Detect width at specific y value

[thekillerbigmac]

The title is basically what I am trying to do.

I have a MovieClip that has a bunch of MovieClips inside it. I am trying to figure out how wide the MC is at a specific y value. Not sure if there is an easy way to do this.

For an example.

OOOOOOOO
O      O
O      O
OOOOOOOOOOOO
  O        O
  O        O
  OOOOOOOOOO

This is the shape of the MC. It is not solid all the way through, it has MCs strewn about inside this outline. I am trying to figure out how wide it is from, say the second 'O' from the bottom. Left to right. The actual MC.width would be 12 'O's wide. But at that bottom portion, it would be 10 'O's wide. I'm not sure how I can do this.

Anyone have an idea to throw out there?

Thanks,
~Bill L.