优化备份卡顿问题

lib/pages/home/main_content_page.dart

@@ -426,6 +426,7 @@ class _CloudSheetContentState extends State<_CloudSheetContent> {
     if (direction == SyncDirection.upload) {
       // 上传：先打包，再上传
       setState(() => _syncStep = '正在打包数据...');
+      await Future.delayed(Duration.zero); // 让 UI 先渲染进度动画
       final exportResult = await WebDAVService.instance.exportLocalData();
       if (!exportResult.success || exportResult.zipPath == null) {
         if (mounted) {
@@ -436,6 +437,7 @@ class _CloudSheetContentState extends State<_CloudSheetContent> {
       }
       if (!mounted) return;
       setState(() => _syncStep = '正在上传到云端...');
+      await Future.delayed(Duration.zero); // 让 UI 先渲染进度动画
       final result = await WebDAVService.instance.uploadExportedData(exportResult);
       if (result.success && result.needReload && mounted) {
         final provider = context.read<AppProvider>();
@@ -457,6 +459,7 @@ class _CloudSheetContentState extends State<_CloudSheetContent> {
     } else {
       // 下载
       setState(() => _syncStep = '正在从云端下载...');
+      await Future.delayed(Duration.zero); // 让 UI 先渲染进度动画
       final config = await WebDAVService.instance.getConfig();
       if (config == null) {
         if (mounted) {

lib/pages/sync/webdav_sync_page.dart

@@ -131,6 +131,7 @@ class _WebDAVSyncPageState extends State<WebDAVSyncPage> {
       if (_syncDirection == SyncDirection.upload) {
         // 上传：先打包再上传，分步显示
         setState(() => _syncStep = '正在打包数据...');
+        await Future.delayed(Duration.zero); // 让 UI 先渲染进度动画
         final exportResult = await WebDAVService.instance.exportLocalData();
         if (!exportResult.success || exportResult.zipPath == null) {
           if (mounted) {
@@ -141,10 +142,12 @@ class _WebDAVSyncPageState extends State<WebDAVSyncPage> {
         }
         if (!mounted) return;
         setState(() => _syncStep = '正在上传到云端...');
+        await Future.delayed(Duration.zero); // 让 UI 先渲染进度动画
         result = await WebDAVService.instance.uploadExportedData(exportResult);
       } else {
         // 下载
         setState(() => _syncStep = '正在从云端下载...');
+        await Future.delayed(Duration.zero); // 让 UI 先渲染进度动画
         result = await WebDAVService.instance.syncData(direction: SyncDirection.download);
       }
 

lib/services/sync/backup_service.dart

@@ -19,8 +19,9 @@ class BackupService {
 
   // ─── 共享导出逻辑 ─────────────────────────────────────
 
-  /// 收集所有表数据和图片，构建 ZIP 字节
+  /// 收集所有表数据和图片，构建 ZIP 文件
   Future<_ExportData> _buildExportData() async {
+    // 阶段1：主线程收集数据（DB 查询、SharedPreferences 需主线程）
     final db = await DatabaseHelper.instance.database;
 
     final movies = await db.query('movies');
@@ -109,69 +110,25 @@ class BackupService {
       },
     };
 
-    // 创建 ZIP（逐文件写入磁盘，避免全部加载到内存）
+    // 阶段2：后台 isolate 执行 JSON 编码 + ZIP 压缩（避免阻塞主线程动画）
     final tempDir = await getTemporaryDirectory();
-    final tempZipPath = path.join(tempDir.path, 'mooknote_backup_temp.zip');
+    final appDir = await getApplicationDocumentsDirectory();
-    final encoder = ZipFileEncoder();
-    encoder.create(tempZipPath);
 
-    try {
+    final result = await compute(_buildZipInIsolate, _ZipComputeParams(
-      // data.json
+      backupData: backupData,
-      final jsonString = const JsonEncoder.withIndent('  ').convert(backupData);
+      imagePaths: imagePaths.toList(),
-      final jsonBytes = Uint8List.fromList(utf8.encode(jsonString));
+      tempDirPath: tempDir.path,
-      final dataFile = File(path.join(tempDir.path, 'mooknote_data.json'));
+      appDirPath: appDir.path,
-      await dataFile.writeAsBytes(jsonBytes);
+    ));
-      encoder.addFile(dataFile, 'data.json');
-      await dataFile.delete();
 
-      int imageCount = 0;
+    return _ExportData(
-      final appDir = await getApplicationDocumentsDirectory();
+      zipPath: result.zipPath,
-      final imagesRoot = path.join(appDir.path, 'images');
+      movieCount: movies.length,
-
+      bookCount: books.length,
-      for (final imagePath in imagePaths) {
+      noteCount: notes.length,
-        final file = File(imagePath);
+      imageCount: result.imageCount,
-        if (await file.exists()) {
+      epubCount: result.epubCount,
-          String relativePath;
+    );
-          if (imagePath.startsWith(imagesRoot)) {
-            relativePath = imagePath.substring(imagesRoot.length + 1);
-          } else {
-            relativePath = path.basename(imagePath);
-          }
-          encoder.addFile(file, 'images/$relativePath');
-          imageCount++;
-        }
-      }
-
-      // 收集 epub_books 目录下的 epub 文件
-      int epubCount = 0;
-      final epubRoot = path.join(appDir.path, 'epub_books');
-      final epubDir = Directory(epubRoot);
-      if (await epubDir.exists()) {
-        await for (final entity in epubDir.list(recursive: true)) {
-          if (entity is File) {
-            final relativePath = entity.path.substring(epubRoot.length + 1);
-            encoder.addFile(entity, 'epub_books/$relativePath');
-            epubCount++;
-          }
-        }
-      }
-
-      encoder.close();
-
-      // 返回 zip 文件路径，不再读入内存
-      return _ExportData(
-        zipPath: tempZipPath,
-        movieCount: movies.length,
-        bookCount: books.length,
-        noteCount: notes.length,
-        imageCount: imageCount,
-        epubCount: epubCount,
-      );
-    } catch (e) {
-      encoder.close();
-      try { await File(tempZipPath).delete(); } catch (_) {}
-      rethrow;
-    }
   }
 
   // ─── 手动导出 ─────────────────────────────────────────
@@ -912,3 +869,83 @@ class ImportResult {
     return stats!.entries.map((e) => '${e.key}: ${e.value}').join('，');
   }
 }
+
+// ─── compute isolate 参数和函数 ──────────────────────────
+
+class _ZipComputeParams {
+  final Map<String, dynamic> backupData;
+  final List<String> imagePaths;
+  final String tempDirPath;
+  final String appDirPath;
+
+  _ZipComputeParams({
+    required this.backupData,
+    required this.imagePaths,
+    required this.tempDirPath,
+    required this.appDirPath,
+  });
+}
+
+class _ZipComputeResult {
+  final String? zipPath;
+  final int imageCount;
+  final int epubCount;
+
+  _ZipComputeResult({this.zipPath, required this.imageCount, required this.epubCount});
+}
+
+/// 在后台 isolate 中执行 JSON 编码 + ZIP 压缩，避免阻塞主线程
+_ZipComputeResult _buildZipInIsolate(_ZipComputeParams params) {
+  final tempZipPath = path.join(params.tempDirPath, 'mooknote_backup_temp.zip');
+  final encoder = ZipFileEncoder();
+  encoder.create(tempZipPath);
+
+  try {
+    // data.json
+    final jsonString = const JsonEncoder.withIndent('  ').convert(params.backupData);
+    final jsonBytes = Uint8List.fromList(utf8.encode(jsonString));
+    final dataFile = File(path.join(params.tempDirPath, 'mooknote_data.json'));
+    dataFile.writeAsBytesSync(jsonBytes);
+    encoder.addFile(dataFile, 'data.json');
+    dataFile.deleteSync();
+
+    int imageCount = 0;
+    final imagesRoot = path.join(params.appDirPath, 'images');
+
+    for (final imagePath in params.imagePaths) {
+      final file = File(imagePath);
+      if (file.existsSync()) {
+        String relativePath;
+        if (imagePath.startsWith(imagesRoot)) {
+          relativePath = imagePath.substring(imagesRoot.length + 1);
+        } else {
+          relativePath = path.basename(imagePath);
+        }
+        encoder.addFile(file, 'images/$relativePath');
+        imageCount++;
+      }
+    }
+
+    // 收集 epub_books 目录下的 epub 文件
+    int epubCount = 0;
+    final epubRoot = path.join(params.appDirPath, 'epub_books');
+    final epubDir = Directory(epubRoot);
+    if (epubDir.existsSync()) {
+      for (final entity in epubDir.listSync(recursive: true)) {
+        if (entity is File) {
+          final relativePath = entity.path.substring(epubRoot.length + 1);
+          encoder.addFile(entity, 'epub_books/$relativePath');
+          epubCount++;
+        }
+      }
+    }
+
+    encoder.close();
+
+    return _ZipComputeResult(zipPath: tempZipPath, imageCount: imageCount, epubCount: epubCount);
+  } catch (e) {
+    encoder.close();
+    try { File(tempZipPath).deleteSync(); } catch (_) {}
+    rethrow;
+  }
+}