Emacs, when built with Haiku windowing support, can be built with
several different font backends. You can specify font backends by
specifying -xrm Emacs.fontBackend:BACKEND on the command line
used to invoke Emacs, where BACKEND is one of the backends
specified below, or on a per-frame basis by changing the
font-backend frame parameter.
Two of these backends, ftcr and ftcrhb are identical
to their counterparts on the X Window System. There is also a
Haiku-specific backend named haiku, that uses the App Server to
draw fonts, but does not at present support display of color font and
emoji.