Exported layer visibility not respected by Inkscape and Affinity Designer for some patterns

[courtneypattison]

Reported in projectors for sewing. Tagging @cfcurtis in case you have any ideas! I'll try and find a few examples to link to here. I just exported a pattern and used it in Inkscape a couple of days ago so it's not happening for all patterns.

[courtneypattison]

I had a little bit of time to look into this issue this morning and noticed it happens when multiple pages are stitched. If it's just a single page projector file, then Inkscape sees all the layers and shows visibility correctly. If it's a multi page PDF, then the layers don't get imported correctly, i.e. don't show up in the Inkscape layer menu. Instead of being layer based groups, the paths are grouped by pages. Weirdly, the PDF importer preview in Inkscape correctly shows the selected visible layers in both cases.

[courtneypattison]

Just found a workaround for now: convert to SVG using https://pdf-to-svg.web.app/ after exporting from PP, then load into Inkscape and presumably AD (I don't have it).

[cfcurtis]

Thanks for the tag! I'm away (at sewing camp!) right now, but I can take a look at this next week. My guess is that it's either an upstream issue with the PDF library, or some some problem with converting the pages to xobject during stitching.

[courtneypattison]

Thanks for the tag! I'm away (at sewing camp!) right now, but I can take a look at this next week.

Sewing camp?! That must be awesome. No rush at all!

[cfcurtis]

Sewing camp?! That must be awesome. No rush at all!

It was amazing to actually get time to sew for once! And to be surrounded by people who are just as excited about sewing.

Back to the issue... I did a few tests and I'm fairly confident it's an Inkscape/AD import issue, not an export issue. I tried:

• Stitching and setting layer visibility in PDFStitcher
• Stitching in PDFStitcher and setting layer visibility in Adobe Acrobat
• Stitching in Pattern Projector and setting layer visibility in Adobe Acrobat
• Importing in Inkscape 1.4 and current dev master

All of these things gave the same result.

I looked at the Inkscape source, and I think what's happening is the layers are getting ignored after they're converted to a form XObject. The function that loads layer info seems to only be called for each page, not for the page-within-a-page, so in this very weird edge case, layer information is lost. I expect Affinity does something similar.

I reported the issue to Inkscape and I'll see what I can do about fixing it.

[courtneypattison]

Thank you so much @cfcurtis !

[cfcurtis]

Update: this spiralled into quite a few changes to the PDF import process in Inkscape, which were finally merged in last week! Eventually (v1.5 probably) you'll be able to choose how groups are created: "by layers" to preserve PDF layers as the top-level groupings, or "by object" to create groups for PDF objects such as pages (the current behaviour).

The current master branch is rather unstable, but you can test it out by downloading the build artifacts from the ci pipeline page - click on the download link dropdown at the far right of the most recent finished pipeline and select your OS:

[courtneypattison]

That's amazing @cfcurtis !!! I tried to download the latest version but it seems like it's broken right now. I'll try again on another day.

I was just feeling grateful for all your hard work yesterday when PP struggled with stitching a pattern and PDFStitcher handled it no problem. Thank you thank you!