How to change the page height on current page so as to include each section in one page?

Question

I consider posting some materials as .jpg file on my blog which produced from a .tex document.

This document includes lots of sections which is about 1500-2300 words. I need neither header nor page number. I can also accept the endnotes.

I want each .jpg file corresponded with just a whole section, as shown by follow images. (The images were transformed from a .pdf file.)

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page i (also section 1)

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page ii (also section 2)

---

page iii (also section 3)

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But, I failed on trying to change the page's height on each page. It is seem that the entire document could set only a fixed page size. I think maybe the requirement can be implemented by

1. On the beginning of every section, put a \newpage command.

2. Set a sufficient page height value (as we known, the page size of a .tex file can be several meter long).

3. Typeset the file, record (using some technique) the total length of vbox at the end of current page.

4. Use the record value to set a new page height.

5. typeset again, but just typeset the section I needed.

Does above said describe a right way? Could someone tell me how to implement it automatically?

Or is there a more convenient way to achieve the result?

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EDIT:

Hi Chris H, the preview package suppressed the setting of\lineskiplimit or/and \lineskip. Try the code below

documentclass{book}

\usepackage[

active, %if annotate the line obtain fig 1

tightpage]{preview}\setlength{\PreviewBorder}{9pt}

\begin{document}

\setlength{\lineskiplimit}{9pt}\setlength{\lineskip}{9pt}

\begin{preview}

\begin{flushleft}

\fbox{It attempt to compare nil with number}

\fbox{It attempt to compare nil with number}

\end{flushleft}

\end{preview}

\end{document}

obtain fig 2.

fig 1

fig 2

So, the substances in each section would be inappropriate.

Answer 1

If you don't need a footer and are ok with footnotes relegated to the end of the document via endnotes then a simple modification of your proposed workflow could fit the bill.

1. \usepackage [paperheight=50cm, textheight=48cm, paperwidth=21cm]{geometry} or whatever is enough instead of 50cm, 48cm. Or only paperheight and vscale=0.95 for example. The 21cm if for A4 paper width. Adjust as desired.
2. \pagestyle{empty} in the preamble and \thispagestyle{empty} on the first page (if using article class).
3. End each section with a \clearpage. Do not make footnotes, or use rather endnotes package.
4. Either:
   • use latex myfile.tex + dvipng -Ttight myfile.dvi to generate one png per page, with tight bounding box. Use for example -D200 to get twice as many pixels (per dimension, so 2x2=4 as many pixels, really) than the default (which I believe is 100 pixels per inch of the original; but dvipng does not store the real pixel dimensions in the produced file [last time I checked about a year ago] and browsers display with pixels on the final device so the higher resolution the final device, the smaller the image appears [last time I checked about a year ago])
   • or use pdflatex myfile.tex (or anything with pdf output) then pdfcrop myfile.pdf to get myfile-crop.pdf then something such as gs -dSAFER -dBATCH -dNOPAUSE -sDEVICE=png16m -r300 -dDownScaleFactor=3 -o myfile%02d.png myfile-crop.pdf to generate png files with colors. Use pnggray (but not pngmono) if you don't need colors. Use gs -dSAFER -dBATCH -dNOPAUSE -sDEVICE=jpeg -o myfile%02d.png myfile-crop.pdf for generating jpeg pictures instead. Additional relevant switches for jpeg are -r for the resolution in dots per inch (default 72) and -dJPEGQ=N (integer from 0 to 100, default 75) for the quality. I never use jpeg so I can't say more on it!

All of the above is a bit theoretical, if it doesn't work, do complain!

Answer 2

My previous comment considered using the standalone documentclass. That uses the preview package. Going directly to preview gives a solution:

\documentclass{article}
\usepackage{lipsum}
\usepackage[active, tightpage]{preview}

\begin{document}
\begin{preview}
\section{Intro}
\lipsum[1]
\end{preview}
\newpage
\begin{preview}
\section{Another section}
\lipsum[2]
\end{preview}
\end{document}

The tightpage option does the cropping for you as well.

EDIT:Here's where I derived this answer from:https://tex.stackexchange.com/a/51627/28808