Glyph Repositioning

[<nsperinck sympatico ca>]

Hi,

I am trying to reposition glyphs through Uniscribe. http://www.codeguru.com/forum/showthread.php?s=&threadid=284771 shows a diagram of what I am trying to achieve. The reason is also explained below. 

Uniscribe’s ScriptTextOut function has a GOFFSET Structure (.du and .dv), apparently an ‘x,y Glyph offset’. In testing on both TrueType and OpenType fonts (Arial, Microsoft Sans Serif) this does not appear to modify the glyph position.

Q. Does anyone know how the GOFFSET feature works and whether it can offset vowel symbols?

There appears to be another helper technology associated with Uniscribe, Microsoft’s OpenType Layout Services (OTLS) which allows Glyph repositioning and substitution through access to the font’s GPOS and GSUB tables. However, the link http://www.microsoft.com/typography/developers/otls/ to OpenType Layout Service Library and Contact details no longer appear supported. 

Q. Does anyone know how to obtain the OpenType Layout Service Library (OTLS)?

Q. Any other suggestions?


Why reposition glyphs?
I am trying to build a prototype for learning to read Arabic with the vowel symbols.

Arabic is difficult to learn to read. It is written from right-to-left and the letters can take as many as four forms. In addition, unlike European languages, beginners learning Arabic have to master reading letters and their accent symbol, representing vowels, stacked vertically two or three high. This combination of the letter and the associated vowel effectively form one syllable. 

When Arabic text is displayed in Windows, the vowel and similar symbols are positioned to the end of the letter and not at identical heights. To make reading easier, I am trying to reposition these vowel symbols (glyph repositioning) so that these vowel symbols occur above or below the centre of the letter and at an equal height as illustrated in the example.

Many thanks for any advice.