IMHO, `FT_Get_Char_Index' is sufficient. For displaying single
characters in `ftinspect' (or a bunch of them once in a separate
window for ftview-like stuff) you don't need a cache for speeding up
things.
Let me know if I'm wrong but isn't it looks up the glyph index corresponding to
the given char code in the char map but we are supposed to print all glyphs instead
of getting a glyph index corresponding to a particular char code. Also, for getting the char code
we would need glyph index. This function is perfect for rendering text string since we can look up
for a particular character's glyph index but not sure how it would be used for getting all glyphs.