PDF上加骑缝章

using iTextSharp.text;
using iTextSharp.text.pdf;
using System;
using System.IO;

class Program
{
    static void Main()
    {
        try
        {
            // 输入 PDF 文件路径
            string inputPdfPath = @"path/to/your/input.pdf";
            // 印章图片路径
            string sealImagePath = @"path/to/your/seal.png";
            // 输出 PDF 文件路径
            string outputPdfPath = @"path/to/your/output.pdf";

            AddRidingSealToPdf(inputPdfPath, sealImagePath, outputPdfPath);
            Console.WriteLine("骑缝章添加成功！");
        }
        catch (Exception ex)
        {
            Console.WriteLine("发生错误: " + ex.Message);
        }
    }

    static void AddRidingSealToPdf(string inputPdfPath, string sealImagePath, string outputPdfPath)
    {
        using (PdfReader reader = new PdfReader(inputPdfPath))
        {
            using (PdfStamper stamper = new PdfStamper(reader, new FileStream(outputPdfPath, FileMode.Create)))
            {
                int pageCount = reader.NumberOfPages;
                // 加载印章图片
                Image sealImage = Image.GetInstance(sealImagePath);
                float sealWidth = sealImage.Width / pageCount;
                float sealHeight = sealImage.Height;

                for (int i = 1; i <= pageCount; i++)
                {
                    PdfContentByte contentByte = stamper.GetOverContent(i);
                    // 计算当前页要显示的印章部分的起始位置
                    float startX = (i - 1) * sealWidth;
                    // 创建一个矩形来裁剪印章图片
                    Rectangle rect = new Rectangle(startX, 0, startX + sealWidth, sealHeight);
                    sealImage.SetAbsolutePosition(0, 0);
                    sealImage.ScaleAbsolute(sealWidth, sealHeight);
                    // 裁剪印章图片
                    sealImage.Alignment = Image.UNDERLYING;
                    sealImage.Crop = rect;
                    contentByte.AddImage(sealImage);
                }
            }
        }
    }
}