feat(mobile): platform image providers (#20927)

* platform image providers

* use key

* fix cache manager

* more logs, cancel on dispose instead

* split into separate files

* fix saving to cache

* cancel multi-stage provider

* refactored `getInitialImage`

* only wait for disposal for full images

* cached image works

* formatting

* lower asset viewer ram usage

---------

Co-authored-by: Alex <alex.tran1502@gmail.com>

mobile/lib/infrastructure/loaders/image_request.dart

@@ -0,0 +1,81 @@
+import 'dart:async';
+import 'dart:ffi';
+import 'dart:io';
+import 'dart:ui' as ui;
+
+import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
+import 'package:flutter/foundation.dart';
+import 'package:ffi/ffi.dart';
+import 'package:immich_mobile/domain/models/asset/base_asset.model.dart';
+import 'package:immich_mobile/providers/image/cache/remote_image_cache_manager.dart';
+import 'package:immich_mobile/providers/infrastructure/platform.provider.dart';
+import 'package:logging/logging.dart';
+
+part 'local_image_request.dart';
+part 'thumbhash_image_request.dart';
+part 'remote_image_request.dart';
+
+abstract class ImageRequest {
+  static int _nextRequestId = 0;
+
+  final int requestId = _nextRequestId++;
+  bool _isCancelled = false;
+
+  get isCancelled => _isCancelled;
+
+  ImageRequest();
+
+  Future<ImageInfo?> load(ImageDecoderCallback decode, {double scale = 1.0});
+
+  void cancel() {
+    if (_isCancelled) {
+      return;
+    }
+    _isCancelled = true;
+    return _onCancelled();
+  }
+
+  void _onCancelled();
+
+  Future<ui.FrameInfo?> _fromPlatformImage(Map<String, int> info) async {
+    final address = info['pointer'];
+    if (address == null) {
+      if (!kReleaseMode) {
+        debugPrint('Platform image request for $requestId was cancelled');
+      }
+      return null;
+    }
+
+    final pointer = Pointer<Uint8>.fromAddress(address);
+    try {
+      if (_isCancelled) {
+        return null;
+      }
+
+      final actualWidth = info['width']!;
+      final actualHeight = info['height']!;
+      final actualSize = actualWidth * actualHeight * 4;
+
+      final buffer = await ImmutableBuffer.fromUint8List(pointer.asTypedList(actualSize));
+      if (_isCancelled) {
+        return null;
+      }
+
+      final descriptor = ui.ImageDescriptor.raw(
+        buffer,
+        width: actualWidth,
+        height: actualHeight,
+        pixelFormat: ui.PixelFormat.rgba8888,
+      );
+      final codec = await descriptor.instantiateCodec();
+      if (_isCancelled) {
+        return null;
+      }
+
+      return await codec.getNextFrame();
+    } finally {
+      malloc.free(pointer);
+    }
+  }
+}