[erlang-questions] ErlGuten

Tue Sep 25 18:51:10 CEST 2018

Hi Theepan,

Other than display in my demo PDF, I haven't worked much with images. 

The issues you've run across seem serious. Getting at the root of the problems will likely involve a deep dive into both the PDF reference manuals and core ErlGuten source code. 

As I noted in my earlier email, ErlGuten source code is very challenging. It would benefit significantly from re-write, possibly refactoring in some cases and definitely systematic documentation of functions and parameters.

I'm not confident that my skills are up to this. My take is that it would require some amount of community effort to put ErlGuten/erlpress_core on a solid, maintainable base. I would dearly love to see this happen.

Is there a CS major or intern out there with time to take on the challenges?

Joe showed us the way and I, for one, am deeply grateful. Given that PDF is a significant standard in the print media world, Erlang deserves to have a world-class library and suite of tools to generate PDF documents and decode them back into Erlang structures.

This will take community effort.

All the best,

Lloyd

-----Original Message-----
From: "Theepan" <vasdeveloper@REDACTED>
Sent: Monday, September 24, 2018 7:27pm
To: "Lloyd Prentice" <lloyd@REDACTED>
Cc: "Erlang Questions Mailing List" <erlang-questions@REDACTED>, "Joe Armstrong" <erlang@REDACTED>
Subject: Re: [erlang-questions] ErlGuten

Wanted to add to the issues the reasons --

** When some JPEG image is embedded into the PDF, it turns out dark in the
generated PDF file [Happens due to CYMK color profile.]
** When some PNG file is embedded, it takes too long (unto 5 minutes) to
generate the PDF file. Debugging shows that the delay is on defilter(Method
, Line1, Line2, Offset, Width, Iter) of eg_pdf_image module.[Happens due to
Alpha channel presence]

On Tue, Sep 25, 2018 at 4:45 AM Theepan <vasdeveloper@REDACTED> wrote:

> Thanks Lloyd for your detailed explanation on what has been done, and your
> vision for the library. However we are already using ErlGuten in one of our
> production systems, and the issues is mainly with the images.
>
> I will definitely keep an eye on the development of erlpress_core in the
> future, as you seem enthusiastic about making it a lively library.
>
> The issues we have are:
>
> ** When some JPEG image is embedded into the PDF, it turns out dark in the
> generated PDF file
> ** When some PNG file is embedded, it takes too long (unto 5 minutes) to
> generate the PDF file. Debugging shows that the delay is on defilter(
> Method, Line1, Line2, Offset, Width, Iter) of eg_pdf_image module.
>
> Did you come acrsoss this?
>
> Best,
> Theepan
>
>
>
>
>
> On Tue, Sep 25, 2018 at 2:56 AM <lloyd@REDACTED> wrote:
>
>> Hi Theepan,
>>
>> 1. If you look at ErlGuten source, you'll see that function documentation
>> is fairly minimal and many parameters have single character names with
>> little to no documentation. This makes maintenance and revision very
>> difficult. I consider the core ErlGuten modules diamonds-in-the-rough.
>>
>> I also found the high-level page make-up functions provided by Hugh and
>> Carl limited with respect to professional page make-up and, to me at least,
>> a bit confusing.
>>
>> But erlpress_core owes a deep debt and much gratitude to the ErlGuten
>> lineage.
>>
>> erlpress_core is based on Joe's font-handling, justification, and XML
>> parsing code with few if any changes. But it provides map structures to
>> represent nearly all of the PDF objects represented in eg_pdf_op.erl. These
>> map structures incorporate many default parameters so generating PDF
>> documents is syntactically simple and consistent without sacrificing
>> expressive flexibility. You can easily customize display by instantiating
>> map parameters with your own values.
>>
>> You can see most of the PDF objects currently supported by erlpress_core,
>> including boxed text, justification options, and various line and text
>> objects, demonstrated in ep_show_n_tell.pdf and the source in
>> ep_show_n_tell.erl.
>>
>> If you look at the map definitions of the various PDF objects, you'll see
>> how to customize display.
>>
>> At some point if would be good to re-write the base Erlguten modules with
>> more explicit function and parameter documentation, but I'm not up to that
>> at this point. But, anyone looking for a challenge is free to jump in.
>>
>> I'm currently working on tables and text flow across pages (think reports
>> and book chapters). Hope to deliver these features plus much code polishing
>> in the next release coming "real soon now."
>>
>> High on my wish/to-do list are:
>>
>> -- Easy-to_use page-grid design functions
>> -- Imposition (printing multiple page impressions on a single sheet of
>> paper stock)
>> -- Articles and beads (think text jumping across  columns and pages)
>> -- Easy-to-use and expressive page make-up functions
>> -- Example templates for various print formats
>> -- Markdown input
>> -- Support of TTF and OTF fonts
>>
>> Joe Armstrong expressed the following goal when he first announced
>> ErlGuten:
>>
>> "Better than TeX."
>>
>> That's a tall order, yet to be realized. My hope is that erlpress will
>> move the ball further down the field.
>>
>> 2. I haven't done anything with image formats beyond what you'll find in
>> eg_pdf_image.erl. I'd welcome work in that direction.
>>
>> 3. erlpress_core is still at Version 0.01. It's just out. I'm working
>> toward sufficient functionality and stability to support a web application
>> that we have currently under development.
>>
>> 4. I developed erlpress_core on Erlang/OTP 19. It does require support
>> for maps.
>>
>> I see the erlpress_core library as a valuable library for embedding PDF
>> generation into Erlang applications and as the basis for many exciting
>> Erlang-based print production tools.
>>
>> So, Treepan, I appreciate your interest and would welcome your
>> involvement in testing and feature development.
>>
>> I would jump for joy if some Erlang guru were to step forward take on the
>> TTF/OTF support issue. I've done some research and have a few ideas on how
>> expanded font support might be accomplished, but have too little time over
>> the next several months to dig into it.
>>
>> Incidentally, in my previous post my iPad decided it was smarter than me
>> and erroneously corrected my GitHUb address.it should be
>> writersglen/erlPress_core.
>>
>> My intention is to bag the camel case in my next release with luck in a
>> week or two so it should look like writersglen/erlpress_core.
>>
>> All the best,
>>
>> Lloyd
>>
>>
>> -----Original Message-----
>> From: "Theepan" <vasdeveloper@REDACTED>
>> Sent: Monday, September 24, 2018 3:59pm
>> To: lloyd@REDACTED
>> Cc: "Erlang Questions Mailing List" <erlang-questions@REDACTED>, "Joe
>> Armstrong" <erlang@REDACTED>
>> Subject: Re: [erlang-questions] ErlGuten
>>
>> Hi Lloyd,
>>
>> Thank you for your response. I have some quick clarifications --
>>
>> * What are the major improvements made on the source ErlGuten? Did you
>> improve support to different image formats? Any critical bugs fixed?
>> * Is erlPress_core used in commercial applications, specifically of high
>> throughput types?
>> * What is the minimum erlang/OTP version required?
>>
>> Best,
>> Theepan
>>
>>
>>
>>
>>
>>
>> On Mon, Sep 24, 2018 at 6:36 AM Lloyd R. Prentice <lloyd@REDACTED>
>> wrote:
>>
>> > Hi Thepan,
>> >
>> > I’ve undertaken a major revision of ErlGuten called erlPress_core—
>> > announced it on Erlang questions several weeks ago.  It’s available from
>> > GitHub as Writersglen/erlPress_core. I think you’ll find it much more
>> > accessible than the ErlGutens.
>> >
>> > I’ve since been polishing up the code and adding a few new features.
>> After
>> > the launch I learned that camel case is not conventional usage when it
>> > comes to the names of Erlang applications and libraries. So I plan to
>> > release the updated version as erlpress_core. With smooth sailing I
>> hope to
>> > release sometime this week or next.
>> >
>> > All the best,
>> >
>> > Lloyd
>> >
>> > Sent from my iPad
>> >
>> > On Sep 23, 2018, at 8:30 PM, Theepan <vasdeveloper@REDACTED> wrote:
>> >
>> >
>> > Hi Team,
>> >
>> > I see many forks of ErlGuten. Which one is the latest, most stable and
>> > widely used?
>> >
>> > https://github.com/richcarl/erlguten
>> > https://github.com/CarlWright/NGerlguten
>> > https://github.com/hwatkins/erlguten/commits/master
>> >
>> > Best,
>> > Theepan
>> >
>> >
>> > _______________________________________________
>> > erlang-questions mailing list
>> > erlang-questions@REDACTED
>> > http://erlang.org/mailman/listinfo/erlang-questions
>> >
>> >
>>
>>
>>