code: public boolean contains(Viewport v) {
          // check for empty first
          return this.left < this.right && this.bottom < this.top
                  // now check for containment
                  && left <= v.left && top >= v.top && right >= v.right && bottom <= v.bottom;
      }
docs: Returns true iff the specified viewport r is inside or equal to this viewport. An empty viewport never contains
  another viewport.
  
  @param v The viewport being tested for containment.
  @return true iff the specified viewport r is inside or equal to this viewport