matplotlib-devel Mailing List for matplotlib

[This discussion somehow wandered onto matplotlib-user. I'm bringing it back 
over to the dev list.]

On Monday 24 April 2006 16:30, Alan G Isaac wrote:
> On Mon, 24 Apr 2006, Christopher Barker apparently wrote:
> > I think it might use dvips or something to do that. rather than
> > reading and rendering the DVI itself.
>
> That is not my understanding,
> which however is limited.

PyX does read dvi files. I'll bet they ported dvitype to do so (PyX 
distributes a script called dvitype.py.)

> PS I have tried to reopen the discussion with the PyX
> developers.  I'll post any useful outcomes.

Their webpage states that they would consider relicensing, but when I talked 
to them, they were unwilling to release under a BSD-compatible license. 
However, we dont need all of PyX to be relicensed, and I did not make that 
clear to the PyX authors. If they would consider relicensing a subset of 
their code, it would be extremely helpful.

On Monday 24 April 2006 10:48, Jouni K Seppanen wrote:
> Darren Dale <dd...@co...> writes:
> > The basic approach is to extract the font layout information from the
> > dvi files. LaTeX could be the only dependency.
>
> Great! Another possibly useful reference is
>
> http://www.tug.org/tex-archive/dviware/driv-standard/level-0/dvistd0.pdf
>
> and the documents in driv-standard/papers. dvi is apparently pretty
> difficult to parse, as you have to implement a bytecode interpreter to
> keep track of the state.

Thanks Jouni, I was not aware of this document. There are some other packages 
in dviware that could serve as useful examples, like dvitops (there are a lot 
of GPL'd packages too, like dvisvgm and dvipdfmx. Too bad.)

Darren Dale <dd...@co...> writes:

> The basic approach is to extract the font layout information from the 
> dvi files. LaTeX could be the only dependency.

Great! Another possibly useful reference is

http://www.tug.org/tex-archive/dviware/driv-standard/level-0/dvistd0.pdf

and the documents in driv-standard/papers. dvi is apparently pretty
difficult to parse, as you have to implement a bytecode interpreter to
keep track of the state.

-- 
Jouni

>>>>> "Darren" == Darren Dale <dd...@co...> writes:

    Darren> I also discovered that xdvi is OSS compliant, and have
    Darren> started studying that source code as well. I only started
    Darren> writing code to read the dvi information, but I post here
    Darren> to allow people to comment if they are so inclined, and to
    Darren> share the dvitype example with anyone who is interested. I
    Darren> have compiled the tex file, converted it to pdf, and
    Darren> posted the result at
    Darren> http://staff.chess.cornell.edu/~dale/matplotlib/dvitype.pdf.

This is very good stuff Darren -- it would be really nice to have a
python interface to dvi files under a BSD compatible license.
matplotlib sitting on top of my two favorite runtimes: python and TeX.

I think it is a shame that a lot tools built on top of TeX (web2c,
pyx, ...) have a more restrictive license than TeX itself, so this
would be a very useful piece of code.

JDH

Thanks for doing this Darren.  Keep up the good work!

On 4/24/06, Darren Dale <dd...@co...> wrote:
> This weekend I took the first small step towards improving usetex and
> eliminating the need for PSFrag and dependencies like ghostscript. This i=
s
> necessary in order to provide usetex support accross backends (like pdf a=
nd
> svg). The basic approach is to extract the font layout information from t=
he
> dvi files. LaTeX could be the only dependency.
>
> Wikipedia has an article about the dvi specification:
> http://en.wikipedia.org/wiki/DVI_file_format, which has a link to a reall=
y
> useful file called dvitype.web. This file contains the full dvi specifica=
tion
> and can be converted into a plain tex file using weave:
> http://www.ctan.org/tex-archive/systems/knuth/texware/dvitype.web
>
> dvitype.web also contains a well documented pascal program illustrating h=
ow to
> read dvi files correctly and convert them into symbolic form. It was mean=
t as
> a guide to programmers developing dvi-related software. It includes a sec=
tion
> on extracting the necessary information from tfm files, and other issues
> related to fonts.
>
> I also discovered that xdvi is OSS compliant, and have started studying t=
hat
> source code as well. I only started writing code to read the dvi informat=
ion,
> but I post here to allow people to comment if they are so inclined, and t=
o
> share the dvitype example with anyone who is interested. I have compiled =
the
> tex file, converted it to pdf, and posted the result at
> http://staff.chess.cornell.edu/~dale/matplotlib/dvitype.pdf.
>
> Darren
>
>
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This weekend I took the first small step towards improving usetex and 
eliminating the need for PSFrag and dependencies like ghostscript. This is 
necessary in order to provide usetex support accross backends (like pdf and 
svg). The basic approach is to extract the font layout information from the 
dvi files. LaTeX could be the only dependency.

Wikipedia has an article about the dvi specification: 
http://en.wikipedia.org/wiki/DVI_file_format, which has a link to a really 
useful file called dvitype.web. This file contains the full dvi specification 
and can be converted into a plain tex file using weave: 
http://www.ctan.org/tex-archive/systems/knuth/texware/dvitype.web

dvitype.web also contains a well documented pascal program illustrating how to 
read dvi files correctly and convert them into symbolic form. It was meant as 
a guide to programmers developing dvi-related software. It includes a section 
on extracting the necessary information from tfm files, and other issues 
related to fonts. 

I also discovered that xdvi is OSS compliant, and have started studying that 
source code as well. I only started writing code to read the dvi information, 
but I post here to allow people to comment if they are so inclined, and to 
share the dvitype example with anyone who is interested. I have compiled the 
tex file, converted it to pdf, and posted the result at 
http://staff.chess.cornell.edu/~dale/matplotlib/dvitype.pdf. 

Darren