Path: utzoo!attcan!uunet!lll-winken!lll-ncis!helios.ee.lbl.gov!pasteur!ames!husc6!bloom-beacon!primerd!zaphod!doug
From: doug@zaphod.prime.com
Newsgroups: comp.windows.x
Subject: CLX and inverting pixels
Message-ID: <34700004@zaphod>
Date: 5 Jan 89 16:26:00 GMT
Lines: 25
Nf-ID: #N:zaphod:34700004:000:1060
Nf-From: zaphod.prime.com!doug    Jan  5 11:26:00 1989


This is really a question about CLX and not Xlib.  In CLX I cannot find 
a way to operate on a section of pixmap without uploading the bits,
operating on them and then downloading the bits:

(defmethod invert-area ((self drawable) x y width height &aux image-bits image)
  (setq image (get-image self :x x :y y :height height :width width))
  (setq image-bits (xlib::image-x-data image))
  (dotimes (i (length image-bits))
	   (setf (svref image-bits i) (logxor #xFF (svref image-bits i))))
  (put-image self *gc* image :x x :y y))

Now this is clearly a braindamaged way to do this kind of thing which is
pervasively needed to implement popup-menus, buttons,  highlighting text,
etc.  Is there a better way?  Does CLX provide it?  Can an extension to
CLX be easily done which handles this?  

Douglas Rand
 
  Internet:  doug@zaphod.prime.com
  Usenet:    primerd!zaphod!doug 
  Phone:     (508) - 879 - 2960
  Mail:      Prime Computer, 500 Old Conn Path, MS10C-17, Framingham, Ma 01701

->  The above opinions are mine alone.  (well maybe *someone* agrees)