nuget安装iTextSharp：
static void MergePDF(string picPath,string pdfPath)
{
string[] picFileNames=Directory.GetFiles(picPath, "*");
List<string> fileNames = picFileNames.ToList();
fileNames.Sort((l,r)=> {
int lnum = int.Parse(Path.GetFileName(l).Replace(".jpg",""));
int rnum = int.Parse(Path.GetFileName(r).Replace(".jpg",""));
return lnum.CompareTo(rnum);
});
Document document = new Document(new Rectangle(2100,1488));//设定pdf的大小
PdfWriter.GetInstance(document, new FileStream(pdfPath, FileMode.Create));
document.Open();
foreach (string jpgPath in fileNames)
{
Image jpgImage = Image.GetInstance(jpgPath);
jpgImage.ScaleToFit(document.PageSize.Width, document.PageSize.Height);//调整图片的大小
document.Add(jpgImage);
}
document.Close();
}