request cancellation

mobile/ios/Runner/Images/Thumbnails.g.swift

@@ -1,4 +1,4 @@
-// Autogenerated from Pigeon (v25.3.2), do not edit directly.
+// Autogenerated from Pigeon (v26.0.0), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 
 import Foundation
@@ -70,7 +70,8 @@ class ThumbnailsPigeonCodec: FlutterStandardMessageCodec, @unchecked Sendable {
 
 /// Generated protocol from Pigeon that represents a handler of messages from Flutter.
 protocol ThumbnailApi {
-  func getThumbnailBuffer(assetId: String, width: Int64, height: Int64, completion: @escaping (Result<[String: Int64], Error>) -> Void)
+  func requestImage(assetId: String, requestId: Int64, width: Int64, height: Int64, completion: @escaping (Result<[String: Int64], Error>) -> Void)
+  func cancelImageRequest(requestId: Int64) throws
 }
 
 /// Generated setup class from Pigeon to handle messages through the `binaryMessenger`.
@@ -79,14 +80,15 @@ class ThumbnailApiSetup {
   /// Sets up an instance of `ThumbnailApi` to handle messages through the `binaryMessenger`.
   static func setUp(binaryMessenger: FlutterBinaryMessenger, api: ThumbnailApi?, messageChannelSuffix: String = "") {
     let channelSuffix = messageChannelSuffix.count > 0 ? ".\(messageChannelSuffix)" : ""
-    let getThumbnailBufferChannel = FlutterBasicMessageChannel(name: "dev.flutter.pigeon.immich_mobile.ThumbnailApi.getThumbnailBuffer\(channelSuffix)", binaryMessenger: binaryMessenger, codec: codec)
+    let requestImageChannel = FlutterBasicMessageChannel(name: "dev.flutter.pigeon.immich_mobile.ThumbnailApi.requestImage\(channelSuffix)", binaryMessenger: binaryMessenger, codec: codec)
     if let api = api {
-      getThumbnailBufferChannel.setMessageHandler { message, reply in
+      requestImageChannel.setMessageHandler { message, reply in
         let args = message as! [Any?]
         let assetIdArg = args[0] as! String
-        let widthArg = args[1] as! Int64
-        let heightArg = args[2] as! Int64
-        api.getThumbnailBuffer(assetId: assetIdArg, width: widthArg, height: heightArg) { result in
+        let requestIdArg = args[1] as! Int64
+        let widthArg = args[2] as! Int64
+        let heightArg = args[3] as! Int64
+        api.requestImage(assetId: assetIdArg, requestId: requestIdArg, width: widthArg, height: heightArg) { result in
           switch result {
           case .success(let res):
             reply(wrapResult(res))
@@ -96,7 +98,22 @@ class ThumbnailApiSetup {
         }
       }
     } else {
-      getThumbnailBufferChannel.setMessageHandler(nil)
+      requestImageChannel.setMessageHandler(nil)
+    }
+    let cancelImageRequestChannel = FlutterBasicMessageChannel(name: "dev.flutter.pigeon.immich_mobile.ThumbnailApi.cancelImageRequest\(channelSuffix)", binaryMessenger: binaryMessenger, codec: codec)
+    if let api = api {
+      cancelImageRequestChannel.setMessageHandler { message, reply in
+        let args = message as! [Any?]
+        let requestIdArg = args[0] as! Int64
+        do {
+          try api.cancelImageRequest(requestId: requestIdArg)
+          reply(wrapResult(nil))
+        } catch {
+          reply(wrapError(error))
+        }
+      }
+    } else {
+      cancelImageRequestChannel.setMessageHandler(nil)
     }
   }
 }

mobile/ios/Runner/Images/ThumbnailsImpl.swift

@@ -3,6 +3,13 @@ import Flutter
 import MobileCoreServices
 import Photos
 
+struct Request {
+  var managerId: Int32?
+  var workItem: DispatchWorkItem?
+  var isCancelled = false
+  let callback: (Result<[String: Int64], any Error>) -> Void
+}
+
 class ThumbnailApiImpl: ThumbnailApi {
   private static let cacheManager = PHImageManager.default()
   private static let fetchOptions = {
@@ -22,29 +29,45 @@ class ThumbnailApiImpl: ThumbnailApi {
   private static let processingQueue = DispatchQueue(label: "thumbnail.processing", qos: .userInteractive, attributes: .concurrent)
   private static let rgbColorSpace = CGColorSpaceCreateDeviceRGB()
   private static let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.premultipliedLast.rawValue).rawValue
+  private static var requests = [Int64: Request]()
+  private static let cancelledResult = Result<[String: Int64], any Error>.success([:])
   
-  func getThumbnailBuffer(assetId: String, width: Int64, height: Int64, completion: @escaping (Result<[String: Int64], any Error>) -> Void) {
-    Self.processingQueue.async {
+  func requestImage(assetId: String, requestId: Int64, width: Int64, height: Int64, completion: @escaping (Result<[String: Int64], any Error>) -> Void) {
+    var request = Request(callback: completion)
+    let item = DispatchWorkItem {
       guard let asset = PHAsset.fetchAssets(withLocalIdentifiers: [assetId], options: Self.fetchOptions).firstObject
-      else { completion(.failure(PigeonError(code: "", message: "Could not get asset data for \(assetId)", details: nil))); return }
+      else {
+        Self.requests[requestId] = nil
+        completion(.failure(PigeonError(code: "", message: "Could not get asset data for \(assetId)", details: nil)))
+        return
+      }
       
-      Self.cacheManager.requestImage(
+      request.managerId = Self.cacheManager.requestImage(
         for: asset,
         targetSize: CGSize(width: Double(width), height: Double(height)),
         contentMode: .aspectFit,
         options: Self.requestOptions,
         resultHandler: { (image, info) -> Void in
+          defer { Self.requests[requestId] = nil }
           guard let image = image,
                 let cgImage = image.cgImage else {
-            completion(.failure(PigeonError(code: "", message: "Could not get pixel data for \(assetId)", details: nil)))
-            return
+            return completion(.failure(PigeonError(code: "", message: "Could not get pixel data for \(assetId)", details: nil)))
           }
-
+          
+          if request.isCancelled {
+            return completion(Self.cancelledResult)
+          }
+          
           let pointer = UnsafeMutableRawPointer.allocate(
             byteCount: Int(cgImage.width) * Int(cgImage.height) * 4,
             alignment: MemoryLayout<UInt8>.alignment
           )
           
+          if request.isCancelled {
+            pointer.deallocate()
+            return completion(Self.cancelledResult)
+          }
+          
           guard let context = CGContext(
             data: pointer,
             width: cgImage.width,
@@ -55,14 +78,41 @@ class ThumbnailApiImpl: ThumbnailApi {
             bitmapInfo: Self.bitmapInfo
           ) else {
             pointer.deallocate()
-            completion(.failure(PigeonError(code: "", message: "Could not create context for \(assetId)", details: nil)))
-            return
+            return completion(.failure(PigeonError(code: "", message: "Could not create context for \(assetId)", details: nil)))
           }
+          
+          if request.isCancelled {
+            pointer.deallocate()
+            return completion(Self.cancelledResult)
+          }
+          
           context.interpolationQuality = .none
           context.draw(cgImage, in: CGRect(x: 0, y: 0, width: cgImage.width, height: cgImage.height))
+          
+          if request.isCancelled {
+            pointer.deallocate()
+            return completion(Self.cancelledResult)
+          }
+          
           completion(.success(["pointer": Int64(Int(bitPattern: pointer)), "width": Int64(cgImage.width), "height": Int64(cgImage.height)]))
         }
       )
     }
+    
+    request.workItem = item
+    Self.requests[requestId] = request
+    Self.processingQueue.async(execute: item)
+  }
+  
+  func cancelImageRequest(requestId: Int64) {
+    guard var request = Self.requests.removeValue(forKey: requestId) else { return }
+    request.isCancelled = true
+    guard let item = request.workItem else { return }
+    item.cancel()
+    if item.isCancelled {
+      request.callback(Self.cancelledResult)
+    } else if let managerId = request.managerId {
+      Self.cacheManager.cancelImageRequest(managerId)
+    }
   }
 }