[gs-bugs] [Bug 691861] PDF does not display

bugzilla-daemon at ghostscript.com bugzilla-daemon at ghostscript.com
Mon Jan 17 13:26:04 UTC 2011


http://bugs.ghostscript.com/show_bug.cgi?id=691861

--- Comment #9 from Ken Sharp <ken.sharp at artifex.com> 2011-01-17 13:26:00 UTC ---
(In reply to comment #8)
> Ken, I am just a user of pdf software and beyond considering the "should" and
> "should-not" of pure pdf interpretation. All I can see is that all other pdf
> viewers do automatically and as a matter of course what you say cannot be done.
> And furthermore that you define "cannot be done" as "can be done if the
> equivalence is specified in a text file".

Not exactly. I'm saying that you cannot replace a CIDFont with a Font. That is
definitely the case. There is no 'equivalence' here, you can load a TrueType
font in such a way as to mimic a Font, or to mimic a CIDFont. If you load it as
a Font, you can't then decide to use it as a CIDFont.

As you've pointed out, the 'text' file is in fact a PostScript program. If you
run the font through one program you get a PostScript Font, if you run it
through a different program you get a CIDFont.

Other applications can, like Ghostscript, use a TT font on disk as if it were a
CIDFont. GS can do this if you 'install' the font correctly (ie add it to
cidfmap). Clearly other applications are doing something like this. That is,
they are using the existing TrueType font as a CIDFont, they aren't using a
Font as a CIDFont.

Essentially they are doing automagically what I'm saying you need to do with
GS.

(NB When I say 'Font' I mean a PostScript or PDF font object, I do not mean a
TrueType font file, a PostScript Font is quite different from a PostScript
CIDFont)


> Can't you see that you are not being very user-friendly? That your product
> lacks an algorithm that all the other viewers have implemented?

Yes, its not user-friendly, PostScript never was, and at heart Ghostscript is
still a PostScript engine.

This also leads to part of the problem. Ghostscript (unlike Adobe Acrobat)
processes both PostScript *and* PDF. Anything we do needs to be compatible with
both. There are certain assumptions you can make if you only intend to handle
PDF which you cannot make if you also expect to handle PostScript. 

I would also point out that there are things you can do, or support, if you
only intend to run on a limited number of platofrms, like Adobe, which we can't
do because we support a whole range of operating systems, and we just don't
have the resources to devote to all of them. And our commercial customers, who
understand these issues, have their own solutions to font installation, and our
commercial customers have first call on our resources. 

The Ghostscript application isn't really a 'product' as such, its a useful
example of how to interface with Ghostscript, and it has sufficient
functionality that many people have found it to be useful as-is.

The only way to address your problem is to add the fonts to Ghostscript as
CIDFonts. Currently this is not done at installation time, I don't deal with
the installers  but its possible that someone could come up with a way to
install the fonts as CIDFonts when GS is installed (it already does install the
TT fonts as fonts). The information probably wouldn't be correct, but it might
be sufficient to work, sometimes. This would not help you if you install fonts
after installing Ghostscript of course.

Anyway, that would be a separate enhancement request, please feel free to open
such a request (the component would be config/Install in this case)

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