Re: Status of latin OpenType support in Gnome

[Greg Aumann <Greg_Aumann sil org>]

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Ralph Aichinger wrote:
| Hello!
|
| I am playing around with various font formats lately (on Gnome
| as well as on Windows) and I am wondering if the current
| state of OpenType support for european languages is documented
| somewhere.
|
There are some bug reports in various places. Not much else I think.

| Some programs seem to have some support for .otf flavoured fonts
| (e.g. gedit), some don't (AbiWord, OpenOffice).
|
You need to consider both the application and the text renderer and its
shaping engines to figure out the answer. Applications on Windows
generally use uniscribe. This definitely includes Abiword, Openoffice
and of course Word (and Notepad). On Linux there are several different
text renderers: Pango, icu, and one in Qt. I believe openoffice on Linux
uses icu. Gnome apps will use pango and kde apps Qt.

Also it is fairly common for word processors to bypass the text renderer
for certain codepoint ranges as a performance hack. Openoffice does this
for some codepoint ranges (not sure about latin). Word also does this
for latin except for Word 2003. Abiword 2.2 does not (don't know about
previous versions). I think the justification for this is that there are
precomposed characters available for most languages that use latin
scripts. A glaring exception to this assumption (at least from my
linguist's point of view) is IPA, which makes heavy use of diacritics
and also some ligatures.

So you should test your text renderer and your application seperately
and you should use fonts with known good opentype types (there are a lot
that do not have them for latin).

On Windows you can test a specific version of usp10.dll by making a new
folder and copying the notepad.exe and the usp10.dll you want to test
into that folder. Then run the notepad.exe in that folder. Then it will
use the usp10.dll from that folder in preference to the system version.
You can also do the same thing with openoffice and abiword on windows.
Put the usp10.dll in the same directory as the exe file.

On Linux you should also test renderers using simple text editors, e.g.
gedit, kwrite.

Note the Qt renderer (only tested 3.2.3) doesn't use opentype tables for
latin. Rather it guesses about diacritic placement. It guesses pretty
well though and is able to stack multiple diacritics. Problems are:
doesn't remove dots from i or j with diacritics above, doesn't handle
ligatures, always centres diacritics (which is not always correct e.g.
over j).

The Doulos SIL font has very good opentype support for latin codepoints.
It is freeware and downloadable from
http://scripts.sil.org/cms/scripts/page.php?site_id=nrsi&item_id=DoulosSILfont
Code2000 is another good font to try http://home.att.net/~jameskass/
If you file bug reports it is a good idea to try several fonts from
different sources as so that they know it is not a problem with a
specific font. Also include screenshots.

I strongly suggest looking at the following bug reports:
http://bugzilla.gnome.org/show_bug.cgi?id=101079
http://www.openoffice.org/issues/show_bug.cgi?id=37073
http://bugzilla.abisource.com/show_bug.cgi?id=8225

at the moment I can't get to bugzilla.abisource.org to check if the
above link is correct. But there is definitely a relevant bug report there.

Abiword 2.2.3 (not released yet but a snapshot build is available)
incorporates the fix to the bug with Latin diacritics.

| Is it reaonable to file bugs with programs not able to use
| .otf (or TrueType-flavoured OT) fonts?
|
Absolutely. Some people are but not enough as fixing of these bugs is
not a high priority for most projects. Please add stuff to existing bug
reports or file new ones if there isn't a suitable existing report.

| Is it planned to support the more "fancy" OT features,
| �a InDesign, like ligatures for latin alphabets, small caps,
| oldstyle figures or stuff like linking glyphs in script fonts
| like in the new version of zapfino?
|
Abiword and openoffice on windows already support ligatures if the font
supports them.

hope this is helpful
Greg Aumann
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