Initial flame_lua_runtime package

lib/runtime/resources/game_resource_cache.dart

@@ -0,0 +1,66 @@
+part of 'game_resource_manager.dart';
+
+extension _GameResourceManagerCache on GameResourceManager {
+  void _touch(_ImageResourceRecord record) {
+    record.lastUsed = ++_accessCounter;
+  }
+
+  void _enforceImageBudget() {
+    while (_isOverBudget()) {
+      final victim = _leastRecentlyUsedEvictableImage();
+      if (victim == null || !_removeImageRecord(victim)) {
+        return;
+      }
+    }
+  }
+
+  bool _isOverBudget() {
+    final maxBytes = _maxCacheBytes;
+    final maxEntries = _maxCacheEntries;
+    return (maxBytes != null && _cacheBytes > maxBytes) ||
+        (maxEntries != null && _readyImageCount > maxEntries);
+  }
+
+  int get _readyImageCount => _images.values
+      .where((record) => record.state == GameResourceState.ready)
+      .length;
+
+  String? _leastRecentlyUsedEvictableImage() {
+    String? victimPath;
+    _ImageResourceRecord? victim;
+    for (final entry in _images.entries) {
+      final record = entry.value;
+      if (record.state != GameResourceState.ready || record.refCount > 0) {
+        continue;
+      }
+      if (victim == null || record.lastUsed < victim.lastUsed) {
+        victim = record;
+        victimPath = entry.key;
+      }
+    }
+    return victimPath;
+  }
+
+  void _releaseCachedImages() {
+    _loadLimiter.clearPending();
+    for (final path in _images.keys.toList(growable: false)) {
+      _removeImageRecord(path);
+    }
+  }
+
+  bool _removeImageRecord(String path) {
+    final record = _images.remove(path);
+    if (record == null) {
+      return false;
+    }
+    record.state = GameResourceState.disposed;
+    _cacheBytes -= record.estimatedBytes;
+    if (_cacheBytes < 0) {
+      _cacheBytes = 0;
+    }
+    record.image?.dispose();
+    record.image = null;
+    record.inflight = null;
+    return true;
+  }
+}