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https://issues.apache.org/jira/browse/PDFBOX-4106?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16471604#comment-16471604
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Tilman Hausherr commented on PDFBOX-4106:
-----------------------------------------
So the problem is that a TrueTypeFont object could be reused by several
threads, and the gsub feature vrt2 may be enabled in one and disabled in
another?
Re "fonts in FontBox must be thread safe" - this is not yet perfect. I have
been having trouble on some of my systems with Standard 14 fonts being used by
several threads. It happens only every 10 times, and recently even less because
one AIOOBE is avoided.
> Vertical text creation
> ----------------------
>
> Key: PDFBOX-4106
> URL: https://issues.apache.org/jira/browse/PDFBOX-4106
> Project: PDFBox
> Issue Type: Bug
> Components: FontBox, Parsing, Writing
> Reporter: Aaron Madlon-Kay
> Assignee: Tilman Hausherr
> Priority: Major
> Labels: embed, gsub, parsing, vertical
> Fix For: 2.0.9, 3.0.0 PDFBox
>
> Attachments:
> 0001-Add-OpenTypeScript-class-to-get-OT-script-tags-for-c.patch,
> 0002-Optimize-Unicode-script-storage-and-lookup.patch,
> 0003-Parse-GSUB-table.patch,
> 0004-Abstract-cmap-lookup-into-an-interface.patch,
> 0005-Implement-GSUB-substitution-on-TrueTypeFont.patch,
> 0006-Use-vhea-vmtx-to-fix-vertical-displacements-in-PCIDF.patch,
> 0007-Add-factory-methods-for-loading-TTF-as-vertical-font.patch,
> 0008-Implement-vertical-metrics-support-when-embedding-subsetting.patch,
> FIX-0001-PDFBOX-4106-Remove-early-outs-leading-to-spurious-wa.patch,
> FIX-0002-PDFBOX-4106-Document-GlyphSubstitutionTable-public-m.patch,
> FIX-0003-PDFBOX-4106-Correct-deltaGlyphID-data-size.patch,
> FIX-0004-PDFBOX-4106-Remove-unnecessary-vertical-displacement.patch,
> FIX-0005-PDFBOX-4106-Remove-duplicate-DW2-creation.patch,
> FIX-0006-PDFBOX-4106-Fix-non-embedded-vertical-font-rendering.patch,
> FIX-0007-PDFBOX-4106-Fix-incorrect-parsing-of-W2-first-format.patch,
> FIX-0008-PDFBOX-4106-Rename-misleading-field.patch,
> FIX-0009-PDFBOX-4106-Allow-retrieving-vmtx-topSideBearing.patch,
> FIX-0010-PDFBOX-4106-Correct-vmtx-embedding-for-proportional-.patch,
> sample_code.txt, vertical.pdf
>
>
> I needed to output vertical Japanese text, but was stymied by several
> limitations:
> * No API to load a TTF as Identity-V encoding
> * No support for 'vert' glyph substitution
> * No support for vertical metrics ('vhea' and 'vmtx' tables are parsed but
> not used at all)
> I have attached a series of patches that implement the above features.
> Highlights:
> * The GSUB glyph substitution table is parsed (limitation: type 1 lookups
> only; this is sufficient for many features including 'vert'/'vrt2' vertical
> glyph substitution)
> * Cmap lookup makes use of GSUB when features are enabled on a TTF
> * 'vhea' and 'vmtx' metrics are applied to PDCIDFont when appropriate, and
> are embedded/subsetted correctly through the DW2/W2 CIDFont dictionary
> * An API has been added for loading a TTF as a vertical font, setting
> Identity-V encoding and enabling 'vert'/'vrt2' substitution
> Each patch could approximately be split out into a separate ticket, if
> desired.
> Also attached is some sample code that exercises these patches and
> illustrates the effect of vertical glyph positioning. The sample output PDF
> is also attached.
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