C#使用Spire.Pdf添加水印

最近接到的工作 

1.word转PDF

2.PDF添加水印，并控制显示的页数

3.JPG转PDF

 

需要引入 Spire.Pdf    Spire.License 和 System.Drawing

 

接下来上代码

  /// <summary>
        /// 给PDF文件添加水印
        /// </summary>
        /// <param name="pdfPath">需要添加水印的pdf文件路径</param>
        /// <param name="targetPath">添加成功之后的文件路径和文件名</param>
        /// <param name="marks">水印内容</param>
        /// <param name="fromPage">可以从第几页开始看</param>
        /// <param name="toPage">可以看多少页</param>
        /// <returns></returns>
        public static bool PDFAddMark(string pdfPath, string targetPath, string marks, int fromPage = 1, int toPage = 1)
        {
            bool result = false;
            try
            {
                //创建一个新的PDF实例。然后导入PDF文件。 
                Spire.Pdf.PdfDocument pdf = new Spire.Pdf.PdfDocument();
                pdf.LoadFromFile(pdfPath);

                //这里是因为Spire的版本问题 第一页会被添加水印
                PdfPageBase pb = pdf.Pages.Add(); //新增一页
                pdf.Pages.Remove(pb); //去除第一页水印
                
                var a = pdf.Pages.Count;
                if (fromPage > a)
                {
                    fromPage = 1;
                }

                if (fromPage > 1 && toPage < a)
                {
                    for (int i = 0; i < (a - toPage); i++)
                    {
                        pdf.Pages.Remove(pdf.Pages[pdf.Pages.Count - 1]); //去掉后面的页数
                    }

                    for (int i = 1; i < fromPage; i++)
                    {
                        pdf.Pages.Remove(pdf.Pages[0]); //去掉前面的页数
                    }
                }
                else if (fromPage > 1)
                {
                    for (int i = 1; i < fromPage; i++)
                    {
                        pdf.Pages.Remove(pdf.Pages[0]); //去掉前面的页数
                    }
                }
                else if (toPage < a)
                {
                    for (int i = 0; i < (a - toPage); i++)
                    {
                        pdf.Pages.Remove(pdf.Pages[pdf.Pages.Count - 1]); //去掉后面的页数
                    }

                }

                PdfPageBase page = null;
                if (pdf.Pages.Count > 0)
                {
                    for (int i = 0; i < pdf.Pages.Count; i++)
                    {
                        page = pdf.Pages[i];
                        PdfTilingBrush brush = new PdfTilingBrush(new SizeF(page.Canvas.ClientSize.Width / 2, page.Canvas.ClientSize.Height / 3));
                        brush.Graphics.SetTransparency(0.3f);
                        brush.Graphics.Save();
                        brush.Graphics.TranslateTransform(brush.Size.Width / 2, brush.Size.Height / 2);
                        brush.Graphics.RotateTransform(-45);
                        brush.Graphics.DrawString(marks, new Spire.Pdf.Graphics.PdfFont(PdfFontFamily.Helvetica, 24), PdfBrushes.Blue, 0, 0, new PdfStringFormat(PdfTextAlignment.Center));
                        brush.Graphics.Restore();
                        brush.Graphics.SetTransparency(1);
                        page.Canvas.DrawRectangle(brush, new RectangleF(new PointF(0, 0), page.Canvas.ClientSize));
                    }
                    pdf.SaveToFile(targetPath);
                    return true;
                }
                return result;
            }
            catch (Exception ex)
            {
                return false;
            }
        }