分享程序员开发的那些事...
更新时间：2021-12-03 02:48:47
1、用iTextSharp去除文字水印。（水印文字需在contents中）
————Removing Watermark from a PDF using iTextSharp
2、用iTextSharp去除图片水印。（水印图片需为xobject对象）
————Remove mask image“Watermark” from PDF itextsharp
3、使用PDFlib-6.0.2库生成PDF文档的水印清除方法
example code：
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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using iTextSharp.text;
using iTextSharp.text.pdf;
namespace ClearWatermark
{ class Program
{
static void Main(string[] args)
{
string pathfile_in = "D:\\test\\input\\test.pdf";
string pathfile_out = "D:\\test\\output\\test.pdf";
ProcOne4Contents(pathfile_in, pathfile_out);
ProcOne4Xobject(pathfile_in, pathfile_out);
Console.ReadKey();
}
//去文字水印示例（walker）
static bool ProcOne4Contents(string pathfile_in, string pathfile_out)
{
PdfReader pdfReader = new PdfReader(pathfile_in);
PRStream stream;
String content;
PdfDictionary page;
PdfArray contentarray;
int pageCount = pdfReader.NumberOfPages;
for (int i = 1; i <= pageCount; ++i)
{
page = pdfReader.GetPageN(i);
contentarray = page.GetAsArray(PdfName.CONTENTS);
if (contentarray != null)
{
for (int j = 0; j < contentarray.Size; j++)
{
stream = (PRStream)contentarray.GetAsStream(j);
content = System.Text.Encoding.ASCII.GetString(PdfReader.GetStreamBytes(stream));
//if (content.IndexOf("/OC") >= 0 && content.IndexOf("I'm watermark") >= 0)
if (content.Length == 123 && content.IndexOf("I'm watermark") >= 0)
{
stream.Put(PdfName.LENGTH, new PdfNumber(0));
stream.SetData(new byte[0]);
}
}
}
}
pdfReader.RemoveUnusedObjects();
//写到输出文件
using (FileStream outStream = new FileStream(pathfile_out, FileMode.Create, FileAccess.Write, FileShare.None))
{
using (PdfStamper stamper = new PdfStamper(pdfReader, outStream))
{
}
}
return true;
}
//去图片水印示例（walker）
static bool ProcOne4XObject(string pathfile_in, string pathfile_out)
{
string pdfTempFilename = pathfile_out;
FileStream outStream = new FileStream(pdfTempFilename, FileMode.Create);
PdfReader pdfReader = new PdfReader(pathfile_in);
PdfStamper stp = new PdfStamper(pdfReader, outStream); //关联输入和输出
PdfDictionary page1 = pdfReader.GetPageN(1);
PdfDictionary res = (PdfDictionary)PdfReader.GetPdfObject(page1.Get(PdfName.RESOURCES));
PdfDictionary xobjDict = (PdfDictionary)PdfReader.GetPdfObject(res.Get(PdfName.XOBJECT));
if (xobjDict != null)
{
foreach (PdfName name in xobjDict.Keys)
{
//Console.WriteLine("name:" + name.ToString());
PdfObject obj = xobjDict.Get(name);
if (obj.IsIndirect())
{
PdfDictionary objDict = (PdfDictionary)PdfReader.GetPdfObject(obj);
PdfName type = objDict.GetAsName(PdfName.SUBTYPE);
//Console.WriteLine("type:" + type);
if (PdfName.IMAGE.Equals(type) && name.ToString().IndexOf("I1") > 0)
{
PdfReader.KillIndirect(obj);
}
}
}
}
pdfReader.RemoveUnusedObjects();
stp.Close();
return true;
}
/*通过提取内容创建新PDF来变相去水印（walker）
* 参考：http://www.sharejs.com/codes/csharp/8619
* http://www.4guysfromrolla.com/articles/030911-1.aspx
* https://gist.github.com/7shi/805326
*/
static void ProcOneByExtract(string pathfile_in, string pathfile_out)
{
PdfReader pdfReader = new PdfReader(pathfile_in);
Document outDocument = new Document();
FileStream outStream = new FileStream(pathfile_out, FileMode.Create);
PdfWriter pdfWriter = PdfWriter.GetInstance(outDocument, outStream);
outDocument.Open();
int pageNum = pdfReader.NumberOfPages;
Console.WriteLine("pageNum:" + pageNum);
for (int i = 1; i <= pageNum; i++)
{
PdfDictionary pg = pdfReader.GetPageN(i);
PdfDictionary res = PdfReader.GetPdfObject(pg.Get(PdfName.RESOURCES)) as PdfDictionary;
PdfDictionary xobj = PdfReader.GetPdfObject(res.Get(PdfName.XOBJECT)) as PdfDictionary;
if (xobj == null)
{
Console.WriteLine("xobj == null");
continue;
}
var keys = xobj.Keys;
if (keys.Count == 0)
{
Console.WriteLine("keys.Count == 0");
continue;
}
PdfObject obj = xobj.Get(keys.ElementAt(0));
if (!obj.IsIndirect())
{
Console.WriteLine("!obj.IsIndirect()");
continue;
}
PdfDictionary tg = PdfReader.GetPdfObject(obj) as PdfDictionary;
PdfName type = PdfReader.GetPdfObject(tg.Get(PdfName.SUBTYPE)) as PdfName;
Console.WriteLine("type:" + type);
if (!PdfName.IMAGE.Equals(type))
{
continue;
}
int XrefIndex = (obj as PRIndirectReference).Number;
PRStream pdfStream = pdfReader.GetPdfObject(XrefIndex) as PRStream;
byte[] data = PdfReader.GetStreamBytesRaw(pdfStream);
Image img = Image.GetInstance(obj as PRIndirectReference);
float pageWidth = pdfReader.GetPageSize(i).Width;
float pageHeight = pdfReader.GetPageSize(i).Height;
float imgWidth = img.Width;
float imgHeight = img.Height;
outDocument.SetPageSize(new Rectangle(pageWidth, pageHeight));
outDocument.NewPage();
img.ScaleToFit(pageWidth, pageHeight);
img.SetAbsolutePosition(0, 0);
outDocument.Add(img);
}
outDocument.Close();
}
}
} |
*** walker ***