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fix(compress): stop Ghostscript from turning pages in pass A - #210
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Pass A of Compress runs Ghostscript pdfwrite with -dPDFSETTINGS and no AutoRotatePages switch, so gs turns pages by the direction of their text. /ebook, the default level in PDFApps, implies /All: it applies one rotation, that of the document's dominant text, to every page. /screen implies /PageByPage: it turns each page to the direction of its own text. Either way the user can get pages in an orientation the source did not have. Pass -dAutoRotatePages=/None right after -dPDFSETTINGS, on every level. Measured with gs 10.05.0 on Windows and gs 10.06.0 on WSL Ubuntu, with identical results on both: - two pages, page 1 with horizontal text and page 2 with text at 90 degrees: without the switch, /ebook turned both pages 90 degrees clockwise, leaving page 1 on its side, and /screen left page 1 alone and turned page 2; - page 1 stored with /Rotate 90: without the switch, /ebook left that page upside down; - with the switch, no page turned on either version or preset. The code comment also lists gs 9.55.0 among the versions it was measured on; that version was not re-checked for this change. tests/test_compress_gs_autorotate.py adds 11 tests: 3 check the pass A argv on each level with a faked gs, 8 run the real gs on four fixtures under /ebook and /screen and are skipped when no gs is found. All 11 pass with the switch and all 11 fail without it. Full suite: 1049 passed, 2 skipped. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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Summary
Pass A of Compress runs Ghostscript pdfwrite with
-dPDFSETTINGSand noAutoRotatePagesswitch, so gs turns pages by the direction of their text:/ebook, the default level in PDFApps, implies/All: it applies one rotation, that of the document's dominant text, to every page./screenimplies/PageByPage: it turns each page to the direction of its own text.This changes the orientation the user sees. The fix passes
-dAutoRotatePages=/Noneright after-dPDFSETTINGS, on every level.Files:
app/utils.py,tests/test_compress_gs_autorotate.py(new, 11 tests).Measurements
gs 10.05.0 on Windows and gs 10.06.0 on WSL Ubuntu gave identical results.
/ebook/screen/Rotate 90/ebookThe code comment also lists gs 9.55.0 among the versions it was measured on; that version was not re-checked for this change.
Tests
/ebookand/screen, and are skipped when no gs is found.🤖 Generated with Claude Code