Bug 170239 - Certain vertical glyphs shifted toward baseline in PDF export
Summary: Certain vertical glyphs shifted toward baseline in PDF export
Status: NEW
Alias: None
Product: LibreOffice
Classification: Unclassified
Component: Printing and PDF export (show other bugs)
Version:
(earliest affected)
unspecified
Hardware: All All
: medium normal
Assignee: Not Assigned
URL:
Whiteboard:
Keywords:
Depends on:
Blocks: Vertical-Text
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Reported: 2026-01-05 22:48 UTC by Jonathan Clark
Modified: 2026-01-15 07:43 UTC (History)
1 user (show)

See Also:
Crash report or crash signature:


Attachments
PNG export (black) overlaid on PDF export (red) (9.90 KB, image/png)
2026-01-05 22:48 UTC, Jonathan Clark
Details
Simple reproducer (7.92 KB, application/vnd.oasis.opendocument.text)
2026-01-05 22:49 UTC, Jonathan Clark
Details
bibisect-linux-64-7.2 (924.06 KB, application/pdf)
2026-01-15 07:42 UTC, Saburo
Details

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Description Jonathan Clark 2026-01-05 22:48:55 UTC
Created attachment 204933 [details]
PNG export (black) overlaid on PDF export (red)

When exporting vertical text to PDF, some characters seem to be positioned slightly to the left of where they should be, when compared to the screen and Microsoft Windows PDF printer.

So far, this behavior has been observed with U+2026 horizontal ellipsis and U+2015 horizontal bar. When used in vertical Japanese text with typical fonts, these characters should appear roughly centered with respect to the preceding text. However, in our PDF export, they are noticeably shifted out of position.
Comment 1 Jonathan Clark 2026-01-05 22:49:49 UTC
Created attachment 204934 [details]
Simple reproducer
Comment 2 Volga 2026-01-06 14:18:07 UTC
For PDF export, any upright glyph in vertical text layout should be keep centered with respect to the vertical baseline of the font, otherwise, if the font does not provide that, the upright glyph should be aligned with the strikethrough metric of the font, or a baseline synthesized from other metrics.

See: https://drafts.csswg.org/css-writing-modes-4/#vertical-metrics
Comment 3 Saburo 2026-01-15 07:42:37 UTC
Created attachment 205054 [details]
bibisect-linux-64-7.2

reproducible
Version: 26.2.0.1 (X86_64)
Build ID: 334ecff79a5ea28464a392deab1041cf2e705201
CPU threads: 2; OS: Linux 6.8; UI render: default; VCL: gtk3
Locale: ja-JP (ja_JP.UTF-8); UI: en-US
Calc: threaded

In the 'Noto Sans CJK JP' font, it was displayed right of center, but now it is aligned left of center.

It was centered in the 'BIZ UD Gothic' font, but is now positioned to the left of center.