internal static extern ThumbnailExtractorError Cancel(ThumbnailExtractorHandle handle, string requestId);
 internal static extern ThumbnailExtractorError SetSize(ThumbnailExtractorHandle handle, int width, int height);
 internal static extern ThumbnailExtractorError Extract(ThumbnailExtractorHandle handle,
                                                        ThumbnailExtractCallback callback, IntPtr userData, out IntPtr requestId);
 internal static extern ThumbnailExtractorError SetPath(ThumbnailExtractorHandle handle, string path);
 internal static extern ThumbnailExtractorError Create(out ThumbnailExtractorHandle handle);