Embedded images with Pango and Cairo

The goal: To embed images within text rendered by Pango (similar to how
some chat clients display inline emoticons), using a Cairo backend.

The research: After much Google-grinding I came across the
pango_cairo_context_get_shape_renderer and pango_attr_shape_new
functions in the original C library.

The problem: I am unable to locate bindings for the aforementioned Pango
functions in Ruby-Gnome, and I can’t find an alternative way of
embedding images.

All help is much appreciated.