dw:redisplay-helper-stream

[York@Chuck-Jones.West.Dialnet.ILA.COM (William M. York)]

    Date: Thu, 3 Oct 1991 22:45:43 PDT
    From: shirley@parc.xerox.com (Mark Shirley)


	I'm trying to write something similar to dw:format-graph-from-root but
    with a different layout algorithm.  The key element I need is a way to figure
    out the bounding box for some text and graphical output before actually
    writing those things to the output stream.  For instance, I need a "helper"
    stream that produces no output, but records the motions of the cursor and the
    bounding boxes of graphics calls.

Have you found CONTINUATION-OUTPUT-SIZE?  It is a utility that
will return the size parameters (width, height, x-motion,
y-motion, min-x-position, min-y-position) of the output produced
by a given function.

  (dw:continuation-output-size
    #'(lambda (stream) (write-string "foo
  bar" stream))
    *standard-output*)

=>
      
  24
  28
  24
  28
  0
  NIL