ds8-solution-pro/ds-wms-service/DS.WMS.Core/Utils/PDFUtil.cs

using iText.Kernel.Pdf;

namespace DS.Module.Core.Utils
{
    /// <summary>
    /// PDF处理工具类
    /// </summary>
    public static class PDFUtil
    {
        public static async void AddStrampAsync(this Stream stream)
        {
            ArgumentNullException.ThrowIfNull(stream, nameof(stream));

            if (!stream.CanRead)
                throw new ArgumentException("流不支持读取", nameof(stream));

            var pdfStream = stream;
            if (!stream.CanWrite)
            {
                pdfStream = new MemoryStream();
                await stream.CopyToAsync(pdfStream);
            }

            var pdfReader = new PdfReader(stream);

        }
    }
}