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Valeriy E. Ushakov
Tue, 2 Dec 1997 19:47:54 +0300
On Tue, Dec 02, 1997 at 11:49:09AM +1100, Darrin Smart wrote:
> Valeriy E. Ushakov wrote:
> > And a rudimentary PDF backend without all the bells and whistles can
> > share a lot of code with PS backend. I think 99.9% of engine code can
> > be shared as the imaging model is the same, the differences are in the
> > output format.
> It would be a little more complex than this. A lot of the PostScript
> specifics are actually in the package definitions. You also need to grep
> for @BackEnd in these. And actual postscript functions are defined in
> some of these too.
Yes, I intentionally oversimplified the problem :-)
> In addition, if PDF is a binary format it could be rather difficult
> to write packages to output them.
PDF 1.0 was ASCII only. PDF 1.1 specification states (I have 1.1 spec
in text, I have 1.2 spec in PDF only, so I can't paste from it from
| A PDF file is either a 7-bit ASCII file or a binary file. If it is
| a 7-bit ASCII file, only the printable subset of the 7-bit ASCII
| code plus space, tab and newline (return or linefeed) is used. If
| it is a binary file, the entire 8-bit range of characters may be
PDF backend can stick to producing plain ASCII. A separate converter
can (can it?) later be used to convert PDF output from Lout into
binary format, to apply encription etc.
> Or you could write a XML-based specification for the backend which used
> a declaritive drawing model rather than a programming language which
> would make writing filters to various formats easier.
Hmm, sounds like SPDL, isn't it?
SPDL is ISO Standard Page Description Langauge which is a mixture of a
subset of PostScript structured with SGML. Check the SGML Page at
http://www.sil.org/sgml/sgml.html and go to "related standards"
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- PDF, P.J. Kersten, 1997/12/01
- Re: PDF, Valeriy E. Ushakov, 1997/12/01
- Re: PDF, Darrin Smart, 1997/12/01
- Re: PDF,
Valeriy E. Ushakov <=