TeX, free floating, anchors

Question

I want to achieve the following:

1. I want a single page to consist of N "regions."

   Each region has a x-start, y-start, and a \hbox (denoting the contents of the region).

2. Furthermore, for each region, I want to be able to define "anchors" within the reason.

3. I want to be able to draw arrows pointing from one anchor to another anchor.

What is the best way to achieve this in TeX?

Answer 1

Here is one way to do it with, what else, but tikz:

The content is placed with

\AnchoredRegion[<draw options>]{<name of region>}{x,y}{<content>}

where:

• <draw options> is an optional parameter used to style the box. If you don't want the box, you can use fill=none. If you want a solid box use draw=<color>, etc...
• <name of region> is the name given to this node which can later be used to reference it's location
• x,y is the x and y offset form the south west corner of the page. The units for this default to cm, but if you prefer other unit you can provide them. For example {1in,1in} would be equivalent to {2.54cm,2.54cm} or {2.54,2.54}.
• <content> is the content that is to be placed

After the boxes are placed then you can draw line from one to the other as desired with:

\DrawLines[<draw options>]{<name of region>}{<name of region>}

Only a very small subset of the options that are avilable are illustrated here. For other draw options one should refer to the tikz/pgf user manual.

Note:

• This does require two runs. First one to determine the locations, and the second to do the drawing.
• Note that no test is made to ensure you are no overlapping boxes. So, if that is not desired, you may need to tweak the x, y coordinates of the locations of these tikz nodes.

---

Code:

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{calc}

\newcommand{\AnchoredRegion}[4][]{%
    % #1= draw options
    % #2= name of this node
    % #3= x,y offset from south west of current page
    % #4= content for node
    \begin{tikzpicture}[overlay,remember picture, outer sep=0, inner sep=5pt]
        \node [#1] (#2) at
            ($(current page.south west)+(#3)$)
            {#4};
    \end{tikzpicture}%
}

\newcommand{\DrawLines}[3][]{%
    \begin{tikzpicture}[overlay,remember picture, outer sep=0, inner sep=5pt]
        \draw [ultra thick, #1] (#2) to (#3);
    \end{tikzpicture}%
}%

\newcommand*{\TextA}{\parbox{3.0cm}{\raggedright Some small text over two lines.}}%
\newcommand*{\TextB}{\parbox{3.0cm}{\raggedright Some longer piece of text that takes up three lines.}}%
\newcommand*{\TextC}{\parbox{3.0cm}{\raggedright Some even longer piece of text thatjust goes on and on and on and on..... Well you get the idea.}}%

\begin{document}
    \AnchoredRegion[fill=yellow!40]{YellowRegion}{7,7}{\TextA}
    \AnchoredRegion[fill=cyan!40]{BlueRegion}{7,10}{\TextB}
    \AnchoredRegion[fill=orange!40]{OrangeRegion}{7,13}{\TextC}
    \AnchoredRegion[fill=red!20]{RedRegion}{11,13}{\TextC}

    \DrawLines[out=130,in=-130,-stealth, red]
            {YellowRegion.west}{OrangeRegion.west}
    \DrawLines[out=30,in=-90,-stealth, brown, dotted]
            {YellowRegion.east}{RedRegion.south}
    \DrawLines[-stealth, violet]{BlueRegion.south}
            {YellowRegion.north}
    \DrawLines[out=-150,in=120, distance=6cm, -stealth, green]
            {YellowRegion.south}{OrangeRegion.north}
\end{document}