How to read %%Pages:... from *.xbb file

Question

Given the auxiliary file test.xbb

%%Title: test.pdf
%%Creator: extractbb 20180506
%%BoundingBox: 0 0 300 343
%%HiResBoundingBox: 0.000000 0.000000 300.290000 342.810000
%%PDFVersion: 1.4
%%Pages: 17
%%CreationDate: Mon Jan  7 18:06:49 2019

produced from input file test.pdf using the extractbb utility

extractbb test.pdf

Is there an easy way to read the value of the %%Pages: key from test.xbb by means of some internal command defined in the graphics package? I know that graphics parses user provided xbb files in order to determine bounding-box coordinates for binary-type or compressed image files that TeX cannot read on its own. Can it do the same for %%Pages: out of the box?

Yes, but without using pdftex, luatex, xetex, just by reading xbb while running (pdf|lua)latex in DVI mode. — AlexG, Jan 07 '19 at 19:50
I see nothing in the code. It wouldn't imho be very difficult to add it, but can't you read the xbb yourself? — Ulrike Fischer, Jan 07 '19 at 19:53
@UlrikeFischer : Thank you. It would be nice if such a thing would already exist, but maybe I will have to homebrew something myself based on graphics code. — AlexG, Jan 07 '19 at 19:58
actually main thing you'd have to change is the code that makes it stop reading the file once it has found a bounding box.... although if you know it's a xbb file with that format rather than arbitrary eps file, it might be as easy to simply \input it rather than use the \read loop from graphics — David Carlisle, Jan 07 '19 at 20:12
@David , do you mean \input{test.xbb}? It's all commented lines, does it read anything at all? — AlexG, Jan 07 '19 at 20:17

David Carlisle · Accepted Answer · 2019-01-07T21:05:43.813

5

\documentclass{article}

\begin{document}


{%
\def\%#1:#2@{\expandafter\xdef\csname ZZ#1\endcsname{#2}}%
\endlinechar`\@ %
\catcode`\%=0 \sbox0{\input{test.xbb}}}%


Pages: \ZZPages
\end{document}

edited Jan 07 '19 at 21:05

answered Jan 07 '19 at 20:19

David Carlisle

757,742

Would you please explain why \input must be placed into an sbox? To prevent any typeset output? – AlexG Jan 07 '19 at 20:35
@AlexG try without:-) yes as you say it throws away any accidental typeset result, in fact you get a typeset @ from the final newline, which could be avoided in other ways but.... – David Carlisle Jan 07 '19 at 20:36
Ok. Very smart! And what about the double percent sign in the input? I can see only one % in \def\%... – AlexG Jan 07 '19 at 20:39
@AlexG if % has catcode 0 (escape character ) then %% references the same command as \% the command with name % just as \\ references the command with name \ – David Carlisle Jan 07 '19 at 20:42
Thank you, @David. I think I got it (after 5 reads or so :-) ). – AlexG Jan 07 '19 at 20:47
What is the sense of the % (=escape chars) at the end of the lines? – Ulrike Fischer Jan 07 '19 at 20:53

How to read %%Pages:... from *.xbb file

1 Answers1