Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!leah!rpi!rpi.edu!hiebeler
From: hiebeler@turing.cs.rpi.edu (Dave Hiebeler)
Newsgroups: comp.windows.x
Subject: backing_store
Message-ID: <HIEBELER.89Apr12174749@turing.cs.rpi.edu>
Date: 12 Apr 89 21:47:49 GMT
Sender: usenet@rpi.edu
Distribution: na
Organization: RPI CS Dept
Lines: 39


  Has anyone had any experience with backing_store under X11R3
on Suns?
  I tried to enable it (on a Sun 3/50 running X11R3) as follows:

    XSetWindowAttributes attributes[1];
    Display *display;
    Widget control_rootwidget, draw_rootwidget;
    
    control_rootwidget = XtInitialize(argv[0],"Xmessenger",NULL,0,&argc,argv);
    display = XtDisplay(control_rootwidget);
    draw_rootwidget = XtCreateApplicationShell("Xmessenger.draw",
						  topLevelShellWidgetClass,
						  NULL,0);
    init_draw_box();  /* this puts a viewport inside the draw_rootwidget */
    
    XtRealizeWidget(control_rootwidget);
    XtRealizeWidget(draw_rootwidget);
    
    attributes[0].backing_store = Always; /* also tried WhenMapped */
    XChangeWindowAttributes(display,XtWindow(draw_rootwidget),
			    CWBackingStore,attributes);

  But it seemed to have no effect.  I'm putting a viewport under
the draw_rootwidget, with a box in the viewport. I then use
xlib routines to draw in that box.  The reason I want backing-store
is because if I scroll part of the image off-screen, when I
scroll it back, it does not get redisplayed.
  My current solution for this is that I have a redraw() routine
which I call whenever I detect an expose event; but redrawing
takes much too long, as I draw a large number of lines in the box.

  Any suggestions would be appreciated.

--
Dave Hiebeler             Internet: hiebeler@cs.rpi.edu  (preferred address)
Computer Science Dept.              hiebeler@itsgw.rpi.edu
Amos Eaton Bldg.            Bitnet: userfrzk@rpitsmts.bitnet
Rensselaer Polytechnic Institute / Troy, NY 12180-3590