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Re: Painting regions then saving them

Kemi Jona (jona@ils.nwu.edu) wrote:
: In part of the application I am working on, I need to allow the user to
: paint arbitrary regions on the screen with a choice of 2 patterns (i.e.
: similar to MacPaint-style operations).  I've got a rudimentary version of
: this working (code is at end of message).

: The part that I can't figure out is how to store what the user has drawn so
: that (a) I can save it between sessions, and (b) I can figure out what
: parts of the screen are painted with which pattern.

: I've tried using _OpenPicture, _OpenRgn & friends and have been able to get
: pict-handles and regions that capture what the user has drawn - but when I
: do that, the drawing doesn't appear on the screen. 

: Thus, a better description of my problem is how does one display quickdraw
: commands *simultaneously* to both the screen and to a picture? 

: Or is there a better way to do this than with _OpenPicture?  Are regions
: the answer?

: Thanks for any pointers,

Hello Kemi,
I do not know wether pictures or regions are the better choice for
you, since I do not specificly know what you want to do.

But the answer on how to get a picture and window drawings, simultanously,
is quite easy.  When you do a (start-picture ...) the cursor automatically
gets hidden.  Just add a (pen-show ...) command to your code and
it works:

; Define a paint-window class

(defclass paint-window (window)
  ((picture :initarg pict :initform nil :accessor picture))

(defvar *current-pattern* *black-pattern*)

; Slightly change the event handler:
(defmethod view-click-event-handler ((win paint-window) where)
  (if (eq (find-view-containing-point win where) win)
    (with-focused-view win
      ; start a picture, the pen gets hidden:
      (start-picture win)
      ; re-record old drawings, if there are:  
      (when (picture win) 
        (draw-picture win (picture win)))
      ; now make the pen visible
      (pen-show win)
      ; your code:
      (let ((penloc where)
            (oldpenloc 0)) 
           (unless (mouse-down-p) (return))
           (unless (= penloc oldpenloc)
             ; slightly changed because 
             ; with-pen-state seems to be not standard MCL
             (set-pen-size win #@(15 15))
             (set-pen-pattern win *current-pattern*)
             (move-to win penloc)
             (#_Lineto (point-h penloc) (point-v penloc)))

           (setq oldpenloc penloc)
           (setq penloc (view-mouse-position win)))))
      ; undo the show pen command from above
      ; because pen shown/hidden is not binary,
      ; rather it counts the number of show and hide commands.

      (pen-hide win)
      ; save the new picture
      (setf (picture win)
            (get-picture win)))

; small test:  make some drawings to window xx
; then coy them to window yy.

(setf xx (make-instance 'paint-window))
(setf yy (make-instance 'paint-window))
(draw-picture yy (picture xx))


|    /                                                       
|   /    ____
|  /    /    \     ....
| /\   /      \   ......
|/  \  |    ) |    ./..
|    \ \      />   /                                         Kai Zimmermann
|     \_\____/  \_/                      zimmerma@informatik.uni-hamburg.de