Maintain disk cache for thumbnails by self

lib/core/configuration.dart

@@ -54,6 +54,7 @@ class Configuration {
   String _secretKey;
   FlutterSecureStorage _secureStorage;
   String _tempDirectory;
+  String _thumbnailCacheDirectory;
 
   Future<void> init() async {
     _preferences = await SharedPreferences.getInstance();
@@ -76,6 +77,8 @@ class Configuration {
       _logger.warning(e);
     }
     tempDirectory.createSync(recursive: true);
+    _thumbnailCacheDirectory = (await getTemporaryDirectory()).path + "/thumbnail-cache";
+    io.Directory(_thumbnailCacheDirectory).createSync(recursive: true);
     if (!_preferences.containsKey(tokenKey)) {
       await _secureStorage.deleteAll();
     } else {
@@ -367,6 +370,10 @@ class Configuration {
     return _tempDirectory;
   }
 
+  String getThumbnailCacheDirectory() {
+    return _thumbnailCacheDirectory;
+  }
+
   bool hasConfiguredAccount() {
     return getToken() != null && _key != null;
   }

lib/utils/file_util.dart

@@ -206,5 +206,11 @@ void clearCache(File file) {
   } else {
     DefaultCacheManager().removeFile(file.getDownloadUrl());
   }
-  ThumbnailCacheManager.instance.removeFile(file.getThumbnailUrl());
+  final cachedThumbnail = io.File(
+      Configuration.instance.getThumbnailCacheDirectory() +
+          "/" +
+          file.uploadedFileID.toString());
+  if (cachedThumbnail.existsSync()) {
+    cachedThumbnail.deleteSync();
+  }
 }

lib/utils/thumbnail_util.dart

@@ -7,7 +7,6 @@ import 'package:dio/dio.dart';
 import 'package:flutter_sodium/flutter_sodium.dart';
 import 'package:logging/logging.dart';
 import 'package:photos/core/cache/thumbnail_cache.dart';
-import 'package:photos/core/cache/thumbnail_cache_manager.dart';
 import 'package:photos/core/configuration.dart';
 import 'package:photos/core/constants.dart';
 import 'package:photos/core/errors.dart';
@@ -16,6 +15,8 @@ import 'package:photos/models/file.dart';
 import 'package:photos/utils/crypto_util.dart';
 import 'package:photos/utils/file_util.dart';
 
+import 'dart:io' as io;
+
 final _logger = Logger("ThumbnailUtil");
 final _map = LinkedHashMap<int, FileDownloadItem>();
 final _queue = Queue<int>();
@@ -30,10 +31,12 @@ class FileDownloadItem {
 }
 
 Future<Uint8List> getThumbnailFromServer(File file) async {
-  return ThumbnailCacheManager.instance
-      .getFileFromCache(file.getThumbnailUrl())
-      .then((info) {
-    if (info == null) {
+  final cachedThumbnail = getCachedThumbnail(file);
+  if (cachedThumbnail.existsSync()) {
+    final data = cachedThumbnail.readAsBytesSync();
+    ThumbnailLruCache.put(file, data);
+    return data;
+  }
   if (!_map.containsKey(file.uploadedFileID)) {
     if (_queue.length == kMaximumConcurrentDownloads) {
       final id = _queue.removeFirst();
@@ -41,8 +44,7 @@ Future<Uint8List> getThumbnailFromServer(File file) async {
       item.cancelToken.cancel();
       item.completer.completeError(RequestCancelledError());
     }
-        final item =
-            FileDownloadItem(file, Completer<Uint8List>(), CancelToken());
+    final item = FileDownloadItem(file, Completer<Uint8List>(), CancelToken());
     _map[file.uploadedFileID] = item;
     _queue.add(file.uploadedFileID);
     _downloadItem(item);
@@ -50,11 +52,6 @@ Future<Uint8List> getThumbnailFromServer(File file) async {
   } else {
     return _map[file.uploadedFileID].completer.future;
   }
-    } else {
-      ThumbnailLruCache.put(file, info.file.readAsBytesSync());
-      return info.file.readAsBytes();
-    }
-  });
 }
 
 void removePendingGetThumbnailRequestIfAny(File file) {
@@ -110,12 +107,11 @@ Future<void> _downloadAndDecryptThumbnail(FileDownloadItem item) async {
     data = await compressThumbnail(data);
   }
   ThumbnailLruCache.put(item.file, data);
-  ThumbnailCacheManager.instance.putFile(
-    file.getThumbnailUrl(),
-    data,
-    eTag: file.getThumbnailUrl(),
-    maxAge: Duration(days: 365),
-  );
+  final cachedThumbnail = getCachedThumbnail(item.file);
+  if (cachedThumbnail.existsSync()) {
+    cachedThumbnail.deleteSync();
+  }
+  cachedThumbnail.writeAsBytes(data);
   if (_map.containsKey(file.uploadedFileID)) {
     try {
       item.completer.complete(data);
@@ -125,3 +121,9 @@ Future<void> _downloadAndDecryptThumbnail(FileDownloadItem item) async {
     }
   }
 }
+
+io.File getCachedThumbnail(File file) {
+  final thumbnailCacheDirectory =
+      Configuration.instance.getThumbnailCacheDirectory();
+  return io.File(thumbnailCacheDirectory + "/" + file.uploadedFileID.toString());
+}