[Bf-committers] GPencil I/O Project: Request to integrate libharu lib to export PDF format

[Antonio Vazquez]

There are several reasons why I decided to use libharu.

* The PDF format is very stable and does not change substantially, so we
are not at great risk due to format changes.
* I already know that this library is not maintained, but since the PDF
format does not change, it does not require much maintenance.
* This library is widely used in other software to generate PDF, so it is
well proven.

Regarding the bugs you comment, I have seen that several have a patch to
solve them, but in any case, the use I make of the library does not include
using images, only a very simple use. I do not expect, in the short or
medium term, to use anything related to appending images, so these bugs do
not affect us at all. Attaching images to a PDF does not make much sense in
our case.

Including a converter from SVG could work, but the problem is that in PDF
we can generate a document with several pages and in SVG I have not seen
that this is supported. Imagine that we want to generate a storyboard with
100 frames ... we would need to export 100 SVG and join them later ... now
that is very simple. We would also have to assess the speed of the
conversion, since now it is all C / C ++ and it is very fast.

The other option I have been considering is to fork libharu and create a
tiny version with the functions we need and remove any appended image
support.

Antonio

El mié, 9 dic 2020 a las 0:46, Campbell Barton via Bf-committers (<
bf-committers at blender.org>) escribió:

> Hi Antonion,
>
> From what I can tell libharu hasn't been very active since 2013, their
> site states they're looking for a new maintainer.
> Would we become the defacto maintainers of this library?
>
> I checked their issue tracker, while many reports are support requests
> and build issues, there are some more serious looking issues too, eg:
>
> https://github.com/libharu/libharu/issues/73
> https://github.com/libharu/libharu/issues/71
> https://github.com/libharu/libharu/issues/63
>
> Is there a significant advantage in integrating a library compared
> with bundling a utility that converts SVG to PDF?
> In this case it could be an optional dependency, or we bundle the
> conversion tool in official releases so PDF support is still
> integrated from a user perspective.
>
> On Wed, Dec 9, 2020 at 6:31 AM Antonio Vazquez via Bf-committers
> <bf-committers at blender.org> wrote:
> >
> > Hi All,
> >
> >
> >
> > As some of you may already know, for version 2.92 we want to focus on the
> > Import and Export processes of Grease Pencil (T83190).
> >
> >
> >
> > Currently, the grease pencil is in some way an "island" in the studios
> > pipeline and we need to add tools to integrate it. Part of these
> > integration processes were the work we did to make image traces (2.91)
> and
> > shortly, video traces (2.92).
> >
> >
> >
> > During the contacts that the members of grease pencil team usually have
> > with 2D studios, they have detected that some commercial software very
> > important in the studios pipeline does not support the import of SVG, but
> > of PDF. In addition, the PDF format allows working in many softwares and
> is
> > very useful for generating storyboards and work in comics.
> >
> >
> >
> > Past weeks, I have been working on a new I/O module for grease pencil in
> C
> > ++ and I already have the SVG Importer (T79875) and the SVG Exporter
> > (T83191) and PDF Exporter (T83192) working. All work has been done on a
> > private branch on my PC.
> >
> >
> >
> > You can see a PDF exporter video here: https://youtu.be/BMm0KeMJsI4
> >
> >
> >
> > To export to PDF I have used an open source library (libharu
> > http://libharu.org/) and would need to integrate that library into
> Blender.
> > This library is very simple (<1.6 MB on Windows) and allows export to PDF
> > easily.
> >
> >
> >
> > Finally, exporting to PDF opens up a world of possibilities and
> especially
> > when the new LineArt module will be integrated into Blender.
> >
> >
> >
> > If we agree to integrate libharu, I can prepare the patch for review the
> > I/O code I did.
> >
> >
> >
> > I would like to hear your opinions.
> >
> >
> >
> > Best Regards,
> >
> > Antonio Vázquez
> >
> > Grease Pencil Team
> > _______________________________________________
> > Bf-committers mailing list
> > Bf-committers at blender.org
> > https://lists.blender.org/mailman/listinfo/bf-committers
>
>
>
> --
> - Campbell
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