Append a dynamically changing watermark to a PDF in SharePoint

Question

This is primarily a question of possibilities more than instructions. I'm a programming consultant working on a WSS project site system for my client. We have a document library in which files are uploaded to go through a complex approval process. With multiple stages in this process, we have an extra field which dictates what the current status of the document is.

Now, my client has become enamored with the idea of PDF watermarking. He wants the document (which is already a PDF) to be affixed with a watermark corresponding to the current status, such that with each stage of the approval process the watermark will change.

One method, the traditional method for PDF watermarking, of accomplishing this is to have one "clean" copy of the document somewhere hidden on the site, and create a new PDF from it that has the watermark at each stage of the approval process. Since the filename will never change, this new PDF can be uploaded continually to a public library, always overwriting the old version and simulating a "dynamically changing watermark". However, in the various stages there will also be people uploading clean copies with corrections and suggestions, nevermind the complex nature of juggling around two libraries and the fact we double the number of files stored. My client and I agree that this is not a practical path to choose.

What we would like to do is be able to "modify" the watermark in a PDF, so that we only have to keep one copy of the file. Unfortunately, from what I've seen, in most cases when you make something like a watermark, which in its nature is supposed to be "unmodifyable", you won't be able to edit it later. So, is it possible to have a part of a PDF which cannot be changed by anyone who downloads the file, but can be changed as part of a workflow or other object model process? Thanks in advance!

Answer 1

It sounds to me like you want to allow people to modify the PDF they download, but not modify its watermark. This is probably going to be nigh on impossible if the watermark is embedded in the PDF (afaict) but what if the watermark image is external to the PDF; is it possible to embed a watermark in a PDF that is sourced via HTTP? Then you could embed:

<watermark image="http://sharepoint/site/_vti_bin/docstatus.asmx?id=5"&gt;

Of course, I have no idea about PDFs, so this might not be possible but you get the concept.

-Oisin

Answer 2

You could use Event Handlers such that code was run every time a document was checked in. In that code you could perform the fixup/check that made the watermark be what you wanted it to be. This assumes you can write code that manipulates a PDF's internal structure such that it has the watermark that you desire.

Answer 3

PDF Watermarking in SharePoint is a common request. I have written extensively on this topic. See:

1. Adding a dynamic watermark to a PDF file from a SharePoint Workflow
2. Adding a (static) watermark to a PDF file from a SharePoint Workflow
3. Use SharePoint Workflows to inject JavaScript into PDFs and print the ‘open date’