How define a fixed width page, but length > some minimum length, but only as long as needed

Question

This recent question on how to increase the width of the output, and this earlier question on how to increase the length of the output reminded me of something I have been wondering: I would like to fix the width and have the length to be longer than some minimum length, but only as long as necessary.

So far I have been using the geometry package to fix the width, and set the page length to be very long as per the above links, and this has been working. However, I would like to not have the extra blank space at the bottom for very short pages.

This is intended to generate individual pages for on screen viewing, and not a long document. Hence the desire for a single "page".

Answer 1

\documentclass{article}
\usepackage{geometry}
\geometry{paperwidth=12cm,paperheight=\maxdimen,margin=1cm}

\usepackage{lipsum}

\begin{document}
\setbox0=\vbox{
\lipsum
}
\dimen0=\dp0
\pdfpageheight=\dimexpr\ht0+2cm\relax
\ifdim\pdfpageheight<12cm \pdfpageheight=12cm \fi
\unvbox0\kern-\dimen0

\end{document}

If you try \lipsum[1] instead of \lipsum you get 12cm as height. This can be made automatic, I believe, by hooking into \begin{document} and \end{document}.