Window Questions

["Mark A. Tapia" <markt@dgp.toronto.edu>]

osiris@ccwf.cc.utexas.edu writes on Fri Jul  9 14:03:12 1993:
   Try this: make an instance of a window, start a picture in that window, and
   then flip that window from foreground to background a few times.  Now get
   the picture.  You will notice that the picture will vary in size depending
   on the number of times that you obscured and uncovered the window even
   though you never sent a single drawing command to the window.

The same code includes:
    (start-picture wind)
    ... send window to the foreground and background ...
    (setq ppict (get-picture wind))
Answer:
The start-picture command is a highlevel interface to the openPicture
trap call. The generic fuynction hides the en and starts recording quickdraw
commands in a picture whose frame is the portrect of the window wind.
Every time you send the window to the foreground or bring another window into
the foreground the commands will be recorded.

You can see the same "quirky" behaviour if you say
    (start-picture wind)
    (setq n 10)
    (loop for i fixnum from 1 to n
	  do (print i))
    (setq pict (get-picture wind))
    (print wind)
    (kill-picture pict)
Changing the value of n from 10 to 1 will change the "size" of the
picture.

If you want to draw an entire picture, then wrap the forms in 
(without-interrupts  form*)

mark