[Silgraphite-devel] compiler question: white space directionality

[<Sha...@si...>]

One of the things the compiler does is set the directionality for each 
glyph. This is done by first finding the default value based on the 
Unicode properties (via ICU) and then using any values spelled out in the 
GDL. However, there is a line in the compiler that says "Don't bother 
doing this if the font has no Bidi pass."

This isn't quite adequate. Even for a font that isn't right-to-left or 
bidirectional itself, it needs to be able to reorder whitespace at the end 
of a line when it is combined with text of a different script and 
direction. And Graphite wants to use the directionality attribute of the 
space glyphs to do this.

My inclination is to get rid of the test that says, "Don't do this if the 
font has no Bidi pass." That would add a slight bit of time to the 
compiler, but who would notice? Really I think the only difference is that 
maybe you don't want warnings if there is no Bidi pass. But now that we're 
using ICU, it should always be possible to set the default.

If we leave it the way it is, a font developer can still make it work by 
explicitly putting the directionality codes in the GDL. But it's easy to 
forget to do that--like I forgot for our Roman fonts--and it really 
shouldn't be necessary.