Re: Progress update on adjustment database

[Craig White]

I discovered there was an issue when I tried using a test font I created with the following as one of its lookups (in ttx format):

<Lookup index="1">
        <LookupType value="1"/>
        <LookupFlag value="0"/>
        <!-- SubTableCount=1 -->
        <SingleSubst index="0">
          <Substitution in="j" out="i"/>
          <Substitution in="zero" out="one"/>
        </SingleSubst>
      </Lookup>

There is one lookup here, but 2 substitutions.  My program needs to iterate through each substitution individually, but the function hb_ot_layout_lookup_collect_glyphs only returns 2 unordered sets representing all the input and output characters for this lookup.  How can I get one substitution at a time?

On Tue, Aug 29, 2023 at 3:13 PM Werner LEMBERG <wl@gnu.org> wrote:

> As I was testing my attempt at supporting GSUB lookups, I found that
> hb_ot_layout_lookup_collect_glyphs, is actually not what I need,
> because I assumed that each lookup contains exactly one
> substitution, when it actually may contain multiple.  What I really
> need is a way to get each individual substitution.  How do I do
> this?

It's not completely clear to me what you exactly need, please give an
example.

Behdad, any idea whether HarfBuzz can help here?  Otherwise it is
probably necessary to parse the GSUB table by ourselves, which is
something I would like to avoid...


    Werner