Path: utzoo!attcan!uunet!cs.utexas.edu!tut.cis.ohio-state.edu!bloom-beacon!sae.UUCP!mikeo
From: mikeo@sae.UUCP (Mike Ovington Overhead)
Newsgroups: comp.windows.x
Subject: Drawing lines in windows with bitmaps
Message-ID: <8905022004.AA09962@sae.com>
Date: 2 May 89 20:04:34 GMT
Sender: daemon@bloom-beacon.MIT.EDU
Organization: The Internet
Lines: 26


      I have a window which has a map background set by
   XSetWindowBackgroundPixmap. I then draw lines and symbols --
   which represent nodes and connections in a network -- on top
   of the map background.
      As the status of the connections changes, or as routes
   change, I would like to update the window by "erasing" some
   old lines and drawing new ones. I am currently erasing
   lines by redrawing them in the window's background color.
   This gets rid of the lines, but corrupts the background map.
   I can't draw the lines with GXxor, since, on color machines,
   the lines are color coded.
      As a workaround, I am clearing the window anytime I have
   to actually move lines. The clear operation redraws the 
   map background, and the exposure handler and redraw list
   draws the correct lines, but this causes the whole screen
   to blink at the user.
      Does anyone have a better idea of how to "erase" a object
   drawn in a window that has a background pixmap?


   Michael S. Ovington				uunet!sundc!sae!mikeo
   Software Architecture & Engineering
   1600 Wilson Boulavard, Suite 500
   Arlington, VA 22209
   (703) 276-7910