Add support for the STAT table.

[inferiorhumanorgans]

https://learn.microsoft.com/en-us/typography/opentype/spec/stat

This PR adds support for parsing the STAT table and its related data types. It's a pretty simple table but as in #87 the issues of testing and API design deserve some consideration.

Additionally, should this be placed behind a feature?

[RazrFalcon]

Thanks! Looks pretty good to me.

[yisibl]

It looks like we can update the table in the readme.
https://github.com/RazrFalcon/ttf-parser?tab=readme-ov-file#alternatives

[RazrFalcon]

@yisibl good call!

[RazrFalcon]

Ok, 1.51 compatibility is broken, but we're good otherwise.

[inferiorhumanorgans]

Ok – I've rolled up a few other minor changes. I've also set up a few functions to abstract over getting the value and flags. If that seems in scope for this PR I can push those as well.

[RazrFalcon]

If that seems in scope for this PR I can push those as well.

Sure, let's take a look.

[inferiorhumanorgans]

I'm not sure how far down the rabbit hole it's worth going with providing a higher level API. What I've exposed so far should be useful for both dynamic (e.g. name_id) and non-dynamic (e.g. contains) fonts.

For instance:

fn is_stat_italic() -> bool {
  if let Some(stat) = face.tables().stat {
    if let Some(subtable) = stat.subtable_for_axis(Tag::from_bytes(b"ital"), None) {
      if subtable.contains(Fixed(1.0)) {
        return true;
      }
    }
  }

  return false
}

fn is_bold() -> bool {
  if let Some(stat) = face.tables().stat {
    if let Some(subtable) = stat.subtable_for_axis(Tag::from_bytes(b"wght"), None) {
      if let Some(value) = subtable.value() {
        let named_weight = Weight::from(value.0 as u16);
        if named_weight == Weight::Bold {
          return true;
        }
      }
    }
  }

  return false
}

[RazrFalcon]

If you think it's good enough I'm fine with merging it.

[inferiorhumanorgans]

Works for me.