Saving Canvas as TeX

Being able to generate TeX graphics can be useful for several reasons:

• To have an easy to modify the image, in particular the labels and titles (ASCII file).
• To have the same font in all labels, legends, plot titles etc. as in the text body of a document.
• Render Math formulae using TeX.

The TeX text engine is powerful and can render any complex math formulae. But more tricky is the graphics rendering: lines, polygons, markers etc … One possibility is to render them using PDF or PostScript and render the text using TeX. But that’s not very practical as two files are needed to render one picture. A better way is to use a dedicated environment like PGF/TikZ.

“ PGF (A Portable Graphic Format for TeX) is a macro package for creating graphics. It is platform- and format-independent and works together with the most important TeX backend drivers, including pdftex and dvips. It comes with a user-friendly syntax layer called TikZ. “

The new class TTeXDump allows to generate PGF/TikZ files. To generate a such file in ROOT it is enough to do:

   gStyle->SetPaperSize(10.,10.);
   hpx->Draw();
   gPad->Print("hpx.tex");

Then, the generated file (hpx.tex) can be included in a LaTeX document (simple.tex) in the following way:

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{patterns}
\usetikzlibrary{plotmarks}
\title{A simple LaTeX example}
\date{July 2013}
\author{O.Couet}
\begin{document}
\maketitle
The following image as been generated using the TTeXDump class.
To include it in a LaTeX document it is enough to specify the following
three directives at the top of the LaTex document:
\begin{verbatim}
\usepackage{tikz}
\usetikzlibrary{patterns}
\usetikzlibrary{plotmarks}
\end{verbatim}
Then to include the picture ({\tt hpx.tex} in this case) in a LateX
 document it is done the usual way:
\begin{verbatim}
\scalebox{0.3}{\input{hpx.tex}}
\end{verbatim}
\par
\begin{figure}[htbp]
\begin{center}
\scalebox{0.5}{\input{hpx.tex}}
\caption{Image ({\tt hpx.tex}) generated thanks to {\tt TTeXDump}}
\end{center}
\end{figure}
\end{document}