[Libreoffice-bugs] [Bug 52582] New: Problem with combining unencoded characters in Brahmi Graphite font

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=52582

             Bug #: 52582
           Summary: Problem with combining unencoded characters in Brahmi
                    Graphite font
    Classification: Unclassified
           Product: LibreOffice
           Version: 3.7.0.0.alpha0+ Master
          Platform: Other
        OS/Version: All
            Status: UNCONFIRMED
          Severity: normal
          Priority: medium
         Component: Writer
        AssignedTo: libreoffice-bugs at lists.freedesktop.org
        ReportedBy: samjnaa at gmail.com


Created attachment 64775
  --> https://bugs.freedesktop.org/attachment.cgi?id=64775
Test material to reproduce and test the bug

While working on a proposal to encode two characters to Brahmi
(https://sites.google.com/site/jamadagni/files/utcsubmissions/12226-brahmi-two-tamil-characters-proposal.pdf),
I found that some versions of LibO on some platforms had a bug by which an
unencoded codepoint would not combine properly.

I had proposed to disunify the Tamil Brahmi virama from 11046 and encode it at
11070, and likewise to disunify the Tamil Brahmi LLA from 11034 and encode it
at 11071.

However, if I map the glyphs in my fonts to 11070 and 11071, problems are
created. See the attachment. It contains a Graphite Brahmi font (under the OFL)
in glyph-only and Graphite-enabled forms. The GDL is also included. 

Test ODTs and the renderings (as PDF) on LibO 3.5.4 on Win XP, LibO 3.5.3 on
Linux (Kubuntu Precise) and LibO 3.7.0alpha
(LibO~master~2012-06-14_22.09.53_3.7.0alpha0) on Win XP are provided. 

Only LibO 3.5.4 on Win XP does not have any problems with the un-encoded
mappings. LibO 3.5.3 on Linux and LibO 3.7alpha on Win XP do not correctly join
LLA to the vowel signs. (LLA line highlighted in blue.) 

Perhaps some versions of LibO make some assumptions about the encoded or
non-encoded status of characters? Which is why 11071 Tamil Brahmi LLA does not
combine properly? But this does not explain why I had no problems with the
equally un-encoded 11070 Tamil Brahmi Virama? Or how the version numbers (see
above) work out (I mean, bug seen in 3.5.3 and 3.7 but not in 3.5.4)?

Graphite by definition does not make any assumptions about the encoding or
non-encoding of any characters. If LibO is to provide true Graphite
integration, it should also not make any assumptions about input characters
when they are being rendered using Graphite.

Please fix this so that we can use LibO for rare Indic scripts via Graphite
(which we can't expect OpenType support for).

Thank you for your great work on LibO and Graphite!

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