Rectangle Problem

[Cubist at aol.com]

sez dburgun at dsl.pipex.com:
>Given I have a "BoundingRect" and "UserRect", how can I check that 
>"UserRect" is inside "BoundingRect"? If it overlaps I want to either 
>clip the rectangle or stop it from moving outside of the BoundingRect 
>in the first place.
   Well, a rect is a four-number list, right? If UserRect is wholly contained 
within BoundingRect, the "left" value for UserRect will be equal to, or 
greater than, the "left" value for BoundingRect; similarly, the "down" value for 
UserRect will be less than, or equal to, the "down" value for BoundingRect; and 
so on. Thus, what you want can be done by a function like this:

function ItsInside UserRect, BoundRect
  if item 1 of UserRect => item 1 of BoundRect then return false
  if item 2 of UserRect => item 2 of BoundRect then return false
  if item 3 of UserRect <= item 3 of BoundRect then return false
  if item 4 of UserRect <= item 4 of BoundRect then return false
  return true
end ItsInside

   If you wanted to, you could turn this handler's code into a one-liner by 
combining the four comparisons, like so:

on ItsInside Ru, Rb
  # mind the line-wrap!
  return ((item 1 of Ru => item 1 of Rb) and (item 2 of Ru => item 2 of Rb) 
and (item 3 of Ru <= item 3 of Rb) and (item 4 of Ru <= item 4 of Rb))
end ItsInside

   Hope this helps...