.25x to compensate for quantization)
+  let ac_start = hasAlpha ? 6 : 5
+  var ac_index = 0
+  let decodeChannel = { (nx: Int, ny: Int, scale: Float32) -> [Float32] in
+    var ac: [Float32] = []
+    for cy in 0 ..< ny {
+      var cx = cy > 0 ? 0 : 1
+      while cx * ny < nx * (ny - cy) {
+        let iac = (hash[ac_start + (ac_index >> 1)] >> ((ac_index & 1) << 2)) & 15
+        var fac = Float32(iac)
+        fac = (fac / 7.5 - 1) * scale
+        ac.append(fac)
+        ac_index += 1
+        cx += 1
+      }
+    }
+    return ac
+  }
+  let l_ac = decodeChannel(lx, ly, l_scale)
+  let p_ac = decodeChannel(3, 3, p_scale * 1.25)
+  let q_ac = decodeChannel(3, 3, q_scale * 1.25)
+  let a_ac = hasAlpha ? decodeChannel(5, 5, a_scale) : []
+
+  // Decode using the DCT into RGB
+  let ratio = thumbHashToApproximateAspectRatio(hash: hash)
+  let fw = round(ratio > 1 ? 32 : 32 * ratio)
+  let fh = round(ratio > 1 ? 32 / ratio : 32)
+  let w = Int(fw)
+  let h = Int(fh)
+  var rgba = Data(count: w * h * 4)
+  let cx_stop = max(lx, hasAlpha ? 5 : 3)
+  let cy_stop = max(ly, hasAlpha ? 5 : 3)
+  var fx = [Float32](repeating: 0, count: cx_stop)
+  var fy = [Float32](repeating: 0, count: cy_stop)
+  fx.withUnsafeMutableBytes { fx in
+    let fx = fx.baseAddress!.bindMemory(to: Float32.self, capacity: fx.count)
+    fy.withUnsafeMutableBytes { fy in
+      let fy = fy.baseAddress!.bindMemory(to: Float32.self, capacity: fy.count)
+      rgba.withUnsafeMutableBytes { rgba in
+        var rgba = rgba.baseAddress!.bindMemory(to: UInt8.self, capacity: rgba.count)
+        var y = 0
+        while y < h {
+          var x = 0
+          while x < w {
+            var l = l_dc
+            var p = p_dc
+            var q = q_dc
+            var a = a_dc
+
+            // Precompute the coefficients
+            var cx = 0
+            while cx < cx_stop {
+              let fw = Float32(w)
+              let fxx = Float32(x)
+              let fcx = Float32(cx)
+              fx[cx] = cos(Float32.pi / fw * (fxx + 0.5) * fcx)
+              cx += 1
+            }
+            var cy = 0
+            while cy < cy_stop {
+              let fh = Float32(h)
+              let fyy = Float32(y)
+              let fcy = Float32(cy)
+              fy[cy] = cos(Float32.pi / fh * (fyy + 0.5) * fcy)
+              cy += 1
+            }
+
+            // Decode L
+            var j = 0
+            cy = 0
+            while cy < ly {
+              var cx = cy > 0 ? 0 : 1
+              let fy2 = fy[cy] * 2
+              while cx * ly < lx * (ly - cy) {
+                l += l_ac[j] * fx[cx] * fy2
+                j += 1
+                cx += 1
+              }
+              cy += 1
+            }
+
+            // Decode P and Q
+            j = 0
+            cy = 0
+            while cy < 3 {
+              var cx = cy > 0 ? 0 : 1
+              let fy2 = fy[cy] * 2
+              while cx < 3 - cy {
+                let f = fx[cx] * fy2
+                p += p_ac[j] * f
+                q += q_ac[j] * f
+                j += 1
+                cx += 1
+              }
+              cy += 1
+            }
+
+            // Decode A
+            if hasAlpha {
+              j = 0
+              cy = 0
+              while cy < 5 {
+                var cx = cy > 0 ? 0 : 1
+                let fy2 = fy[cy] * 2
+                while cx < 5 - cy {
+                  a += a_ac[j] * fx[cx] * fy2
+                  j += 1
+                  cx += 1
+                }
+                cy += 1
+              }
+            }
+
+            // Convert to RGB
+            var b = l - 2 / 3 * p
+            var r = (3 * l - b + q) / 2
+            var g = r - q
+            r = max(0, 255 * min(1, r))
+            g = max(0, 255 * min(1, g))
+            b = max(0, 255 * min(1, b))
+            a = max(0, 255 * min(1, a))
+            rgba[0] = UInt8(r)
+            rgba[1] = UInt8(g)
+            rgba[2] = UInt8(b)
+            rgba[3] = UInt8(a)
+            rgba = rgba.advanced(by: 4)
+            x += 1
+          }
+          y += 1
+        }
+      }
+    }
+  }
+  return (w, h, rgba)
+}
+
+func thumbHashToAverageRGBA(hash: Data) -> (Float32, Float32, Float32, Float32) {
+  let h0 = UInt32(hash[0])
+  let h1 = UInt32(hash[1])
+  let h2 = UInt32(hash[2])
+  let header = h0 | (h1 << 8) | (h2 << 16)
+  let il = header & 63
+  let ip = (header >> 6) & 63
+  let iq = (header >> 12) & 63
+  var l = Float32(il)
+  var p = Float32(ip)
+  var q = Float32(iq)
+  l = l / 63
+  p = p / 31.5 - 1
+  q = q / 31.5 - 1
+  let hasAlpha = (header >> 23) != 0
+  var a = Float32(1)
+  if hasAlpha {
+    let ia = hash[5] & 15
+    a = Float32(ia)
+    a = a / 15
+  }
+  let b = l - 2 / 3 * p
+  let r = (3 * l - b + q) / 2
+  let g = r - q
+  return (
+    max(0, min(1, r)),
+    max(0, min(1, g)),
+    max(0, min(1, b)),
+    a
+  )
+}
+
+func thumbHashToApproximateAspectRatio(hash: Data) -> Float32 {
+  let header = hash[3]
+  let hasAlpha = (hash[2] & 0x80) != 0
+  let isLandscape = (hash[4] & 0x80) != 0
+  let lx = isLandscape ? hasAlpha ? 5 : 7 : header & 7
+  let ly = isLandscape ? header & 7 : hasAlpha ? 5 : 7
+  return Float32(lx) / Float32(ly)
+}
+
+#if os(iOS) || os(tvOS)
+import UIKit
+
+func thumbHash(fromImage: UIImage) -> Data {
+  let size = fromImage.size
+  let w = Int(round(100 * size.width / max(size.width, size.height)))
+  let h = Int(round(100 * size.height / max(size.width, size.height)))
+  var rgba = Data(count: w * h * 4)
+  rgba.withUnsafeMutableBytes { rgba in
+    if
+      let space = fromImage.cgImage?.colorSpace,
+      let context = CGContext(
+        data: rgba.baseAddress,
+        width: w,
+        height: h,
+        bitsPerComponent: 8,
+        bytesPerRow: w * 4,
+        space: space,
+        bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue
+      )
+    {
+      // EXIF orientation only works if you draw the UIImage, not the CGImage
+      context.concatenate(CGAffineTransform(1, 0, 0, -1, 0, CGFloat(h)))
+      UIGraphicsPushContext(context)
+      fromImage.draw(in: CGRect(x: 0, y: 0, width: w, height: h))
+      UIGraphicsPopContext()
+
+      // Convert from premultiplied alpha to unpremultiplied alpha
+      var rgba = rgba.baseAddress!.bindMemory(to: UInt8.self, capacity: rgba.count)
+      let n = w * h
+      var i = 0
+      while i < n {
+        let a = UInt16(rgba[3])
+        if a > 0 && a < 255 {
+          var r = UInt16(rgba[0])
+          var g = UInt16(rgba[1])
+          var b = UInt16(rgba[2])
+          r = min(255, r * 255 / a)
+          g = min(255, g * 255 / a)
+          b = min(255, b * 255 / a)
+          rgba[0] = UInt8(r)
+          rgba[1] = UInt8(g)
+          rgba[2] = UInt8(b)
+        }
+        rgba = rgba.advanced(by: 4)
+        i += 1
+      }
+    }
+  }
+  return rgbaToThumbHash(w: w, h: h, rgba: rgba)
+}
+
+func image(fromThumbhash: Data) -> UIImage {
+  var (w, h, rgba) = thumbHashToRGBA(hash: fromThumbhash)
+  rgba.withUnsafeMutableBytes { rgba in
+    // Convert from unpremultiplied alpha to premultiplied alpha
+    var rgba = rgba.baseAddress!.bindMemory(to: UInt8.self, capacity: rgba.count)
+    let n = w * h
+    var i = 0
+    while i < n {
+      let a = UInt16(rgba[3])
+      if a < 255 {
+        var r = UInt16(rgba[0])
+        var g = UInt16(rgba[1])
+        var b = UInt16(rgba[2])
+        r = min(255, r * a / 255)
+        g = min(255, g * a / 255)
+        b = min(255, b * a / 255)
+        rgba[0] = UInt8(r)
+        rgba[1] = UInt8(g)
+        rgba[2] = UInt8(b)
+      }
+      rgba = rgba.advanced(by: 4)
+      i += 1
+    }
+  }
+  let image = CGImage(
+    width: w,
+    height: h,
+    bitsPerComponent: 8,
+    bitsPerPixel: 32,
+    bytesPerRow: w * 4,
+    space: CGColorSpaceCreateDeviceRGB(),
+    bitmapInfo: CGBitmapInfo(rawValue: CGBitmapInfo.byteOrder32Big.rawValue | CGImageAlphaInfo.premultipliedLast.rawValue),
+    provider: CGDataProvider(data: rgba as CFData)!,
+    decode: nil,
+    shouldInterpolate: true,
+    intent: .perceptual
+  )
+  return UIImage(cgImage: image!)
+}
+#endif