CI checks failed — I'm investigating the error. Please let me know if you can see the issue from your end or how can i resolve it. Thank you!

The doc build failure appears to be a problem with linking to pandas' documentation so not caused by this PR. However, the build was successful enough that we can look at the relevant thumbnails here:
https://output.circle-artifacts.com/output/job/ce929f36-3f22-414e-8793-6809dc5e88da/artifacts/0/doc/build/html/gallery/misc/index.html

Multpage PDF is still showing the default thumbnail, not the one you are trying to add. I'm also not sure how useful the proposed image is. If a user is actively looking for guidance how to make a multipage pdf, will a line plot indicate that this is the place to click?

Hey @AMAN194701, I took a look at why the thumbnail isn't showing up in the CI build.

The issue is that sphinx_gallery_thumbnail_path is placed on line 1, before the module docstring. Sphinx Gallery only picks up this directive when it appears as a comment below the docstring (see the Sphinx Gallery docs for the expected placement).

Here's the fix — just move the directive after the imports:

-# sphinx_gallery_thumbnail_path = '_static/multipage_pdf_thumbnail.png'
 """
 =============
 Multipage PDF
 =============
 ...
 """

 import datetime

 import matplotlib.pyplot as plt
 import numpy as np

 from matplotlib.backends.backend_pdf import PdfPages
+
+# sphinx_gallery_thumbnail_path = '_static/multipage_pdf_thumbnail.png'

Regarding @rcomer's point about the thumbnail image — that's a fair consideration. Since this example produces three different plots saved into a PDF, the "Page One" line plot does represent what the example actually generates. But it might also be worth following the discussion on #17479 about whether a custom default thumbnail via default_thumb_file would be a better global solution for all the missing-thumbnail cases.

Thank you @rcomer and @Ker102 for the feedback! I'll move the directive to after the docstring right away and push the fix

The thumbnail is now showing correctly in the built docs as you can see here: https://output.circle-artifacts.com/output/job/cf9ec523-efed-4d19-8358-c87be23e2f6c/artifacts/0/doc/build/html/gallery/misc/index.html. The fix was to move the sphinx_gallery_thumbnail_path directive to after the imports as suggested by @Ker102. The CI failure appears to be the pre-existing pandas documentation 404 issue as mentioned by @rcomer, not related to my changes.

Thanks for working on this, but I agree w/ @Ker102 and @rcomer that the line plot isn't an informative thumbnail here. I'd either go w/ something custom to this image (an image of a multi page PDF w/ an open license) or a default "no image" to indicate the example isn't broken.

Thank you @story645! Should I use the default 'no image' approach — would that mean setting up the global default_thumb_file in conf.py as suggested by @rcomer, or should I create a custom image of a multi-page PDF? Happy to go with whatever works best!

Happy to go with whatever works best!

I dunno, propose examples of both and see what folks like? I'm sorry that's more work, but this is one of those things I doubt anyone will have strong opinions on until they see things to have opinions on.

Thank you @story645! I'll try both and share here so everyone can give feedback.

hey @rcomer @story645 the pr_clean check is failing because i added and then updated the same image in the PR. should i squash the commits to fix this?

hould i squash the commits to fix this?

Yes

Here are both options for feedback!

option 1 - custom multipage pdf design (already showing in PR build): [ https://output.circle-artifacts.com/output/job/6d1d0642-aa09-49cb-a776-5e1e4f04a444/artifacts/0/doc/build/html/gallery/misc/index.html ]

option 2 - simple no preview placeholder:

which one works better? @story645

I like option 1.

Could this be an svg so that it also looks good on high-res screens? To be checked whether sphinx-gallery supports this.

Thanks @timhoffm for the suggestion!!
I’ll check whether Sphinx-Gallery supports SVG thumbnails properly, and try converting the current design to SVG to see how it renders in the gallery and I’ll update here once I test it.

Thanks @timhoffm and @story645 for the suggestion !

I checked whether Sphinx-Gallery supports SVG thumbnails — it does. Converted the thumbnail from PNG to SVG so it renders sharply on high-res screens.
Here's how it looks:

And here's the gallery page from the CI build: https://output.circle-artifacts.com/output/job/445260f0-2a71-4926-ab4a-75e23f438a5f/artifacts/0/doc/build/html/gallery/misc/index.html

All CI checks are passing ✅

I like the new svg image but it seems quite small in the gallery compared with other images. Would reducing white space around the edges help that?

Thanks @rcomer !
Yes, that makes sense — I'll reduce the white space around the edges so the image fills the thumbnail better. I will push a fix shortly

Updated the thumbnail — reduced white space so it fills the card better. Here's how it looks in the CI-built gallery:

Built docs: https://output.circle-artifacts.com/output/job/887e62eb-9252-4c7a-b91b-2b6e596394f6/artifacts/0/doc/build/html/gallery/misc/index.html
@rcomer @timhoffm @story645

Thanks @story645! Yes, I made the SVG myself from scratch — it's original work.