I am trying to draw a rectangle inside a window using Common Lisp X Interface:
(asdf:load-system "clx")
(in-package :xlib)
(defun main ()
(let* ((display (open-default-display))
(screen (display-default-screen display))
(colormap (screen-default-colormap screen))
(font (open-font display "fixed")))
(let* ((window (create-window
:parent (screen-root screen)
:x 0
:y 0
:width 512
:height 512
:border (screen-black-pixel screen)
:border-width 2
:bit-gravity :center
:colormap colormap
:background (alloc-color colormap
(lookup-color colormap
"white"))))
(foreground (create-gcontext
:drawable window
:fill-style :solid
:background (screen-white-pixel screen)
:foreground (alloc-color colormap
(lookup-color
colormap
"red"))
:font font)))
(map-window window)
(unwind-protect
(progn
(draw-rectangle window foreground 0 0 100 100 :fill-p) ;; no effect
(display-force-output display)
(display-finish-output display)
(sleep 2))
(CLOSE-DISPLAY display)))))
What I get is just an empty window. Could you please tell me what I am doing wrong. Thanks.
Interesting. After playing with your code a considerable time, I made it work within a loop. It seems like clx wants you to perform the drawing at least once? Here, it works if you replace your progn with a loop for example:
...
(unwind-protect
(loop repeat 3
do
(draw-rectangle window foreground 0 0 100 100 :fill-p) ;; no effect
(display-force-output display)
;;(display-finish-output display)
(sleep 1))
(CLOSE-DISPLAY display)))))