Is there are way to annotate pdfs with LaTeX?

Question

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How to annotate PDF files generated by pdflatex?

Is there a way to annotate pdfs with LaTeX annotations? I mean a pdf that I do not have the source code for (or may not have even been written in LaTeX itself, for that matter).

The motivation behind my question is that I would really like to annotate my lecture notes digitally to stop me losing important notes, but the lecturer does not like the idea of releasing the source code to his notes to students. (i.e. I don't think asking for the source code went down well and I would like to not feel the need to ask another lecturer the same question if I can avoid it :-))

I could try to type them out myself but when time is limited it would be ambitious at best, to try it when there are more urgent work I need to prioritise.

I use linux, my pdf viewer is okular and it mainly for maths/physics type work if that is useful information to add. It would be handy to be able to do it one way or another so I am open to any suggestions that might help out!

Answer 1

Here's an example using pdfpages to load the PDF as a background with TikZ to draw on top of it. The following code will complain about a missing image (tikzmark_example.pdf) but hopefully will give you the idea of what I was saying in the comments. I've left the grid in place as that's how I figure out the coordinates. This is adapted from code I use to "fill in" PDF forms by writing on top of them - in other situations I'd probably end up with a different set of helper macros to make it easier to place the annotations.

\documentclass{article}
%\url{http://tex.stackexchange.com/q/85651/86}
\usepackage[svgnames]{xcolor}
\usepackage{pdfpages}
\usepackage{tikz}

\tikzset{
  every node/.style={
    anchor=mid west,
  }
}

\makeatletter
\pgfkeys{/form field/.code 2 args={\expandafter\global\expandafter\def\csname field@#1\expandafter\endcsname\expandafter{#2}}}

\newcommand{\place}[3][]{\node[#1] at (#2) {\csname field@#3\endcsname};}
\makeatother

\newcommand{\xmark}[1]{\node at (#1) {X};}



\begin{document}

\foreach \mykey/\myvalue in {
  ctsfn/{Defined in Week 1},
  metsp/{Defined in Week 3},
} {
  \pgfkeys{/form field={\mykey}{\myvalue}}
}

\includepdf[
  pages=1,
  picturecommand={%
    \begin{tikzpicture}[remember picture,overlay]
%%% The next lines draw a useful grid - get rid of them (comment them out) on the final version
    \draw[gray] (current page.south west) grid (current page.north east);
\foreach \k in {1,...,28} {
      \path (current page.south east) ++(-2,\k) node {\k};
}
\foreach \k in {1,...,20} {
      \path (current page.south west) ++(\k,2) node {\k};
}
%%% grid code ends here
\tikzset{every node/.append style={fill=Honeydew,font=\large}}
\place[name=ctsfn]{14cm,17cm}{ctsfn}
\place[name=metsp]{11cm,9cm}{metsp}
\draw[ultra thick,blue,->] (ctsfn) to[out=135,in=90] (9cm,17.3cm);
\draw[ultra thick,blue,->] (metsp) to[out=155,in=70] (6cm,9cm);
    \end{tikzpicture}
  }
]{tikzmark_example.pdf}

\end{document}

The result of the above is:

Answer 2

Although there might be a way to comment third party PDFs by using LaTeX, this is not a usefull way.

EDIT:

My answer from 2012 (below) is outdated. Under Linux there are many tools to comment or even change PDFs. Okular can annotate PDFs nicely, e.g. »Master PDF Editor« is a commercial tool.

Under Windows there is PDF XChange Editor (not tested) for free, I'm using a commercial tool called PDF Annotator.

But there are many more, depending on your needs.

To annotate a PDF, I often »print« it virtually on a large landscape page. If the to-be-annotated page is DIN A4, I put the page on a DIN A3 landscape and have much space to comment.

\documentclass[DIV=30, paper=A3, paper=landscape]{scrartcl}
\usepackage{pdfpages}
\begin{document}
\includepdf[pages=-, offset= -300 0]{Origin.pdf}
\end{document}

(OLD ANSWER FROM 2012: There are lots of software to deal with your needs, but more on the windows side. Under Linux, I employ flpsed, http://flpsed.org/flpsed.html.)