color and pagesize

[GHT54]

The two following files produce different output

File 1
\input eplain
\hsize=210mm
\input miniltx
\input color
\the\pdfpageheight
\end

File 2
\input eplain
\hsize=210mm
\input miniltx
%\input color
\the\pdfpageheight
\end

test2.log

[muzimuzhi]

• TeX Live is installed with A4 paper chosen by default
  See answer by Enrico Gregorio (egreg) on TeX.SX and stdout of tlmgr paper.
  • For pdftex, \pdfpageheight is initialized to 297 true mm (in pdftexconfig.tex), the height of A4 paper.
• eplain.tex declares \paperheight with initial value (11in) for letter paper.
• Page size of the resulted PDF is controlled by \pdfpageheight.

Then,

• Without \input color, the initial value of \pdfpageheight for A4 paper is effected.
• With \input color, the \pdfpageheight is set equal to the \paperheight in color driver file (pdftex.def for pdftex engine), thus the resulted page size in PDF becomes letter paper.

This difference also happens in LaTeX:

\documentclass{article}
% \usepackage{color} % or any other pacakge which loads color/graphics driver

\begin{document}
content
\end{document}

In the LaTeX example above, the article document class always uses letterpaper class option, but it only actually affect the page size when color driver is loaded.

As letter paper has been the default paper size of LaTeX for decades, it seems to me the result with color driver loaded is the expected one.

[davidcarlisle]

LaTeX by default does not set the pdf page size at all (as the syntax to do that depends on the back end in use, pdftex, or latex/dvips or latex/dvipdfmx etc) once a back end has been chosen (color, or graphics or hyperref or geometry packages for example all force a choice of back end) then the pdf page size (\pdfpageheight for pdftex) is set to the latex parameter \paperheight (and similarly for width)

To you get the equivalent to latex behaviour. You can set \paperheight

\input eplain
\showthe\pdfpageheight
\hsize=210mm
\input miniltx
\paperheight=\pdfpageheight
\input color
\showthe\pdfpageheight
\end

Then you get 845.04684pt whether or not color is loaded.

[muzimuzhi]

your eplain code never sets \paperheight so you get the default latex behaviour.

@davidcarlisle I assume you meant \pdfpageheight here? Because eplain does set \paperheight (to 11in if \mag=1000 or 11truein otherwise).

[davidcarlisle]

@muzimuzhi oops, I meant what I wrote but it wasn't right as you say. Maybe I'll delete the first comment and correct later, thanks