Source Code added

mobile/ios/Runner/Images/LocalImagesImpl.swift

@@ -0,0 +1,182 @@
+import Accelerate
+import Flutter
+import MobileCoreServices
+import Photos
+
+class LocalImageRequest {
+  weak var workItem: DispatchWorkItem?
+  var isCancelled = false
+  let callback: (Result<[String: Int64]?, any Error>) -> Void
+  
+  init(callback: @escaping (Result<[String: Int64]?, any Error>) -> Void) {
+    self.callback = callback
+  }
+}
+
+class LocalImageApiImpl: LocalImageApi {
+  private static let imageManager = PHImageManager.default()
+  private static let fetchOptions = {
+    let fetchOptions = PHFetchOptions()
+    fetchOptions.fetchLimit = 1
+    fetchOptions.wantsIncrementalChangeDetails = false
+    return fetchOptions
+  }()
+  private static let requestOptions = {
+    let requestOptions = PHImageRequestOptions()
+    requestOptions.isNetworkAccessAllowed = true
+    requestOptions.deliveryMode = .highQualityFormat
+    requestOptions.resizeMode = .fast
+    requestOptions.isSynchronous = true
+    requestOptions.version = .current
+    return requestOptions
+  }()
+  
+  private static let assetQueue = DispatchQueue(label: "thumbnail.assets", qos: .userInitiated)
+  private static let requestQueue = DispatchQueue(label: "thumbnail.requests", qos: .userInitiated)
+  private static let cancelQueue = DispatchQueue(label: "thumbnail.cancellation", qos: .default)
+  private static let processingQueue = DispatchQueue(label: "thumbnail.processing", qos: .userInteractive, attributes: .concurrent)
+  
+  private static var rgbaFormat = vImage_CGImageFormat(
+    bitsPerComponent: 8,
+    bitsPerPixel: 32,
+    colorSpace: CGColorSpaceCreateDeviceRGB(),
+    bitmapInfo: CGBitmapInfo(rawValue: CGImageAlphaInfo.premultipliedLast.rawValue),
+    renderingIntent: .defaultIntent
+  )!
+  private static var requests = [Int64: LocalImageRequest]()
+  private static let cancelledResult = Result<[String: Int64]?, any Error>.success(nil)
+  private static let concurrencySemaphore = DispatchSemaphore(value: ProcessInfo.processInfo.activeProcessorCount * 2)
+  private static let assetCache = {
+    let assetCache = NSCache<NSString, PHAsset>()
+    assetCache.countLimit = 10000
+    return assetCache
+  }()
+  
+  func getThumbhash(thumbhash: String, completion: @escaping (Result<[String : Int64], any Error>) -> Void) {
+    Self.processingQueue.async {
+      guard let data = Data(base64Encoded: thumbhash)
+      else { return completion(.failure(PigeonError(code: "", message: "Invalid base64 string: \(thumbhash)", details: nil)))}
+      
+      let (width, height, pointer) = thumbHashToRGBA(hash: data)
+      completion(.success([
+        "pointer": Int64(Int(bitPattern: pointer.baseAddress)),
+        "width": Int64(width),
+        "height": Int64(height),
+        "rowBytes": Int64(width * 4)
+      ]))
+    }
+  }
+  
+  func requestImage(assetId: String, requestId: Int64, width: Int64, height: Int64, isVideo: Bool, completion: @escaping (Result<[String: Int64]?, any Error>) -> Void) {
+    let request = LocalImageRequest(callback: completion)
+    let item = DispatchWorkItem {
+      if request.isCancelled {
+        return completion(Self.cancelledResult)
+      }
+      
+      Self.concurrencySemaphore.wait()
+      defer {
+        Self.concurrencySemaphore.signal()
+      }
+      
+      if request.isCancelled {
+        return completion(Self.cancelledResult)
+      }
+      
+      guard let asset = Self.requestAsset(assetId: assetId)
+      else {
+        Self.remove(requestId: requestId)
+        completion(.failure(PigeonError(code: "", message: "Could not get asset data for \(assetId)", details: nil)))
+        return
+      }
+      
+      if request.isCancelled {
+        return completion(Self.cancelledResult)
+      }
+      
+      var image: UIImage?
+      Self.imageManager.requestImage(
+        for: asset,
+        targetSize: width > 0 && height > 0 ? CGSize(width: Double(width), height: Double(height)) : PHImageManagerMaximumSize,
+        contentMode: .aspectFill,
+        options: Self.requestOptions,
+        resultHandler: { (_image, info) -> Void in
+          image = _image
+        }
+      )
+      
+      if request.isCancelled {
+        return completion(Self.cancelledResult)
+      }
+      
+      guard let image = image,
+            let cgImage = image.cgImage else {
+        Self.remove(requestId: requestId)
+        return completion(.failure(PigeonError(code: "", message: "Could not get pixel data for \(assetId)", details: nil)))
+      }
+      
+      if request.isCancelled {
+        return completion(Self.cancelledResult)
+      }
+      
+      do {
+        let buffer = try vImage_Buffer(cgImage: cgImage, format: Self.rgbaFormat)
+        
+        if request.isCancelled {
+          buffer.free()
+          return completion(Self.cancelledResult)
+        }
+        
+        request.callback(.success([
+          "pointer": Int64(Int(bitPattern: buffer.data)),
+          "width": Int64(buffer.width),
+          "height": Int64(buffer.height),
+          "rowBytes": Int64(buffer.rowBytes)
+        ]))
+        print("Successful response for \(requestId)")
+        Self.remove(requestId: requestId)
+      } catch {
+        Self.remove(requestId: requestId)
+        return completion(.failure(PigeonError(code: "", message: "Failed to convert image for \(assetId): \(error)", details: nil)))
+      }
+    }
+    
+    request.workItem = item
+    Self.add(requestId: requestId, request: request)
+    Self.processingQueue.async(execute: item)
+  }
+  
+  func cancelRequest(requestId: Int64) {
+    Self.cancel(requestId: requestId)
+  }
+  
+  private static func add(requestId: Int64, request: LocalImageRequest) -> Void {
+    requestQueue.sync { requests[requestId] = request }
+  }
+  
+  private static func remove(requestId: Int64) -> Void {
+    requestQueue.sync { requests[requestId] = nil }
+  }
+  
+  private static func cancel(requestId: Int64) -> Void {
+    requestQueue.async {
+      guard let request = requests.removeValue(forKey: requestId) else { return }
+      request.isCancelled = true
+      guard let item = request.workItem else { return }
+      if item.isCancelled {
+        cancelQueue.async { request.callback(Self.cancelledResult) }
+      }
+    }
+  }
+  
+  private static func requestAsset(assetId: String) -> PHAsset? {
+    var asset: PHAsset?
+    assetQueue.sync { asset = assetCache.object(forKey: assetId as NSString) }
+    if asset != nil { return asset }
+    
+    guard let asset = PHAsset.fetchAssets(withLocalIdentifiers: [assetId], options: Self.fetchOptions).firstObject
+    else { return nil }
+    assetQueue.async { assetCache.setObject(asset, forKey: assetId as NSString) }
+    return asset
+  }
+}