优化项目结构

lib/services/font_download_manager.dart

@@ -0,0 +1,174 @@
+import 'dart:io';
+import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
+import 'package:path/path.dart' as path;
+import 'package:path_provider/path_provider.dart';
+
+/// 本地字体扫描与加载管理器
+///
+/// 扫描用户指定目录下的字体文件，通过 FontLoader 动态注册到 Flutter。
+class FontDownloadManager {
+  static final FontDownloadManager _instance = FontDownloadManager._internal();
+  factory FontDownloadManager() => _instance;
+  FontDownloadManager._internal();
+
+  /// 已加载的字体 family 集合（避免重复注册）
+  final Set<String> _loadedFonts = {};
+
+  /// 支持的字体文件扩展名
+  static const List<String> _fontExtensions = ['.ttf', '.otf', '.ttc'];
+
+  /// 扫描指定目录下的字体文件
+  Future<List<FontFileInfo>> scanFontDirectory(String dirPath) async {
+    final dir = Directory(dirPath);
+    if (!await dir.exists()) {
+      debugPrint('[FontScan] 目录不存在: $dirPath');
+      return [];
+    }
+
+    final fonts = <FontFileInfo>[];
+    try {
+      await for (final entity in dir.list(recursive: true)) {
+        if (entity is File) {
+          final ext = path.extension(entity.path).toLowerCase();
+          if (_fontExtensions.contains(ext)) {
+            final fileName = path.basename(entity.path);
+            fonts.add(FontFileInfo(
+              path: entity.path,
+              fileName: fileName,
+              displayName: _formatFontName(fileName),
+            ));
+          }
+        }
+      }
+    } catch (e) {
+      debugPrint('[FontScan] 扫描异常: $e');
+    }
+    // 按文件名排序
+    fonts.sort((a, b) => a.fileName.compareTo(b.fileName));
+    debugPrint('[FontScan] 扫描完成: $dirPath, 找到 ${fonts.length} 个字体文件');
+    return fonts;
+  }
+
+  /// 从字体文件名生成显示名称
+  String _formatFontName(String fileName) {
+    // 移除扩展名
+    var name = path.basenameWithoutExtension(fileName);
+    // 替换常见分隔符为空格
+    name = name.replaceAll('_', ' ').replaceAll('-', ' ');
+    // 首字母大写
+    return name.split(' ').map((w) {
+      if (w.isEmpty) return w;
+      return w[0].toUpperCase() + w.substring(1).toLowerCase();
+    }).join(' ');
+  }
+
+  /// 加载指定字体文件
+  ///
+  /// [filePath] 字体文件完整路径
+  /// [family] 可选的字体 family 名称（默认使用文件名）
+  ///
+  /// 返回加载成功后的 family 名称
+  Future<String?> loadFontFile(String filePath, {String? family}) async {
+    final file = File(filePath);
+    if (!await file.exists()) return null;
+
+    final fileName = path.basename(filePath);
+    final familyName = family ?? path.basenameWithoutExtension(fileName);
+
+    // 已加载过，直接返回
+    if (_loadedFonts.contains(familyName)) {
+      return familyName;
+    }
+
+    try {
+      final bytes = await file.readAsBytes();
+      final loader = FontLoader(familyName);
+      loader.addFont(Future.value(ByteData.sublistView(bytes)));
+      await loader.load();
+      _loadedFonts.add(familyName);
+      debugPrint('[FontDownload] 字体加载成功: $familyName');
+      return familyName;
+    } catch (e) {
+      debugPrint('[FontDownload] 字体加载失败: $familyName, error=$e');
+      return null;
+    }
+  }
+
+  /// 预加载已缓存的字体（应用启动时调用）
+  Future<void> preloadCachedFont(String family) async {
+    if (family.isEmpty) return;
+    if (_loadedFonts.contains(family)) return;
+
+    // 尝试从默认字体目录加载
+    try {
+      final fontDir = await _getFontDir();
+      final file = File(path.join(fontDir.path, '$family.ttf'));
+      if (await file.exists()) {
+        await loadFontFile(file.path, family: family);
+        return;
+      }
+      // 尝试其他扩展名
+      for (final ext in ['.otf', '.ttc']) {
+        final file2 = File(path.join(fontDir.path, '$family$ext'));
+        if (await file2.exists()) {
+          await loadFontFile(file2.path, family: family);
+          return;
+        }
+      }
+    } catch (e) {
+      debugPrint('[FontDownload] 预加载失败: $family, error=$e');
+    }
+  }
+
+  /// 获取字体缓存目录
+  Future<Directory> _getFontDir() async {
+    if (Platform.isAndroid) {
+      final fontDir = Directory('/sdcard/Documents/mooknote/fonts');
+      if (!await fontDir.exists()) {
+        await fontDir.create(recursive: true);
+      }
+      return fontDir;
+    }
+    // iOS / 桌面端 fallback
+    final appDir = await getApplicationDocumentsDirectory();
+    final fontDir = Directory(path.join(appDir.path, 'fonts'));
+    if (!await fontDir.exists()) {
+      await fontDir.create(recursive: true);
+    }
+    return fontDir;
+  }
+
+  /// 清理所有下载的字体缓存
+  Future<void> clearAllCache() async {
+    try {
+      final fontDir = await _getFontDir();
+      if (await fontDir.exists()) {
+        await for (final entity in fontDir.list()) {
+          if (entity is File) {
+            try {
+              await entity.delete();
+            } catch (_) {}
+          }
+        }
+      }
+      _loadedFonts.clear();
+      debugPrint('[FontDownload] 字体缓存已清理');
+    } catch (e) {
+      debugPrint('[FontDownload] 清理缓存失败: $e');
+    }
+  }
+}
+
+/// 字体文件信息
+class FontFileInfo {
+  final String path;
+  final String fileName;
+  final String displayName;
+
+  FontFileInfo({
+    required this.path,
+    required this.fileName,
+    required this.displayName,
+  });
+}