使用iTextsharp错误将行添加到pdf无法看到行

Question

I have a PDF File and I am trying to put a line in it using iTextSharp like this.

string Oldfile = @"C:\ThisTest.pdf";
    string NewFile = @"C:\NewOne.pdf";
    PdfReader reader = new PdfReader(Oldfile);
    iTextSharp.text.Rectangle Size = reader.GetPageSizeWithRotation(1);
    Document document = new Document(Size);
    FileStream fs = new FileStream(NewFile, FileMode.Create, FileAccess.Write);
    PdfWriter weiter = PdfWriter.GetInstance(document, fs);
    document.Open();
    PdfContentByte cb = weiter.DirectContent;
    BaseFont bf = BaseFont.CreateFont(BaseFont.HELVETICA, BaseFont.CP1252, BaseFont.EMBEDDED);
    cb.SetColorFill(BaseColor.DARK_GRAY);
    cb.SetFontAndSize(bf, 8);
    cb.BeginText();
    string text = "Haseeb Ahmad";
    cb.ShowTextAligned(1, text, 520, 640, 0);
    cb.EndText();
    PdfImportedPage page = weiter.GetImportedPage(reader, 1);
    cb.AddTemplate(page, 0, 0);
    document.Close();
    fs.Close();
    weiter.Close();
    reader.Close();

I am trying to add a line to the end of this Document but after it does that code it creates the file and when I open it i cant see that text. When i do a search for that word it says its's there. Like this

That mean the code worked all the problem is the font can any one tell me how to make it come to the end of the page and show up instead of being hidden ?

Answer 1

Your code first draws the text

cb.SetColorFill(BaseColor.DARK_GRAY);
cb.SetFontAndSize(bf, 8);
cb.BeginText();
string text = "Haseeb Ahmad";
cb.ShowTextAligned(1, text, 520, 640, 0);
cb.EndText();

and thereafter copies the original page into this

PdfImportedPage page = weiter.GetImportedPage(reader, 1);
cb.AddTemplate(page, 0, 0);

Thus, your original page contents (which may include a white background fill) cover your new text.

Please change the order, copy the page first and then write the text.

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If your task is indeed putting some text onto existing pages of an existing PDF , you should use other iText classes entirely: PdfStamper is made for just this kind of task while the PdfWriter is more made for creating new PDFs from scratch.

Your approach is quite lossy (it drops document level information and interactive parts like form fields) while PdfStamper keeps as much of the original PDF as possible.