Hash :
4694ea2b
Author :
Date :
2009-09-02T13:06:33
Improve vertical metrics calculation (Savannah bug #27364).
The calculation of `vertBearingX' is not defined in the OTF font
spec so FreeType does a `best effort' attempt. However, this value
is defined in the PDF and PostScript specs, and that algorithm is
better than the one FreeType currently uses:
FreeType: Use the middle of the bounding box as the X coordinate
of the vertical origin.
Adobe PDF spec: Use the middle of the horizontal advance vector as
the X coordinate of the vertical origin.
FreeType's algorithm goes wrong if you have a really small glyph
(like the full-width, circle-like dot at the end of the sentence, as
used in CJK scripts) with large bearings. With the FreeType
algorithm this dot gets centered on the baseline; with the PDF
algorithm it gets the correct location (in the top right). Note
that this is a serious issue, it's like printing the dot at the end
of a Roman sentence at the center of the textline instead of on the
baseline like it should. So i believe the PDF spec's algorithm
should be used in FreeType as well.
The `vertBearingY' value for such small glyphs is also very strange
if no `vmtx' information is present, since the height of the bbox is
not representable for the height of the glyph visually (the
whitespace up to the baseline is part of the glyph). The fix also
includes some code for a better estimate of `vertBearingY'.
* src/base/ftobjs.c (ft_synthesize_vertical_metrics): `vertBearingX'
is now calculated as described by the Adobe PDF Spec. Estimate for
`vertBearingY' now works better for small glyphs completely above or
below the baseline into account.
* src/cff/cffgload.c (cff_slot_load): `vertBearingX' is now
calculated as described by the Adobe PDF Spec. Vertical metrics
information was always ignored when FT_CONFIG_OPTION_OLD_INTERNALS
was not defined.
* src/truetype/ttgload.c (compute_glyph_metrics): `vertBearingX' is
now calculated as described by the Adobe PDF Spec.
Special notes to Unix users
===========================
Please read the file `docs/UPGRADE.UNIX'. It contains important
information regarding the installation of FreeType on Unix systems,
especially GNU based operating systems like GNU/Linux.
FreeType 2's library is called `libfreetype', FreeType 1's library
is called `libttf'. They are *not* compatible!
FreeType 2.3.9
==============
Please read the docs/CHANGES file, it contains IMPORTANT
INFORMATION.
Read the files `docs/INSTALL' for installation instructions.
The FreeType 2 API reference is located in `docs/reference'; use the
file `ft2-doc.html' as the top entry point. Additional
documentation is available as a separate package from our sites. Go
to
http://download.savannah.gnu.org/releases/freetype/
and download one of the following files.
freetype-doc-2.3.9.tar.bz2
freetype-doc-2.3.9.tar.gz
ftdoc239.zip
Bugs
====
Please report bugs by e-mail to `freetype-devel@nongnu.org'. Don't
forget to send a detailed explanation of the problem -- there is
nothing worse than receiving a terse message that only says `it
doesn't work'.
Alternatively, you may submit a bug report at
https://savannah.nongnu.org/bugs/?group=freetype
Enjoy!
The FreeType Team
----------------------------------------------------------------------
Copyright 2006, 2007, 2008, 2009 by
David Turner, Robert Wilhelm, and Werner Lemberg.
This file is part of the FreeType project, and may only be used,
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