图片转pdf

引用 iTextSharp dll itextsharp.dll(版本5.5.13.3) 、 Spire.Pdf.dll（版本9.2.6.0）

/// <summary>
        /// 图片转pdf
        /// </summary>
        /// <param name="imgFile">要转换的图片的路径(含后缀)</param>
        /// <param name="pdfPath">转成后的文件地址和文件名</param>] 
        public static void ImageToPDF(string imgFile, string pdfPath)
        {
            int p = 0;
            int p1 = 0;
            var document = new Document(PageSize.A4, p1, p1, p1, p1);
            using (var stream = new FileStream(pdfPath, FileMode.Create, FileAccess.Write, FileShare.None))
            {
                iTextSharp.text.pdf.PdfWriter.GetInstance(document, stream);
                document.Open();
                using (var imageStream = new FileStream(imgFile, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
                {
                    var image = iTextSharp.text.Image.GetInstance(imageStream);
                    //根据实际需求，换算图片大小
                    float imageWidth = image.Width / 1.38f;
                    float imageHeight = image.Height/ 1.305f;
                    image.ScaleToFit(imageWidth, imageHeight);
                    document.SetPageSize(new iTextSharp.text.Rectangle(0, 0, imageWidth, imageHeight));
                    image.Alignment = Element.ALIGN_MIDDLE;
                    document.NewPage();
                    document.Add(image);
                }
                document.Close();
            }
        }