/// <summary>
/// 拼接文档图片的下载地址
/// </summary>
/// <param name="urlPrefix">文档信息中的url前缀</param>
/// <param name="imgType">文档转换的图片类型</param>
/// <param name="quality">需要的图片清晰度</param>
/// <param name="pageNum">图片页码（从1开始计算）</param>
/// <returns></returns>
public static string GetPageUrl(string urlPrefix, NIMDocTranscodingImageType imgType, NIMDocTranscodingQuality quality, int pageNum)
{
var ptr = DocTransNativeMethods.nim_doctrans_get_page_url(urlPrefix, imgType, quality, pageNum);
NimUtility.Utf8StringMarshaler marshaler = new NimUtility.Utf8StringMarshaler();
string url = marshaler.MarshalNativeToManaged(ptr) as string;
GlobalAPI.FreeBuffer(ptr);
return(url);
}
internal static extern IntPtr nim_doctrans_get_page_url(
[MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(NimUtility.Utf8StringMarshaler))] string urlPrefix,
NIMDocTranscodingImageType img_type, NIMDocTranscodingQuality quality, int page_num);