+#ifdef USE_FONT_BACKEND
+void
+x_set_font_backend (f, new_value, old_value)
+ struct frame *f;
+ Lisp_Object new_value, old_value;
+{
+ if (! NILP (new_value)
+ && !CONSP (new_value))
+ {
+ char *p0, *p1;
+
+ CHECK_STRING (new_value);
+ p0 = p1 = SDATA (new_value);
+ new_value = Qnil;
+ while (*p0)
+ {
+ while (*p1 && *p1 != ',') p1++;
+ if (p0 < p1)
+ new_value = Fcons (Fintern (make_string (p0, p1 - p0), Qnil),
+ new_value);
+ if (*p1)
+ p1++;
+ p0 = p1;
+ }
+ new_value = Fnreverse (new_value);
+ }
+
+ if (! NILP (old_value) && ! NILP (Fequal (old_value, new_value)))
+ return;
+
+ if (FRAME_FONT_OBJECT (f))
+ free_all_realized_faces (Qnil);
+
+ new_value = font_update_drivers (f, NILP (new_value) ? Qt : new_value);
+ if (NILP (new_value))
+ {
+ if (NILP (old_value))
+ error ("No font backend available");
+ font_update_drivers (f, old_value);
+ error ("None of specified font backends are available");
+ }
+ store_frame_param (f, Qfont_backend, new_value);
+
+ if (FRAME_FONT_OBJECT (f))
+ {
+ Lisp_Object frame;
+
+ XSETFRAME (frame, f);
+ x_set_font (f, Fframe_parameter (frame, Qfont), Qnil);
+ ++face_change_count;
+ ++windows_or_buffers_changed;
+ }
+}
+#endif /* USE_FONT_BACKEND */
+
+