[comp.windows.x] problem with backing store and XDrawImageString of the ps2

TRANLE@INTELLICORP.COM (Minh Tran-Le) (02/23/90)

I am running on a PS2 AIX with the X11R4 and I have found the following
problem:

if you have an unmapped window with the backing store set to Always
and you try to write to it, the server will write directly the top
left corner of your screen instead of doing it to the backing pixmap.

Does anybody have a fix for that problem or knows where is the code for doing
the lowlevel DrawImageString for the ps2 8514 display ? Is it hidden in the
ibm8514.o file that was distributed ?

Here is the small lisp code to reproduce it in clx:

;; -----
(setq *display* (xlib:open-display "your-host"))
(setq *root* (xlib:screen-root (xlib:display-default-screen *display*)))

;; create a window but do not map it
(setq *w* (xlib:create-window :parent *root*
			      :x 10 :y 10 :width 100 :height 100 :depth 8
			      :backing-store :always
			      :background 0))

(setq *gc* (xlib:create-gcontext :drawable *w*
			         :foreground 1 :background 0))

;; write a character "a" at (20, 20) which write the character directly
;; to your screen.
(xlib:draw-image-glyph *w* *gc* 20 20 (char-code #\a))

(xlib:display-force-output *display*)
;; -----


Thanks, Tran-Le.

arpanet: tranle@intellicorp.com
uucp:    ..sun!icmv!mtranle
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