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

[Ray Molenkamp]

I can't say I'm super thrilled to build cairo on windows,
but if that's the direction we want to go, so be it.

--Ray


On 2020-12-09 11:19 a.m., Brecht Van Lommel via Bf-committers wrote:
> I'm not sure there exists a simple utility to convert SVG to PDF that we
> could include, if we want to go that way?
>
> Inkscape uses Cairo for PDF writing, that could be a more actively
> maintained alternative.
> https://www.cairographics.org/
>
> It has also been proposed to be added to handle Wayland window decorations
> in D7989, so it would let us solve both problems with one library.
>
>
> On Wed, Dec 9, 2020 at 11:46 AM Antonio Vazquez via Bf-committers <
> bf-committers at blender.org> wrote:
>
>> 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
>>> _______________________________________________
>>> Bf-committers mailing list
>>> Bf-committers at blender.org
>>> https://lists.blender.org/mailman/listinfo/bf-committers
>>>
>> _______________________________________________
>> Bf-committers mailing list
>> Bf-committers at blender.org
>> https://lists.blender.org/mailman/listinfo/bf-committers
>>
> _______________________________________________
> Bf-committers mailing list
> Bf-committers at blender.org
> https://lists.blender.org/mailman/listinfo/bf-committers