[HarfBuzz] hb-view

[Behdad Esfahbod]

Hi Adam,

On 03/30/11 11:57, Adam Twardoch (List) wrote:
> Behdad,
> 
> it would be tremendously helpful for OpenType testing if you add
> arbitrary feature support for hb-view.

I can't agree more.  What has slowed me down is that I want to allow turning
features on/off on only parts of the string too.

What I probably do is add a --features as you propose, and later on add an XML
markup alternative to do more advanced stuff (probably like pango-view's
--markup).

> You can use the XeTeX notation for commandline parameters (that Jonathan
> developed):
> 
> OpenType font features are chosen with standard tags. They may be either
> comma- or semicolon-separated, and prepended with a + to turn them on
> and a - to turn them off.
> 
> So it could be:
> 
> --features="+smcp,+dlig,-liga"

Works for me.  I'd separate on comma and semicolon, and support all of:

  --features="scmp,+dlig,-liga,kern=0,aalt=2"

In general, turning off is =0, turning on is =1.  Default action (no +, no -,
no =) is to turn on.


> I think there may be (in XeTeX) a syntax for explicitly selecting an nth
> variant for GSUB one-to-one-out-of-many replacements (e.g. "+salt" would
> activate the first variant, and "+salt:2" could activate the second
> etc.). But even just plain enabling/disabling as I described above would
> be very important.

I'd rather use =, not colon.

I'll do this today :).

behdad

> Best,
> Adam