kotlin impl, avoid message passing overhead

mobile/android/app/CMakeLists.txt

@@ -0,0 +1,10 @@
+
+cmake_minimum_required(VERSION 3.10.2)
+project("native_buffer")
+
+add_library(native_buffer SHARED
+    src/main/cpp/native_buffer.c)
+
+find_library(log-lib log)
+
+target_link_libraries(native_buffer ${log-lib})

mobile/android/app/build.gradle

@@ -83,6 +83,12 @@ android {
     }
   }
   namespace 'app.alextran.immich'
+
+  externalNativeBuild {
+    cmake {
+      path "CMakeLists.txt"
+    }
+  }
 }
 
 flutter {

mobile/android/app/src/main/cpp/native_buffer.c

@@ -0,0 +1,13 @@
+#include <jni.h>
+
+JNIEXPORT jobject JNICALL
+Java_app_alextran_immich_images_ThumbnailsImpl_00024Companion_wrapPointer(
+    JNIEnv *env, jclass clazz, jlong address, jint capacity) {
+    return (*env)->NewDirectByteBuffer(env, (void*)address, capacity);
+}
+
+JNIEXPORT jobject JNICALL
+Java_app_alextran_immich_images_ThumbnailsImpl_wrapPointer(
+    JNIEnv *env, jclass clazz, jlong address, jint capacity) {
+    return (*env)->NewDirectByteBuffer(env, (void*)address, capacity);
+}

mobile/android/app/src/main/kotlin/app/alextran/immich/MainActivity.kt

@@ -2,7 +2,8 @@ package app.alextran.immich
 
 import android.os.Build
 import android.os.ext.SdkExtensions
-import androidx.annotation.NonNull
+import app.alextran.immich.images.ThumbnailApi
+import app.alextran.immich.images.ThumbnailsImpl
 import app.alextran.immich.sync.NativeSyncApi
 import app.alextran.immich.sync.NativeSyncApiImpl26
 import app.alextran.immich.sync.NativeSyncApiImpl30
@@ -10,7 +11,7 @@ import io.flutter.embedding.android.FlutterFragmentActivity
 import io.flutter.embedding.engine.FlutterEngine
 
 class MainActivity : FlutterFragmentActivity() {
-  override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {
+  override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
     super.configureFlutterEngine(flutterEngine)
     flutterEngine.plugins.add(BackgroundServicePlugin())
     flutterEngine.plugins.add(HttpSSLOptionsPlugin())
@@ -23,5 +24,6 @@ class MainActivity : FlutterFragmentActivity() {
         NativeSyncApiImpl30(this)
       }
     NativeSyncApi.setUp(flutterEngine.dartExecutor.binaryMessenger, nativeSyncApiImpl)
+    ThumbnailApi.setUp(flutterEngine.dartExecutor.binaryMessenger, ThumbnailsImpl(this))
   }
 }

mobile/android/app/src/main/kotlin/app/alextran/immich/images/Thumbnails.g.kt

@@ -59,7 +59,7 @@ private open class ThumbnailsPigeonCodec : StandardMessageCodec() {
 
 /** Generated interface from Pigeon that represents a handler of messages from Flutter. */
 interface ThumbnailApi {
-  fun getThumbnail(assetId: String, width: Long, height: Long, callback: (Result<ByteArray>) -> Unit)
+  fun setThumbnailToBuffer(pointer: Long, assetId: String, width: Long, height: Long, callback: (Result<Unit>) -> Unit)
 
   companion object {
     /** The codec used by ThumbnailApi. */
@@ -71,20 +71,20 @@ interface ThumbnailApi {
     fun setUp(binaryMessenger: BinaryMessenger, api: ThumbnailApi?, messageChannelSuffix: String = "") {
       val separatedMessageChannelSuffix = if (messageChannelSuffix.isNotEmpty()) ".$messageChannelSuffix" else ""
       run {
-        val channel = BasicMessageChannel<Any?>(binaryMessenger, "dev.flutter.pigeon.immich_mobile.ThumbnailApi.getThumbnail$separatedMessageChannelSuffix", codec)
+        val channel = BasicMessageChannel<Any?>(binaryMessenger, "dev.flutter.pigeon.immich_mobile.ThumbnailApi.setThumbnailToBuffer$separatedMessageChannelSuffix", codec)
         if (api != null) {
           channel.setMessageHandler { message, reply ->
             val args = message as List<Any?>
-            val assetIdArg = args[0] as String
-            val widthArg = args[1] as Long
-            val heightArg = args[2] as Long
-            api.getThumbnail(assetIdArg, widthArg, heightArg) { result: Result<ByteArray> ->
+            val pointerArg = args[0] as Long
+            val assetIdArg = args[1] as String
+            val widthArg = args[2] as Long
+            val heightArg = args[3] as Long
+            api.setThumbnailToBuffer(pointerArg, assetIdArg, widthArg, heightArg) { result: Result<Unit> ->
               val error = result.exceptionOrNull()
               if (error != null) {
                 reply.reply(ThumbnailsPigeonUtils.wrapError(error))
               } else {
-                val data = result.getOrNull()
-                reply.reply(ThumbnailsPigeonUtils.wrapResult(data))
+                reply.reply(ThumbnailsPigeonUtils.wrapResult(null))
               }
             }
           }

mobile/android/app/src/main/kotlin/app/alextran/immich/images/ThumbnailsImpl.kt

@@ -0,0 +1,148 @@
+package app.alextran.immich.images
+
+import android.content.ContentResolver
+import android.content.ContentUris
+import android.content.Context
+import android.graphics.*
+import android.media.MediaMetadataRetriever
+import android.media.ThumbnailUtils
+import android.net.Uri
+import android.os.Build
+import android.provider.MediaStore
+import android.util.Size
+import java.nio.ByteBuffer
+import kotlin.math.max
+import java.util.concurrent.Executors
+
+class ThumbnailsImpl(context: Context) : ThumbnailApi {
+  private val ctx: Context = context.applicationContext
+  private val contentResolver: ContentResolver = ctx.contentResolver
+  private val threadPool =
+    Executors.newFixedThreadPool(max(4, Runtime.getRuntime().availableProcessors()))
+
+  companion object {
+    val PROJECTION = arrayOf(
+      MediaStore.MediaColumns.DATE_MODIFIED,
+      MediaStore.Files.FileColumns.MEDIA_TYPE,
+    )
+    const val SELECTION = "${MediaStore.MediaColumns._ID} = ?"
+    val URI: Uri = MediaStore.Files.getContentUri("external")
+
+    const val MEDIA_TYPE_IMAGE = MediaStore.Files.FileColumns.MEDIA_TYPE_IMAGE
+    const val MEDIA_TYPE_VIDEO = MediaStore.Files.FileColumns.MEDIA_TYPE_VIDEO
+
+    init {
+      System.loadLibrary("native_buffer")
+    }
+
+    @JvmStatic
+    external fun wrapPointer(address: Long, capacity: Int): ByteBuffer
+  }
+
+  override fun setThumbnailToBuffer(
+    pointer: Long,
+    assetId: String,
+    width: Long,
+    height: Long,
+    callback: (Result<Unit>) -> Unit
+  ) {
+    threadPool.execute {
+      try {
+        val targetWidth = width.toInt()
+        val targetHeight = height.toInt()
+
+        val cursor = contentResolver.query(URI, PROJECTION, SELECTION, arrayOf(assetId), null)
+          ?: return@execute callback(Result.failure(RuntimeException("Asset not found")))
+
+        cursor.use { c ->
+          if (!c.moveToNext()) {
+            return@execute callback(Result.failure(RuntimeException("Asset not found")))
+          }
+
+          val mediaType = c.getInt(1)
+          val bitmap = when (mediaType) {
+            MEDIA_TYPE_IMAGE -> decodeImageThumbnail(assetId, targetWidth, targetHeight)
+            MEDIA_TYPE_VIDEO -> decodeVideoThumbnail(assetId, targetWidth, targetHeight)
+            else -> return@execute callback(Result.failure(RuntimeException("Unsupported media type")))
+          }
+
+          val croppedBitmap = ThumbnailUtils.extractThumbnail(
+            bitmap,
+            targetWidth,
+            targetHeight,
+            ThumbnailUtils.OPTIONS_RECYCLE_INPUT
+          )
+          val buffer = wrapPointer(pointer, (width * height * 4).toInt())
+          croppedBitmap.copyPixelsToBuffer(buffer)
+          croppedBitmap.recycle()
+          callback(Result.success(Unit))
+        }
+      } catch (e: Exception) {
+        callback(Result.failure(e))
+      }
+    }
+  }
+
+  private fun decodeImageThumbnail(assetId: String, targetWidth: Int, targetHeight: Int): Bitmap {
+    val uri =
+      ContentUris.withAppendedId(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, assetId.toLong())
+    return if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
+      contentResolver.loadThumbnail(uri, Size(targetWidth, targetHeight), null)
+    } else {
+      decodeSampledBitmap(uri, targetWidth, targetHeight)
+    }
+  }
+
+  private fun decodeVideoThumbnail(assetId: String, targetWidth: Int, targetHeight: Int): Bitmap {
+    val uri =
+      ContentUris.withAppendedId(MediaStore.Video.Media.EXTERNAL_CONTENT_URI, assetId.toLong())
+    return if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
+      contentResolver.loadThumbnail(uri, Size(targetWidth, targetHeight), null)
+    } else {
+      val retriever = MediaMetadataRetriever()
+      try {
+        retriever.setDataSource(ctx, uri)
+        retriever.getFrameAtTime(0L) ?: throw RuntimeException("Failed to extract video frame")
+      } finally {
+        retriever.release()
+      }
+    }
+  }
+
+  private fun decodeSampledBitmap(uri: Uri, targetWidth: Int, targetHeight: Int): Bitmap {
+    val options = BitmapFactory.Options().apply {
+      inJustDecodeBounds = true
+    }
+
+    contentResolver.openInputStream(uri)?.use { stream ->
+      BitmapFactory.decodeStream(stream, null, options)
+    }
+
+    options.apply {
+      inSampleSize = getSampleSize(this, targetWidth, targetHeight)
+      inJustDecodeBounds = false
+      inPreferredConfig = Bitmap.Config.ARGB_8888
+    }
+
+    return contentResolver.openInputStream(uri)?.use { stream ->
+      BitmapFactory.decodeStream(stream, null, options)
+    } ?: throw RuntimeException("Failed to decode bitmap")
+  }
+
+  private fun getSampleSize(options: BitmapFactory.Options, reqWidth: Int, reqHeight: Int): Int {
+    val height = options.outHeight
+    val width = options.outWidth
+    var inSampleSize = 1
+
+    if (height > reqHeight || width > reqWidth) {
+      val halfHeight = height / 2
+      val halfWidth = width / 2
+
+      while ((halfHeight / inSampleSize) >= reqHeight && (halfWidth / inSampleSize) >= reqWidth) {
+        inSampleSize *= 2
+      }
+    }
+
+    return inSampleSize
+  }
+}

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

@@ -70,7 +70,7 @@ class ThumbnailsPigeonCodec: FlutterStandardMessageCodec, @unchecked Sendable {
 
 /// Generated protocol from Pigeon that represents a handler of messages from Flutter.
 protocol ThumbnailApi {
-  func getThumbnail(assetId: String, width: Int64, height: Int64, completion: @escaping (Result<FlutterStandardTypedData, Error>) -> Void)
+  func setThumbnailToBuffer(pointer: Int64, assetId: String, width: Int64, height: Int64, completion: @escaping (Result<Void, Error>) -> Void)
 }
 
 /// Generated setup class from Pigeon to handle messages through the `binaryMessenger`.
@@ -79,24 +79,25 @@ 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 getThumbnailChannel = FlutterBasicMessageChannel(name: "dev.flutter.pigeon.immich_mobile.ThumbnailApi.getThumbnail\(channelSuffix)", binaryMessenger: binaryMessenger, codec: codec)
+    let setThumbnailToBufferChannel = FlutterBasicMessageChannel(name: "dev.flutter.pigeon.immich_mobile.ThumbnailApi.setThumbnailToBuffer\(channelSuffix)", binaryMessenger: binaryMessenger, codec: codec)
     if let api = api {
-      getThumbnailChannel.setMessageHandler { message, reply in
+      setThumbnailToBufferChannel.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.getThumbnail(assetId: assetIdArg, width: widthArg, height: heightArg) { result in
+        let pointerArg = args[0] as! Int64
+        let assetIdArg = args[1] as! String
+        let widthArg = args[2] as! Int64
+        let heightArg = args[3] as! Int64
+        api.setThumbnailToBuffer(pointer: pointerArg, assetId: assetIdArg, width: widthArg, height: heightArg) { result in
           switch result {
-          case .success(let res):
-            reply(wrapResult(res))
+          case .success:
+            reply(wrapResult(nil))
           case .failure(let error):
             reply(wrapError(error))
           }
         }
       }
     } else {
-      getThumbnailChannel.setMessageHandler(nil)
+      setThumbnailToBufferChannel.setMessageHandler(nil)
     }
   }
 }

mobile/ios/Runner/Images/ThumbnailsImpl.swift

@@ -3,64 +3,6 @@ import Flutter
 import MobileCoreServices
 import Photos
 
-// https://stackoverflow.com/a/55839062
-extension UIImage {
-  func toData(options: NSDictionary?, type: ImageType) -> Data? {
-    guard cgImage != nil else { return nil }
-    return toData(options: options, type: type.value)
-  }
-
-  // about properties: https://developer.apple.com/documentation/imageio/1464962-cgimagedestinationaddimage
-  func toData(options: NSDictionary?, type: CFString) -> Data? {
-    guard let cgImage = cgImage else { return nil }
-    return autoreleasepool { () -> Data? in
-      let data = NSMutableData()
-      guard
-        let imageDestination = CGImageDestinationCreateWithData(data as CFMutableData, type, 1, nil)
-      else { return nil }
-      CGImageDestinationAddImage(imageDestination, cgImage, options)
-      CGImageDestinationFinalize(imageDestination)
-      return data as Data
-    }
-  }
-
-  enum ImageType {
-    case image  // abstract image data
-    case jpeg  // JPEG image
-    case jpeg2000  // JPEG-2000 image
-    case tiff  // TIFF image
-    case pict  // Quickdraw PICT format
-    case gif  // GIF image
-    case png  // PNG image
-    case quickTimeImage  // QuickTime image format (OSType 'qtif')
-    case appleICNS  // Apple icon data
-    case bmp  // Windows bitmap
-    case ico  // Windows icon data
-    case rawImage  // base type for raw image data (.raw)
-    case scalableVectorGraphics  // SVG image
-    case livePhoto  // Live Photo
-
-    var value: CFString {
-      switch self {
-      case .image: return kUTTypeImage
-      case .jpeg: return kUTTypeJPEG
-      case .jpeg2000: return kUTTypeJPEG2000
-      case .tiff: return kUTTypeTIFF
-      case .pict: return kUTTypePICT
-      case .gif: return kUTTypeGIF
-      case .png: return kUTTypePNG
-      case .quickTimeImage: return kUTTypeQuickTimeImage
-      case .appleICNS: return kUTTypeAppleICNS
-      case .bmp: return kUTTypeBMP
-      case .ico: return kUTTypeICO
-      case .rawImage: return kUTTypeRawImage
-      case .scalableVectorGraphics: return kUTTypeScalableVectorGraphics
-      case .livePhoto: return kUTTypeLivePhoto
-      }
-    }
-  }
-}
-
 class ThumbnailApiImpl: ThumbnailApi {
   private static let cacheManager = PHImageManager.default()
   private static let fetchOptions = {
@@ -77,36 +19,44 @@ class ThumbnailApiImpl: ThumbnailApi {
     requestOptions.version = .current
     return requestOptions
   }()
-  private static let processingQueue = DispatchQueue(
-    label: "thumbnail.processing", qos: .userInteractive, attributes: .concurrent)
-
-  func getThumbnail(
-    assetId: String,
-    width: Int64,
-    height: Int64,
-    completion: @escaping (Result<FlutterStandardTypedData, Error>) -> Void
-  ) {
+  private static let processingQueue = DispatchQueue(label: "thumbnail.processing", qos: .userInteractive, attributes: .concurrent)
+  
+  func setThumbnailToBuffer(pointer: Int64, assetId: String, width: Int64, height: Int64, completion: @escaping (Result<Void, any Error>) -> Void) {
+    guard let bufferPointer = UnsafeMutableRawPointer(bitPattern: Int(pointer))
+    else { completion(.failure(PigeonError(code: "", message: "Could not get buffer pointer for \(assetId)", details: nil))); return }
     Self.processingQueue.async {
       do {
         let asset = try self.getAsset(assetId: assetId)
-
         Self.cacheManager.requestImage(
           for: asset,
           targetSize: CGSize(width: Double(width), height: Double(height)),
           contentMode: .aspectFill,
           options: Self.requestOptions,
           resultHandler: { (image, info) -> Void in
-            guard let data = image?.toData(options: nil, type: .bmp) else { return }
-            completion(.success(FlutterStandardTypedData(bytes: data)))
+            guard let image = image,
+                  let cgImage = image.cgImage,
+                  let dataProvider = cgImage.dataProvider,
+                  let pixelData = dataProvider.data
+            else { completion(.failure(PigeonError(code: "", message: "Could not get pixel data for \(assetId)", details: nil))); return }
+            
+            guard let sourceBuffer = CFDataGetBytePtr(pixelData)
+            else { completion(.failure(PigeonError(code: "", message: "Could not get pixel data buffer for \(assetId)", details: nil))); return }
+            let dataLength = CFDataGetLength(pixelData)
+            let bufferLength = width * height * 4
+            guard dataLength <= bufferLength
+            else { completion(.failure(PigeonError(code: "", message: "Buffer is not large enough (\(bufferLength) vs \(dataLength) for \(assetId)", details: nil))); return }
+            
+            bufferPointer.copyMemory(from: sourceBuffer, byteCount: dataLength)
+            completion(.success(()))
           }
         )
       } catch {
         completion(
-          .failure(PigeonError(code: "", message: "Could not get asset data", details: nil)))
+          .failure(PigeonError(code: "", message: "Could not get asset data for \(assetId)", details: nil)))
       }
     }
   }
-
+  
   private func getAsset(assetId: String) throws -> PHAsset {
     guard
       let asset = PHAsset.fetchAssets(withLocalIdentifiers: [assetId], options: Self.fetchOptions)
@@ -116,9 +66,4 @@ class ThumbnailApiImpl: ThumbnailApi {
     }
     return asset
   }
-
-  // func cancel(requestId: Int32) {
-  //   Self.cacheManager.cancelImageRequest(requestId as PHImageRequestID)
-  // }
-
 }

mobile/lib/platform/thumbnail_api.g.dart

@@ -51,13 +51,14 @@ class ThumbnailApi {
 
   final String pigeonVar_messageChannelSuffix;
 
-  Future<Uint8List> getThumbnail(
+  Future<void> setThumbnailToBuffer(
+    int pointer,
     String assetId, {
     required int width,
     required int height,
   }) async {
     final String pigeonVar_channelName =
-        'dev.flutter.pigeon.immich_mobile.ThumbnailApi.getThumbnail$pigeonVar_messageChannelSuffix';
+        'dev.flutter.pigeon.immich_mobile.ThumbnailApi.setThumbnailToBuffer$pigeonVar_messageChannelSuffix';
     final BasicMessageChannel<Object?> pigeonVar_channel =
         BasicMessageChannel<Object?>(
       pigeonVar_channelName,
@@ -65,7 +66,7 @@ class ThumbnailApi {
       binaryMessenger: pigeonVar_binaryMessenger,
     );
     final Future<Object?> pigeonVar_sendFuture =
-        pigeonVar_channel.send(<Object?>[assetId, width, height]);
+        pigeonVar_channel.send(<Object?>[pointer, assetId, width, height]);
     final List<Object?>? pigeonVar_replyList =
         await pigeonVar_sendFuture as List<Object?>?;
     if (pigeonVar_replyList == null) {
@@ -76,13 +77,8 @@ class ThumbnailApi {
         message: pigeonVar_replyList[1] as String?,
         details: pigeonVar_replyList[2],
       );
-    } else if (pigeonVar_replyList[0] == null) {
-      throw PlatformException(
-        code: 'null-error',
-        message: 'Host platform returned null value for non-null return value.',
-      );
     } else {
-      return (pigeonVar_replyList[0] as Uint8List?)!;
+      return;
     }
   }
 }

mobile/lib/presentation/widgets/images/thumbnail.widget.dart

@@ -1,3 +1,5 @@
+import 'dart:ffi';
+
 import 'package:flutter/material.dart';
 import 'dart:async';
 import 'dart:convert';
@@ -15,12 +17,13 @@ import 'package:immich_mobile/services/api.service.dart';
 import 'package:immich_mobile/utils/image_url_builder.dart';
 import 'package:logging/logging.dart';
 import 'package:thumbhash/thumbhash.dart' as thumbhash;
+import 'package:ffi/ffi.dart';
 
 final log = Logger('ThumbnailWidget');
 
 class Thumbnail extends StatefulWidget {
   final BoxFit fit;
-  final Size size;
+  final ui.Size size;
   final String? blurhash;
   final String? localId;
   final String? remoteId;
@@ -28,7 +31,7 @@ class Thumbnail extends StatefulWidget {
 
   const Thumbnail({
     this.fit = BoxFit.cover,
-    this.size = const Size.square(256),
+    this.size = const ui.Size.square(256),
     this.blurhash,
     this.localId,
     this.remoteId,
@@ -39,7 +42,7 @@ class Thumbnail extends StatefulWidget {
   Thumbnail.fromAsset({
     required Asset asset,
     this.fit = BoxFit.cover,
-    this.size = const Size.square(256),
+    this.size = const ui.Size.square(256),
     this.thumbhashOnly = false,
     super.key,
   })  : blurhash = asset.thumbhash,
@@ -49,7 +52,7 @@ class Thumbnail extends StatefulWidget {
   Thumbnail.fromBaseAsset({
     required BaseAsset? asset,
     this.fit = BoxFit.cover,
-    this.size = const Size.square(256),
+    this.size = const ui.Size.square(256),
     this.thumbhashOnly = false,
     super.key,
   })  : blurhash = switch (asset) {
@@ -188,25 +191,38 @@ class _ThumbnailState extends State<Thumbnail> {
       return null;
     }
     final stopwatch = Stopwatch()..start();
-    final thumb = await _decodeThumbnail(buffer, 256);
+    final thumb = await _decodeThumbnail(buffer, 256, 256);
     stopwatch.stop();
     return thumb;
   }
 
-  Future<ui.Image?> _decodeThumbnail(ImmutableBuffer buffer, int height) async {
+  Future<ui.Image?> _decodeThumbnail(
+    ImmutableBuffer buffer,
+    int width,
+    int height,
+  ) async {
     if (!mounted) {
       buffer.dispose();
       return null;
     }
 
-    final descriptor = await ImageDescriptor.encoded(buffer);
+    final descriptor = ImageDescriptor.raw(
+      buffer,
+      width: width,
+      height: height,
+      pixelFormat: PixelFormat.rgba8888,
+    );
+
     if (!mounted) {
       buffer.dispose();
       descriptor.dispose();
       return null;
     }
 
-    final codec = await descriptor.instantiateCodec(targetHeight: height);
+    final codec = await descriptor.instantiateCodec(
+      targetWidth: width,
+      targetHeight: height,
+    );
 
     if (!mounted) {
       buffer.dispose();
@@ -231,16 +247,24 @@ class _ThumbnailState extends State<Thumbnail> {
     final stopwatch = Stopwatch()..start();
     final localId = widget.localId;
     if (localId != null) {
+      final size = 256 * 256 * 4;
+      final pointer = malloc<Uint8>(size);
       try {
-        final data =
-            await thumbnailApi.getThumbnail(localId, width: 256, height: 256);
+        await thumbnailApi.setThumbnailToBuffer(
+          pointer.address,
+          localId,
+          width: 256,
+          height: 256,
+        );
         stopwatch.stop();
         log.info(
           'Retrieved local image $localId in ${stopwatch.elapsedMilliseconds.toStringAsFixed(2)} ms',
         );
-        return ImmutableBuffer.fromUint8List(data);
+        return ImmutableBuffer.fromUint8List(pointer.asTypedList(size));
       } catch (e) {
         log.warning('Failed to retrieve local image $localId: $e');
+      } finally {
+        malloc.free(pointer);
       }
     }
 

mobile/pigeon/thumbnail_api.dart

@@ -15,23 +15,10 @@ import 'package:pigeon/pigeon.dart';
 @HostApi()
 abstract class ThumbnailApi {
   @async
-  Uint8List getThumbnail(
+  void setThumbnailToBuffer(
+    int pointer,
     String assetId, {
     required int width,
     required int height,
   });
-
-  // @async
-  // int requestThumbnail(
-  //   String assetId, {
-  //   required int width,
-  //   required int height,
-  //   void Function(int requestId) onDone,
-  // });
 }
-
-// @FlutterApi()
-// abstract class PlatformThumbnailApi {
-//   @async
-//   Uint8List? getThumbnail(String assetId, int width, int height);
-// }