Class TextureLoader

packages/asset-system/src/loaders/TextureLoader.ts:44–117

 * 纹理加载器实现
 */
export class TextureLoader implements IAssetLoader<ITextureAsset> {
    readonly supportedType = AssetType.Texture;
    readonly supportedExtensions = ['.png', '.jpg', '.jpeg', '.gif', '.webp', '.bmp'];
    readonly contentType: AssetContentType = 'image';

    private static _nextTextureId = 1;

    /**
     * Reset texture ID counter
     * 重置纹理 ID 计数器
     *
     * This should be called when restoring scene snapshots to ensure
     * textures start with fresh IDs.
     * 在恢复场景快照时应调用此方法，以确保纹理从新 ID 开始。
     */
    static resetTextureIdCounter(): void {
        TextureLoader._nextTextureId = 1;
    }

    /**
     * Parse texture from image content.
     * 从图片内容解析纹理。
     */
    async parse(content: IAssetContent, context: IAssetParseContext): Promise<ITextureAsset> {
        if (!content.image) {
            throw new Error('Texture content is empty');
        }

        const image = content.image;

        // Read sprite settings from import settings
        // 从导入设置读取 sprite 设置
        const importSettings = context.metadata.importSettings as Record<string, unknown> | undefined;
        const spriteSettings = importSettings?.spriteSettings as ISpriteSettings | undefined;

        const textureAsset: ITextureAsset = {
            textureId: TextureLoader._nextTextureId++,
            width: image.width,
            height: image.height,
            format: 'rgba',
            hasMipmaps: false,
            data: image,
            // Include sprite settings if available
            // 如果有则包含 sprite 设置
            sliceBorder: spriteSettings?.sliceBorder,
            pivot: spriteSettings?.pivot
        };

        // Upload to GPU if bridge exists.
        const bridge = getEngineBridge();
        if (bridge?.loadTexture) {
            await bridge.loadTexture(textureAsset.textureId, context.metadata.path);
        }

        return textureAsset;
    }

    /**