feat: add AssetManager core module with ref counting

src/core/AssetManager.ts

@@ -0,0 +1,64 @@
+import { Assets, type AssetsBundle } from "pixi.js";
+import { logger } from "./Logger";
+
+class AssetManager {
+  private referenceCounts: Map<string, number> = new Map();
+
+  async init(): Promise<void> {
+    await Assets.init({ manifest: "/manifest.json" });
+    logger.debug("AssetManager initialized");
+  }
+
+  async loadBundle(
+    name: string,
+    onProgress?: (progress: number) => void
+  ): Promise<AssetsBundle> {
+    // 已经加载过，增加引用计数
+    if (this.referenceCounts.has(name)) {
+      const count = this.referenceCounts.get(name)! + 1;
+      this.referenceCounts.set(name, count);
+      logger.debug(`AssetManager: reuse bundle "${name}", refCount = ${count}`);
+      onProgress?.(1);
+      return Assets.getBundle(name);
+    }
+
+    // 首次加载
+    logger.debug(`AssetManager: loading bundle "${name}"`);
+    const bundle = await Assets.loadBundle(name, onProgress);
+    this.referenceCounts.set(name, 1);
+    return bundle;
+  }
+
+  async unloadBundle(name: string): Promise<void> {
+    if (!this.referenceCounts.has(name)) {
+      logger.warn(`AssetManager: unloading unloaded bundle "${name}"`);
+      return;
+    }
+
+    const count = this.referenceCounts.get(name)! - 1;
+    this.referenceCounts.set(name, count);
+
+    if (count <= 0) {
+      logger.debug(`AssetManager: unloading bundle "${name}"`);
+      await Assets.unloadBundle(name);
+      this.referenceCounts.delete(name);
+    } else {
+      logger.debug(`AssetManager: decrease refCount for "${name}" to ${count}`);
+    }
+  }
+
+  isLoaded(name: string): boolean {
+    return this.referenceCounts.has(name) && this.referenceCounts.get(name)! > 0;
+  }
+
+  getRefCount(name: string): number {
+    return this.referenceCounts.get(name) ?? 0;
+  }
+
+  clearAll(): void {
+    this.referenceCounts.clear();
+  }
+}
+
+export const assetManager = new AssetManager();
+export default assetManager;