[STUMP] tree-height and tree-width

[Magnus Henoch]

Look closely at these function definitions in core.lisp:

(defun tree-x (screen tree)
  (tree-accum-fn tree #'min (lambda (n)
                              (let ((f (frame-data screen n)))
                                (frame-x f)))))

(defun tree-y (screen tree)
  (tree-accum-fn tree #'min (lambda (n)
                              (let ((f (frame-data screen n)))
                                (frame-y f)))))

(defun tree-width (screen tree)
  (tree-accum-fn tree #'+ (lambda (n)
                            (let ((f (frame-data screen n)))
                              (frame-width f)))))

(defun tree-height (screen tree)
  (tree-accum-fn tree #'+ (lambda (n)
                            (let ((f (frame-data screen n)))
                              (frame-height f)))))

tree-x and tree-y are correct.  tree-width and tree-height are not.
For example, if you have two frames next to eachother, tree-height
will add their heights and return twice the correct result.

One way to fix this is to add tree-right and tree-bottom, making them
similar to tree-x and tree-y, and define tree-width as (- tree-right
tree-x) and likewise for tree-height.  But this would mean traversing
the tree twice to get width or height.  Can someone see a more elegant
solution?

Magnus