Retrieve available font weights

[bernaferrari]

I know that Flutter "rounds" your weight selection to the nearest available, but how do you find all the available weights for a font? I couldn't find any method that does this.

For example, if I had a font selector with weight, how would I let the user select semibold/bold/black in one font, but just regular/light in the other? If I display the 9 options and ask to choose one, it would be trial and error.