how to cast cairo::FontFace to some thing pango::Layout can use?

[ogios]

i'm trying to load a custimized font, it's not a file but static &[u8].
it's a small font and only used for numbers.

but i can only manage to load it into cairo::FontFace with freetype but don't know how to use it with pango::Layout:

// load into `cairo::FontFace`
let fc = ft::Library::init()
  .map_err(|e| format!("Init freetype error: {e}"))
  .and_then(|lib| {
    let fontface = lib
      .new_memory_face(Rc::new(raw::RAW_FONT.to_vec()), 0)
      .map_err(|e| format!("Init ft fontface error: {e}"))?;
    FontFace::create_from_ft(&fontface)
       .map_err(|e| format!("Init cairo fontface error: {e}"))
});

[sdroege]

The only way I'm aware of is by making the font available to fontconfig, and then loading it in pango via the font description.

You probably want to ask this at https://discourse.gnome.org as it's more about how to use pango in general.