[DejaVu-bugs] [Bug 9038] New: Equivalent Unicode sequences rendered differently with DejaVu

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https://bugs.freedesktop.org/show_bug.cgi?id=9038          
     
           Summary: Equivalent Unicode sequences rendered differently with
                    DejaVu
           Product: DejaVu
           Version: unspecified
          Platform: PC
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: General
        AssignedTo: dejavu-bugs at lists.freedesktop.org
        ReportedBy: roozbeh at farsiweb.info


Some cannonically equivalent Unicode sequences are rendered differently when
using some (all?) Deja Vu fonts. This makes the fonts not conforming to the
Unicode standard, as the standard requires all canonically equivalent sequences
to be rendered the same way.

A short list of some of the cases I discovered follows. I didn't do a thorough
analysis:

U+0374 = U+02B9, but the glyphs are different: ʹʹ
U+0387 = U+00B7, but the glyphs are different: ··

I think that for each of such cases, DejaVu should select the most appropriate
of the two shapes (or one in the middle) and then create two CMAP entries from
the two characters to the same glyph (or make one use glyph references to the
other). In the case the characters really need to appear differently in Greek
contexts, DejaVu should add the greek alternates under names such as
"periodcentered.greek" and use the appropriate OpenType features to handle this.

Of course, it may be said that the rendering engines should take care of Unicode
equivalence, instead of passing the character directly to the font. Even if that
is the desired behavior, a rendering engine that normalizes strings to, say, NFC
before passing it to the font layout subsystem, will never display the Greek
forms of the glyphs (U+0374 and U+0387) and will always use U+00B7 and U+02B9 forms.          
     
     
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