[mcclim-devel] Redisplay and pixmaps

[Sascha Wilde]

Hi *,

I'm new to CLIM and currently looking for a good (and simple) way to
redisplay a rendered picture (my toy program is an mandelbrot
generator).

My problem is, that the :display-function which in my case simply copies
a pixmap to the application pane is less often called than actual
redisplay is needed.

Given the following simple example code:

--8<---------------cut here---------------start------------->8---
(in-package :common-lisp-user)

(defpackage "APP"
  (:use :clim :clim-lisp)
  (:export "APP-MAIN"))

(in-package :app)

(define-application-frame superapp ()
  ((gfx :initform nil :accessor gfx)
   (redisplay-counter :initform 0 :accessor redisplaynr))
  (:pointer-documentation t)
  (:panes
   (app :application :display-function #'redraw-gfx
   :height 400 :width 600)
   (int :interactor :height 400 :width 600))
  (:layouts
   (default (vertically () app int))))

(define-superapp-command (com-draw :name t) ()
  (setf (gfx *application-frame*)
  (allocate-pixmap (frame-standard-output *application-frame*)
                                           600 400))
  (draw-line* (gfx *application-frame*) 0 0 599 399 :ink +red+))

(defun redraw-gfx (frame pane)
  (if (gfx frame)
      (progn (copy-from-pixmap (gfx frame) 0 0 600 400 pane 10 10)
           (format pane "Redisplay #~a" (incf (redisplaynr frame))))
      (format pane "No pic yet...")))

(defun app-main ()
  (run-frame-top-level (make-application-frame 'superapp)))
--8<---------------cut here---------------end--------------->8---

Run and issue the command "Draw", ok now the pixmap is displayed.  But
when a part of the frame is obscured by another window after getting the
CLIM frame back to front the redisplay function is _not_ called.  (Can
be seen, both, by not refreshing the pixmap and not incrementing the
redisplay-counter).

BUT: The string "Redisplay #1" _is_ redrawn, so some more low level part
of CLIM knows that a redraw is needed and does that for the text send to
the standard output stream.

So two questions:
1. What do I have to do, so that the 
-- 
Sascha Wilde : "Ist es nicht schon schlimm genug, dass ICH hier rumtrolle?"
             : (Henning Leise in d.o.c.)