Support for OpenType advance features please! [closed]
There are a lot of OpenType fonts out there which contain not only ligatures but also alternative glyphs, stylistis sets, old style numbers, lining/proportional numbers, true small caps and some even have true petite caps. MS Word supports some of these features but not all (no true small caps, for example). LibreOffice supports none of these OpenType features. Instead, it supports Graphite fonts, of which there is only a handful (unlike the hundreds of OpenType fonts available).
Are there any plans to implement OpenType advance typography feature support in LibreOffice? I think that this is a matter of some importance (and urgency), and it would give LibreOffice quite an advantage over MS Word and other word processors.
I wonder: does the difficulty of supporting OpenType have anything to do with LibreOffice using its own GUI toolkit and thus not being able to easily rely on libraries/frameworks such as Pango/Harfbuzz/Cairo?
Who said it was difficult?
It is probably not the most complex of tasks, but judging by various articles in TUGBoat and other publications in the TeX world, it is a daunting task, because implementing the OpenType specification is complex. If we are to judge by the number of complete OTF implementations (very few!) then I think we can infer that implementing it is complex. Complete implementations I know of: XeTeX and LuaTeX, Adobe CS and other DTP applications, but unfortunately not Scribus.
See this Wikipedia article to get a good overview of the state of OpenType support. Things are getting better, but the situation is still far from ideal. Also, as a daily OS X user, I can confirm that OS X’s OpenType support is not that satisfactory: it is buggy and unreliable.
Even XeTeX isn't complete, as you can see by scrolling almost to the bottom of this page. It is missing Swash, Ornaments, Slashed Zero, Justification Alternates, Alternate Annotation, Mathematical Greek (??), Localized Forms, Glyph (De)Composition, Required Ligatures, Mark Positioning Via Subs, and Isolated Form.
Thanks for pointing this out, I had forgotten about such gory details :-). This article, and the “ilovetypography.com” site in general, is a great resource.
At least it looks like Caolan McNamara has implemented localized forms separately, as shown by oweng in the comments of my answer.
Here's a complete Web implementation of OpenType: http://www.impallari.com/testing/ And its source code: https://github.com/impallari/font-testing-page
This feature is extremely important especially for arabic fonts, as they are based on ligatures, glyphs etc.