Get Number (& Sizes) of Bitmap-Fonts inside a .ttf

[CyberWorker]

Hi Guys,
I need to find out, how to access the amount of embedded bitmap-sizes inside a .ttf-font(Truetype).

So, if my font has Pointsizes 8,10 and 12 embedded as Bitmaps (which will then rather be used for rendering at these specific sizes), I would need to get a return of '3'.
Additionally I need to know the sizes then, too.

Any ideas on this?