"It would be absoltely wonderful if as part of your work you ended up writing 
even a rudimentary content stream parser that was self contained enough to be 
included in PoFoFo ."

Great. I would love to contribute a content stream parser. I don't quite know 
what this means yet, but perhaps we can talk about the proper API (from your 
perspective). 

With your mentoring I may be able to contribute a component to the podofo 
project that you find useful.

 "Looking at the attached PDF, I think it's safe to say you can handle a very 
restricted subset of PDF and still be OK. I begin to see why you're doing it 
the way you are. A content stream parser for that shouldn't be too hard to 
write at all by the looks."

This was my impression/hope as well. I want to start simple, and yet put myself 
on a road to increasingly understand/use pdf.

Now that you've seen the pdf files that im currently interested and understand 
that I'm willing to put in the effort to "do this right", and to contribute 
something back to the community, please help me to understand the appropriate 
initial characteristics (API) of the "content stream parser".


Thanks for all the help!
Dave

-----Original Message-----
From: Craig Ringer [mailto:[EMAIL PROTECTED] 
Sent: Wednesday, November 07, 2007 1:48 PM
To: Sargrad, Dave
Cc: [email protected]
Subject: Re: [Podofo-users] trying to build podofo using visual studio

Sargrad, Dave wrote:
> I understand that podofo is not a renderer.. I want it specifically 
> because it does not render! We have some very specific rendering 
> requirements.

Glad to hear it. I just wanted to make sure you weren't under any 
misapprehensions.

> My first-use intent (relative to podofo) is to build a document viewer 
> that leverages the ogre renderer, and to use podofo to parse/interpret 
> the objects contained within the pdf file.

That sounds fairly reasonable. Your main issue will be that at present PoDoFo 
won't help you parse content streams. You will need to parse content streams as 
part of rendering a PDF.

It would be absoltely wonderful if as part of your work you ended up writing 
even a rudimentary content stream parser that was self contained enough to be 
included in PoFoFo . This would probably be wise anyway, rather than mixing 
your basic content stream parsing with rendering code.  I'd be happy to lend my 
limited time and more limited skill to help with that - and I'm one of those 
freaks who actually *likes* cleaning up and integrating code, fiddling with 
build systems, etc.

Looking at your PDF after uncompressing it, you might be in an ideal situation 
for a simple content stream parser to be very handy.

> I took a quick look at libpoppler and I believe it makes very specific 
> rendering assumptions, so my approach was to use podofo to interpret 
> the contents of the pdf file, and I would tackle all the higher level 
> rendering.

Fair enough.

> In my case rather than libpoppler, I will be using Ogre as the 
> rendering engine. I can guarantee that I don't yet fully appreciate 
> the work involved to get to the point where I can render the objects 
> that PoDoFo draws from any particular PDF file. I believe there is 
> quite a bit of work, and yet am hoping that I can prototype something 
> in fairly short order.

I sincerely hope so. Rendering PDF is very complicated, and that's if you 
assume most PDF is correct (which is far from the truth). The number of 
verisons and options doesn't help. That said, it's hardly impossible.

If you can limit yourself to a certain subset of PDF, at least initially, 
things might be much easier. Some things are worth getting right from the start 
IMO (ICCBased & CMYK colour, for example) but I wouldn't be too surprised if 
you were able to get away without handling things like layer blend modes 
initially. Then again, for all I know they're easy with your rendering backend.

Looking at the attached PDF, I think it's safe to say you can handle a very 
restricted subset of PDF and still be OK. I begin to see why you're doing it 
the way you are. A content stream parser for that shouldn't be too hard to 
write at all by the looks.

%PDF-1.4
%»°°« Layton Graphics, Inc. pdf++ library
1 0 obj
<< /CreationData (D:20070928141754) /Producer (dgn2pdf)

I presume dqn is a custom format in use in your industry, and that you don't 
have access to the original files the PDFs were created from? 
(Just curious...).

Speaking of "nice to have" ... wish our stream interfaces were usable as 
iostream buffers so they could be processed with C++ stream operations... . 
Unforutnately implementing new iostreams interfaces is rather far from fun.

--
Craig Ringer

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