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Update pgf baseline image for TeX Live 2025 - #32504
axel-j-larsson wants to merge 1 commit into
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Hi @iccir, just checking back to see if there were any plans on changing the CI to use TeX Live 2025. If not, would it perhaps be a good idea to instead specify which version of it that is expected in the docs? |
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I'm honestly not sure, as this isn't my area of expertise. My instinct would be to pick the TeX Live version with the most users and then xfail the tests on other configurations. Ultimately, all tests either need to pass or be expected to fail. |
PR summary
Fixes issue #29790. Also relates to PR #32478 .
With TeX Live 2025,
test_backend_pgf.pywas failing due topgf_rcupdate2, where a single character had changed location by a pixel:I investigated it and the PGF files generated by
pgf_backend.pywere identical between TeX Live versions. After manually regenerating the PDFs from the same PGF file with both TeX Live 2025 and 2024, I found that their contents differed slightly in regards to object positioning. After additionally manually rasterizing the output with ghostscript (as done in the test), the same one-pixel difference appeared in both the files created by Matplotlib and the ones generated and rasterized manually.It appears that the difference is instead caused by updates in PDFTeX's rendering engine, and would as such not be anything directly caused by a bug in Matplotlib. As such, I determined the most suitable fix would be to update the baseline image. I have also checked the new baseline with TeX Live 2026, and it still passes there.
However, the new baseline does instead fail for TeX Live 2024 (and presumably earlier versions as well). As such, the suitability of this PR depends on what which TeX Live version to support, and in extension which Ubuntu version to support (see #32478).
AI Disclosure
AI was used to help investigate the image difference and generate new PDFs directly with pdfLaTeX. However, the new baseline test results have been verified and reviewed manually.
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