I am working on a software (http://docear.org) which, amongst other things, tries to extract and keep track of bookmarks and annotations from pdfs to inform the user about changes which he has made to these items.
I am currently facing a larger issue and wonder if you can help me with the following:
I thought the object number and generation was sufficient to identify annotations in a PDF over different versions, because the pdf 1.7 specification (http://www.adobe.com/content/dam/Adobe/ ... ce_1-7.pdf) states on page 63:
But:"Together, the combination of an object number and a generation number
uniquely identifies an indirect object. The object retains the same object number
and generation number throughout its existence, even if its value is modified."
- When I open a pdf file with the PDF-Xchange Viewer which contains annotations created by another pdf reader (e.g. the foxit reader), all the object numbers of the annotations seem to be set to different values after saving it.
- However if I use pdf files which only contain annotations created with the PDF-Xchange Viewser, then the object numbers remain the same.
- If I go the other way around and use a pdf with annotations created by your software and try to open, change and store it with the Foxit PDF Reader, then the object numbers remain the same as well.
I would greatly appreciate any advice or help you can provide.
P.S.: I was using Windows 7 Professional 64-Bit and Version 2.5.200 of the PDF-XChange Viewer.