Large TikZ pictures scaled to a page - part 2

Question

I need to draw the plans of a house and make them fit on a page. I would really like to have one set of dimensions/coordinates both in the real life and in my TeX file (I tried in the past to have some dirty scalings, i.e. one dimension in the TeX file others in the real life, but that's not ok).

Is there a way to overcome this error? Thank you! (Please remark the 50m by 50m both in drawing and in the grid)

[Loading MPS to PDF converter (version 2006.09.02).]
)
! Dimension too large.
<to be read again> 
                   \relax 
l.28   \end{scaletikzpicturetowidth}

A MWE (Miktex 2.9.4248 x64; pdfTeX, Version 3.1415926-2.5-1.40.14):

\documentclass[fleqn]{article}
\usepackage{tikz}
\usepackage{pdflscape}
\usepackage{environ}%%%%%%%%%%%%%%%%%%%%%%%%%%
\makeatletter%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\newsavebox{\measure@tikzpicture}%%%%%%%%%%%%%
\NewEnviron{scaletikzpicturetowidth}[1]{%
  \def\tikz@width{#1}%
  \def\tikzscale{1}\begin{lrbox}{\measure@tikzpicture}%
  \BODY
  \end{lrbox}%
  \pgfmathparse{#1/\wd\measure@tikzpicture}%
  \edef\tikzscale{\pgfmathresult}%
  \BODY
}
\makeatother
\begin{document}
\begin{center}
  \begin{scaletikzpicturetowidth}{\textwidth}
    \begin{tikzpicture}[scale=\tikzscale]
      \draw [step=10cm, lightgray, very thin] (0,0) grid  (50000mm,50000mm);
      \draw [draw=black, thin] (0.0mm, 0.0mm) rectangle ++(50000mm,50000mm) node[pos=.5] {some labels};
    \end{tikzpicture}
  \end{scaletikzpicturetowidth}
\end{center}
\end{document}

Answer 1

• Use dimensionless coordinates.
• Specify the unit length by adding e.g. the option [x=0.005pt,y=0.005pt] to your tikzpicture.

\documentclass{article}
\usepackage{tikz}
\usepackage{lipsum}
\begin{document}
\lipsum[1]
\begin{center}
  \begin{tikzpicture}[x=0.005pt,y=0.005pt]
    \draw [step=100, lightgray, very thin] (0,0) grid  (50000,50000);
    \draw [draw=black, thin] (0.0, 0.0) rectangle ++(50000,50000) node[pos=.5] {some labels};
  \end{tikzpicture}
\end{center}
\lipsum[2]
\end{document}

Auto-scaling the picture to a given width: The environment scaletikzpicturetowidth of the original posting (based on an answer by Philippe Goudet, which in turn is based on a solution by Ulrike Fischer on comp.text.tex) can be adapted to this approach. Add the following lines to the preamble:

\usepackage{environ}
\newsavebox{\measuretikzpicture}
\NewEnviron{scaletikzpicturetowidth}[1]{%
  \def\tikzscale{0.05}% choose small enough to avoid overflows, but large enough to minimize rounding errors
  \savebox{\measuretikzpicture}{\BODY}%
  \pgfmathparse{#1/\wd\measuretikzpicture*\tikzscale}%
  \edef\tikzscale{\pgfmathresult}%
  \BODY
}

In theory, the magic number 0.05 in this definition could be any number, e.g. 1 as in the original posting. In practice, however, numbers in TeX are limited to a small range, so \tikzscale has to be small enough such that no overflows occur (like described in the original posting), but also large enough such that the rounding errors remain negligible. You will notice overflows by TeX giving an error message, while bad rounding errors will result in inadequate scaling.

\documentclass{article}
\usepackage{tikz}
\usepackage{environ}
\newsavebox{\measuretikzpicture}
\NewEnviron{scaletikzpicturetowidth}[1]{%
  \def\tikzscale{0.05}% choose small enough to avoid overflows, but large enough to minimize rounding errors
  \savebox{\measuretikzpicture}{\BODY}%
  \pgfmathparse{#1/\wd\measuretikzpicture*\tikzscale}%
  \edef\tikzscale{\pgfmathresult}%
  \BODY
}
\usepackage{lipsum}
\begin{document}
\lipsum[1]
\begin{center}
  \begin{scaletikzpicturetowidth}{\textwidth}%
    \begin{tikzpicture}[x=\tikzscale pt,y=\tikzscale pt]
      \draw [step=100, lightgray, very thin] (0,0) grid  (50000,20000);
      \draw [draw=black, thin] (0.0, 0.0) rectangle ++(50000,20000) node[pos=.5] {some labels};
    \end{tikzpicture}%
  \end{scaletikzpicturetowidth}
\end{center}
Same picture, but smaller by a factor of 10 (50000 replaced by 5000), again scaled to the text width.
\begin{center}
  \begin{scaletikzpicturetowidth}{\textwidth}%
    \begin{tikzpicture}[x=\tikzscale pt,y=\tikzscale pt]
      \draw [step=100, lightgray, very thin] (0,0) grid  (5000,2000);
      \draw [draw=black,thin] (0.0, 0.0) rectangle ++(5000,2000) node[pos=.5] {some labels};
    \end{tikzpicture}%
  \end{scaletikzpicturetowidth}
\end{center}
\lipsum[2]
\end{document}