Is it possible to associate part of a drawing to a pdfcomment (or similar) interactive bubble?

Question

It is apparently possible to put a TikZ drawing inside a pdfcomment (but using mbox).

Is is possible to associate only part of a drawing (e.g. a line) to a pdfcomment? Below it is the suggested code.

I am open to use other interactive packages (similar to pdfcomment) if that can solve the problem. The final goal is to associate individual curves in a pgfplot to a tooltip when dragging the mouse.

\documentclass[]{article}
\usepackage{tikz}
\usepackage[]{pdfcomment}
\begin{document}

%ok
\pdfmarkupcomment[]{
    text
}{
    a paragraph
}

% ok but needs mbox
\pdfmarkupcomment[]{
    \mbox{
    \begin{tikzpicture}
    \draw(0,0)--(1,1);
    \draw(0,1)--(1,0);
    \end{tikzpicture}}
}{
    a drawing
}

%not ok (Error: Missing } inserted.)
\begin{tikzpicture}
    \pdfmarkupcomment[]{
        \draw(0,0)--(1,1);
    }{
        a line
    }
    \draw(0,1)--(1,0);
\end{tikzpicture}

\end{document}

Answer 1

This question can be solved in several parts:

In what extend can pdf comments be part of TikZ pictures?

As long as the comment is put inside a node{}, there is nothing impossible. In fact, you can put almost everything inside a node{}. For example:

\tikz[remember picture,id=right triangle]{
    \draw(0,0)node[below]{\pdfmarkupcomment[color=yellow]{$A$}{This is (0, 0)}}
       --(6,0)node[right]{\pdfmarkupcomment[color=yellow]{$B$}{This is (6, 0)}}
       --(0,3)node[above]{\pdfmarkupcomment[color=yellow]{$C$}{This is (0, 3)}};
       --cycle
}

How to make a comment associated to a line/polyline/polygon?

The pdfcomment provide \pdflinecomment so that you can, according to the manual, typeset a comment in form of a line, polyline or polygon at the wished spot of the page.

For example:

\pdflinecomment[type=polyline,opacity=1,color=green,line={
    200 500 260 500 200 530
}]{This is a triangle comment!}

How to position this comment

From the previous example we see that a line comment is defined by x- and y- coordinates, in bp, relative to the lower left corner of this page. But how do we generate these numbers automatically so that the comment coincides with the triangle in TikZ pucture?

A possibility is that TikZ has an option called remember picture and it will store the position of the TikZ picture. By using this imformation we have a chance to calculate the coordinates we need.

But instead of doing boring maths, we can fire \pgfsys@markposition multiple times so that every position we need are stored. And again, there is nothing impossible if you put them in node{}'s:

\def\markposition#1{
    \pgfsys@markposition{#1}
}
\tikz{
    \draw(0,0)node{\markposition{point A}}
       --(6,0)node{\markposition{point B}}
       --(0,3)node{\markposition{point C}}
       --cycle;
}

And then we can retrieve those coordinate by \pgfsys@getposition:

\def\getposition#1#2#3{
    \pgfsys@getposition{#1}\pointposition\pointposition
    \pgf@sys@bp@correct\pgf@x\xdef#2{\pgf@sys@tonumber\pgf@x}
    \pgf@sys@bp@correct\pgf@y\xdef#3{\pgf@sys@tonumber\pgf@y}
}
\getposition{point A}\Ax\Ay
\getposition{point B}\Bx\By
\getposition{point C}\Cx\Cy

Now \Ax is the x-coordinate of A, and so on. So afterwards we can these coordinates in \pdflinecomment as follows:

\let~\space
\pdflinecomment[type=polyline,opacity=1,color=blue,line={
    \Ax~\Ay~\Bx~\By~\Cx~\Cy
}]{This is a triangle comment!}

Can I get rid of the ugly blue drawing?

Change the opacity:

Full code

\documentclass{article}
\usepackage{tikz,pdfcomment,lipsum}
\begin{document}

\lipsum[1]

\tikz[remember picture,id=right triangle]{
    \draw(0,0)node[below]{\pdfmarkupcomment[color=yellow]{$A$}{This is (0, 0)}}
       --(6,0)node[right]{\pdfmarkupcomment[color=yellow]{$B$}{This is (6, 0)}}
       --(0,3)node[above]{\pdfmarkupcomment[color=yellow]{$C$}{This is (0, 3)}}
       --cycle;
}

\lipsum[2]

\clearpage

\lipsum[3]

\pdflinecomment[type=polyline,opacity=1,color=green,line={
    200 500 260 500 200 530
}]{This is a triangle comment!}

\lipsum[4]

\clearpage

\lipsum[5]

\makeatletter

\def\markposition#1{
    \pgfsys@markposition{#1}
}
\tikz{
    \draw(0,0)node{\markposition{point A}}
       --(6,0)node{\markposition{point B}}
       --(0,3)node{\markposition{point C}}
       --cycle;
}
\def\getposition#1#2#3{
    \pgfsys@getposition{#1}\pointposition\pointposition
    \pgf@sys@bp@correct\pgf@x\xdef#2{\pgf@sys@tonumber\pgf@x}
    \pgf@sys@bp@correct\pgf@y\xdef#3{\pgf@sys@tonumber\pgf@y}
}
\getposition{point A}\Ax\Ay
\getposition{point B}\Bx\By
\getposition{point C}\Cx\Cy
\let~\space
\pdflinecomment[type=polyline,opacity=.5,color=blue,line={
    \Ax~\Ay~\Bx~\By~\Cx~\Cy
}]{This is a triangle comment!}

\lipsum[6]

\end{document}