安装iTextSharp
/// <summary>
/// PDF添加文字水印
/// </summary>
/// <param name="source"></param>
/// <param name="waterMark">水印文字内容</param>
/// <param name="markOpacity">水印透明度,默认0.15f</param>
/// <param name="waterMark">水印在文字上方或下方:上方1;其它下方</param>
/// <returns></returns>
public static byte[] SetPDFWaterMark(byte[] source, string waterMark, float markOpacity = 0.15f, int OverContent = 1)
{
byte[] rtnContent = null;
PdfReader pdfReader = null;
PdfStamper pdfStamper = null;
try
{
pdfReader = new PdfReader(source);
using (MemoryStream stream = BytesToMemoryStream(source))
{
pdfStamper = new PdfStamper(pdfReader, stream);
int total = pdfReader.NumberOfPages + 1;
iTextSharp.text.Rectangle psize = pdfReader.GetPageSize(1);
float width = psize.Width;
float height = psize.Height;
PdfContentByte content;
BaseFont font = BaseFont.CreateFont(BaseFont.HELVETICA, BaseFont.WINANSI, BaseFont.NOT_EMBEDDED);
PdfGState gs = new PdfGState();
for (int i = 1; i < total; i++)
{
//content = pdfStamper.GetOverContent(i);//在内容上方加水印
//content = pdfStamper.GetUnderContent(i);//在内容下方加水印
content = OverContent == 1 ? pdfStamper.GetOverContent(i) : pdfStamper.GetUnderContent(i);
//透明度
gs.FillOpacity = markOpacity;
content.SetGState(gs);
for (int j = 1; j <= 4; j++)
{
//开始写入水印文本
content.BeginText();
content.SetColorFill(iTextSharp.text.BaseColor.GRAY);
content.SetFontAndSize(font, 30);
content.SetTextMatrix(0, 0);
content.ShowTextAligned(iTextSharp.text.Element.ALIGN_CENTER, waterMark, width - 120 * j, height - 120 * j, -30);
content.EndText();
}
}
pdfStamper.Close();
rtnContent = stream.ToArray();
}
}
catch (Exception ex)
{
throw ex;
}
finally
{
if (pdfReader != null)
pdfReader.Close();
}
return rtnContent;
}
public static MemoryStream BytesToMemoryStream(byte[] source)
{
var ms = new MemoryStream();
int read;
while ((read = ms.Read(source, 0, source.Length)) > 0)
{
ms.Write(source, 0, read);
}
return ms;
}