ptf转图片

 //private readonly static PdfDocument doc = new PdfDocument();
        //public static Stream PtfToPng(string FileInfo)
        //{
        //byte[] by = Convert.FromBase64String(FileInfo);
        //doc.LoadFromBytes(by);
        //Image bmp = doc.SaveAsImage(0);//默认第一页
        //return ImageToStream(bmp);
        或者
        //遍历PDF每一页
        //for (int i = 0; i < doc.Pages.Count; i++)
        //{
        //    //将PDF页转换成Bitmap图形
        //    Image bmp = doc.SaveAsImage(i);
        //    //将Bitmap图形保存为Png格式的图片
        //    string fileName = string.Format("Page-{0}.png", i + 1);
        //    bmp.Save(fileName, System.Drawing.Imaging.ImageFormat.Png);
        //}
        //}

        /// <summary>
        /// ptf转图片流
        /// </summary>
        /// FileInf base64string
        /// <returns></returns>
        public static Stream PtfToPng(string FileInfo)
        {
            byte[] by = Convert.FromBase64String(FileInfo);
            Stream sm = new MemoryStream(by);
            using (var document = PdfiumViewer.PdfDocument.Load(sm))
            {
                var size = document.PageSizes[0];
                Image ig = document.Render(0, (int)size.Width, (int)size.Height, 300, 300, PdfiumViewer.PdfRenderFlags.Annotations);
                return ImageToStream(ig);
            }
        }

        /// <summary>
        /// 返回图片流
        /// </summary>
        public static Stream ImageToStream(Image img)
        {
            MemoryStream ms = new MemoryStream();
            img.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
            return ms;
        }

private Stream ConvertToImage(Stream sm)
{
    Document doc = new Document(sm);
    if (doc == null)
        Console.Write(doc);
    MemoryStream stream = new MemoryStream();
    Resolution reso = new Resolution(128);
    JpegDevice jpegDevice = new JpegDevice(reso, 100);
    jpegDevice.Process(doc.Pages[1], stream);
    return stream;
        //    //Image img = Image.FromStream(stream);
}