Watermark on a pdf wich is embedded in a browser 2007-11-15 - By Adriano Leite Ribero
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I think I have not explained the problem properly.
The String I have, let?s call it inputString, has the following content:
%PDF-1 (See http://PDF-1.ora-code.com).2
%????
3 0 obj
<<
/Linearized 1
... (etc)
(looks similar to the content you see when opening a PDF with notepad,
ultraedit, notepad++, etc)
If I construct a PdfReader the following way:
PdfReader reader = new PdfReader(inputString.getBytes());
it works fine, it opens it, seems no extra transformation is required.
Then I manipulate the file (add the watermark as I have mentioned
before) and write the resulting PDF to the browser, but it looks
exactly like the original one. But the content of the original and
final PDF documents are a little different (the size of the
manipulated document is bigger).
It seems that the watermark is somehow added, and the document
structure is not damaged (otherwise, it wouldn?t load), but something
is wrong. And it has to be related to the transformation between the
inputString and its corresponding byte array.
I?ve tryed to encode the inputString to a Base64 char array, but it is
not the solution. I think this because an exception is throwed when
trying to construct the PdfReader object with the encoded String,
thing that did't happen if I don?t encode the String:
07/11/15 12:33:53 java.io.IOException: PDF header signature not found.
07/11/15 12:33:53 at com.lowagie.text.pdf.PRTokeniser.checkPdfHeader
07/11/15 12:33:53 at com.lowagie.text.pdf.PdfReader.readPdf
07/11/15 12:33:53 at com.lowagie.text.pdf.PdfReader.<init>
So, the steps should be (and in my code are, in fact):
- transform the inputString in a byte[] to construct the PdfReader
- construct the PdfReader
- add the watermark (works ok starting from a PdfReader)
- read the resulting ByteArrayOutputStream (from the PdfStamper
associated to the PdfReader) and transforming it back to a String
(with toString)
What do I miss?
Excuse me for so many questions, I think it must be a detail (because
I?ve done the same with pdf files).
Adriano.
2007/11/15, Adriano Leite Ribero <adriano.leite.ribero@(protected)>:
> Do you mean I have to encode my string (having the pdf content
> "%PDF-1 (See http://PDF-1.ora-code.com).2......") as a base64 char[] and construct the PdfReader
> object passing that char[] as a parameter? (I have to check it, but I
> think PdfReader(char[]) wasn`t a valid constructor...).
>
> Again, lot of thanks for your time,
> Adriano.
>
> 2007/11/15, Paulo Soares <psoares@(protected)>:
> > The problem is that PDF are binary. If you must pass it as a string encoded
it first as base64 and decode it before delivering it to PdfReader.
> >
> > Paulo
> >
> > > -- --Original Message-- --
> > > From: itext-questions-bounces@(protected)
> > > [mailto:itext-questions-bounces@(protected)] On
> > > Behalf Of Adriano Leite Ribero
> > > Sent: Thursday, November 15, 2007 8:47 AM
> > > To: itext-questions@(protected)
> > > Subject: [iText-questions] Watermark on a pdf wich is
> > > embedded in a browser
> > >
> > > Hi,
> > >
> > > I am trying to add some watermark to a pdf document. I've followed
> > > correctly the example of the file "AddWatermarkPageNumbers.java" from
> > > "http://itextdocs.lowagie.com/tutorial/general/copystamp/index.php",
> > > and it works properly. I have made some changes to fit the method in
> > > that java file to my purpose without problems, and renamed the method
> > > in it as "addWaterMark", so my method preWaterMark1, which calls it,
> > > works fine:
> > >
> > > public static void preWaterMark1(String nameOriginalFile, String
> > > text, String image, String nameOutputFile) {
> > > try {
> > > PdfReader reader = new PdfReader(nameOriginalFile);
> > > PdfStamper stamp = new PdfStamper(reader, new
> > > FileOutputStream(nameOutputFile));
> > > addWaterMark(reader, stamp, text, image);
> > > } catch (Exception e){
> > > System.out.println("MarcaDeAgua.preWaterMark ->
> > > Excepci?n: " + e);
> > > }
> > > }
> > >
> > > private static void addWaterMark(PdfReader reader, PdfStamper stamp,
> > > String text, String image){... /*works ok*/}
> > >
> > >
> > > The problem is that i need to do the same with pdf documents that
> > > are not files, they are just in the browser. I start from a String
> > > having the content of a document of that kind, and, following the same
> > > steps I've written preWaterMark2, which uses the same method to write
> > > the watermark. But what I get is just the pdf without any visible
> > > changes, I can?t see any watermark. But I know the String having the
> > > content of the pdf document has changed.
> > >
> > > public static String preWaterMark2(String pdfContent, String text,
> > > String image){
> > > ByteArrayOutputStream baos = new ByteArrayOutputStream();
> > > try {
> > > PdfReader reader = new
> > > PdfReader(pdfContent.getBytes("ISO-8859 (See http://ISO-8859.ora-code.com)-1"));
> > > PdfStamper stamp = new PdfStamper(reader, baos);
> > > addWaterMark(reader, stamp, text, image);
> > > } catch (Exception de){
> > > de.printStackTrace();
> > > }
> > > String ret = "";
> > > try{
> > > if (baos.toString()!= null)
> > > ret = baos.toString();
> > > } catch (Exception e){
> > > System.out.println("MarcaDeAgua.preWaterMark -> Excepci?n: " +
> > > e.getMessage());
> > > e.printStackTrace();
> > > }
> > > return ret;
> > > }
> > >
> > > I guess the problem could be related to the transforming process
> > > between the String having the PDF content and the byte[] with the same
> > > data. I have tryed to change the "ISO-8859 (See http://ISO-8859.ora-code.com)-1", but it keeps on showing
> > > me a PDF without any watermark.
> > >
> > > Does anybody know what could be the problem?
> > >
> > > Lot?s of thanks,
> > > Adriano.
> >
> >
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