How to place a "floating text box" at a specified location in page coordinates

Question

I have read this thread, but I don't think it addresses the same problem.

I am looking for a way to have a command in LaTeX with an interface as follows:

\placetextbox{x_in_page_percentage, y_in_page_percentage}{This is my text}

The command would place the text This is my text centered within a box that may overlap with anything else on the page, and that would be placed at the coordinates specified by the variables x_in_page_percentage and y_in_page_percentage. These variables control the location of the x in the diagram below. E.g.

-------------x---------------
      This is my text
-----------------------------

This way, something like \placetextbox{0.5, 0.5}{This is my text} would place the text roughly on the center of the page, regardless of anything else that may be on that location.

Any thoughts how to do this?

Answer 1

The eso-pic package allows you to add pictures (and text) to pages as an overlay/in the foreground [as an underlay/in the background]. The specific command used to add content to the current page is \AddToShipoutPictureFG* [\AddToShipoutPictureBG*]. The starred * versions of these commands limit the output to the current page, while the unstarred versions ship its contents out to every page.

The following minimal example illustrates the technique used to answer your question in the form of a macro \placetextbox{<horizontal pos>}{<vertical pos>}{<stuff>}:

\documentclass{article}
\usepackage[english]{babel}
\usepackage{lipsum}% For 'Lorem Ipsum' dummy text
\usepackage[pscoord]{eso-pic}% The zero point of the coordinate systemis the lower left corner of the page (the default).

\newcommand{\placetextbox}[3]{% \placetextbox{<horizontal pos>}{<vertical pos>}{<stuff>}
  \setbox0=\hbox{#3}% Put <stuff> in a box
  \AddToShipoutPictureFG*{% Add <stuff> to current page foreground
    \put(\LenToUnit{#1\paperwidth},\LenToUnit{#2\paperheight}){\vtop{{\null}\makebox[0pt][c]{#3}}}%
  }%
}%

\begin{document}
\lipsum[1-5]%
\placetextbox{0.5}{0.5}{\fbox{\Huge\textsf{This is my text.}}}%
\placetextbox{0.5}{1}{\Huge\texttt{Here is another piece of text.}}%
\placetextbox{0.1}{0.1}{\Large $\mathcal{A}_1$}%
\end{document}

Other packages are also capable of doing this, including background and tikz.

Answer 2

I made some improvements to the \placetextbox macro, written by @Werner, including the alignment improvement from comment 3. The issue with relative positioning to the current page, is that on right alined text, the content may go outside of the page, since the left (or center) of the box is used.

The text alignment must now be specified using the #3 argument. Depending on l or r, the vertical pos is now an offset from the left or right respectively from the page edge and horizontal pos is the offset from the top. A unit should be specified, in this case cm.

\newcommand{\placetextbox}[4]{% \placetextbox{<offset top>}{<offset left/right>}{<align>}{<stuff>}
  \setbox0=\hbox{#4}% Put <stuff> in a box
  \AddToShipoutPictureFG*{% Add <stuff> to current page foreground
    \if#3r
    \put(\LenToUnit{\paperwidth-#1},\LenToUnit{\paperheight-#2}){\vtop{{\null}\makebox[0pt][r]{\begin{tabular}{r}#4\end{tabular}}}}%
    \else
    \put(\LenToUnit{#1},\LenToUnit{\paperheight-#2}){\vtop{{\null}\makebox[0pt][l]{\begin{tabular}{l}#4\end{tabular}}}}%
    \fi
  }%
}%

Example usage:

\documentclass{article}
\usepackage[english]{babel}
\usepackage{lipsum}% For 'Lorem Ipsum' dummy text
\usepackage[pscoord]{eso-pic}% The zero point of the coordinate systemis the lower left corner of the page (the default).

% include macro from codeblock above

\begin{document}
\lipsum[1-5]%
\placetextbox{0.1cm}{2cm}{r}{This text should nicely align the the right side \\ at the top of the page}
\placetextbox{0.1cm}{10cm}{l}{\Huge\texttt{Large Text on the left}}%
\end{document}

Output: