[DejaVu-bugs] [Bug 50848] New: Seams with disjoint composite

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=50848

             Bug #: 50848
           Summary: Seams with disjoint composite
    Classification: Unclassified
           Product: DejaVu
           Version: unspecified
          Platform: Other
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: medium
         Component: General
        AssignedTo: dejavu-bugs at lists.freedesktop.org
        ReportedBy: freedesktop at behdad.org


Problem I reported to FreeType and Werner's response:

> > I was playing with Unicode box characters, and noticed that DejaVu
> > Sans creates the glyph for ▟ out of three quadrant boxes.  At
> > different sizes I can see very noticeable seams where the sub-glyphs
> > meet.  I thought FreeType would handle these cases better, but seems
> > like I'm wrong.  Any ideas?  Does FreeType combine all contours
> > together and rasterize them in one pass, or raster them separately
> > and combine?

They are rasterized in a single pass.  However, the DejaVu font
doesn't contain the necessary bytecode to properly handle the rounding
issues which inevitably happen if subglyphs are combined -- in ftview,
press key `f' to force autohinting, and you won't see seams.  I've
just confirmed that exactly the same issue is present with the Windows
rasterizer, so it's not a FreeType problem.

Of course, a much simpler (and probably even better) solution is to
avoid subglyphs if they touch at longer lines.


    Werner

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