61 lines
2.2 KiB
Dart
61 lines
2.2 KiB
Dart
import 'dart:io';
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import 'package:flutter/services.dart';
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import 'package:path/path.dart' as path;
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import 'package:path_provider/path_provider.dart';
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import '../utils/app_logger.dart';
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/// Utility class for loading font assets for libass subtitle rendering.
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///
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/// Extracts font files from Flutter assets to the app's cache directory to ensure
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/// comprehensive Unicode coverage (including CJK characters) for subtitles.
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class SubtitleFontLoader {
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static const String _fontAssetPath = 'assets/go-noto-current-regular.ttf';
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static const String _fontName = 'Go Noto Current-Regular';
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/// In-memory cache of the resolved font directory. The filesystem work
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/// (temp dir lookup, existence checks, asset extraction) is idempotent per
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/// process — caching the result skips ~20ms on every subsequent Player
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/// instantiation.
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static Future<String?>? _cachedFontDir;
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/// Loads the subtitle font from assets to the cache directory.
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/// Returns the directory path containing the font file.
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static Future<String?> loadSubtitleFont() {
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return _cachedFontDir ??= _loadSubtitleFontOnce();
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}
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static Future<String?> _loadSubtitleFontOnce() async {
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try {
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// Get the app's cache directory
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final cacheDir = await getTemporaryDirectory();
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final fontDir = Directory(path.join(cacheDir.path, 'subtitle_fonts'));
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// Create fonts directory if it doesn't exist
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if (!await fontDir.exists()) {
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await fontDir.create(recursive: true);
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}
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final fontFile = File(path.join(fontDir.path, 'go-noto-current-regular.ttf'));
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// Load font from assets and write to cache if it doesn't exist
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if (!await fontFile.exists()) {
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final fontData = await rootBundle.load(_fontAssetPath);
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await fontFile.writeAsBytes(fontData.buffer.asUint8List());
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}
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return fontDir.path;
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} catch (e, st) {
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// Return null if font loading fails - libass will fall back gracefully
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appLogger.w('Failed to load subtitle font', error: e, stackTrace: st);
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return null;
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}
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}
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/// Returns the font name to be used with libass.
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static String get fontName => _fontName;
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/// Returns the font asset path.
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static String get fontAssetPath => _fontAssetPath;
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}
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