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From: Christoph Kukulies <kuku@gilberto.physik.rwth-aachen.de>
Message-Id: <199703260959.KAA13357@gilberto.physik.rwth-aachen.de>
Subject: Re: X11 programming...
In-Reply-To: <19970325201750.16289@gaffaneys.com> from Zach Heilig at "Mar 25, 97 08:17:50 pm"
To: zach@blizzard.gaffaneys.com (Zach Heilig)
Date: Wed, 26 Mar 1997 10:59:24 +0100 (MET)
Cc: questions@freebsd.org
Reply-To: Christoph Kukulies <kuku@gilberto.physik.rwth-aachen.de>
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> I know I should get a book, but I haven't figured out which of the available
> books are good.  Any hints here would be appreciated (cost isn't really a
> very big issue; <= US$500 would be great).
> 
> So, I thought I would see how far I could go just reading the man pages.
> Basically, I am just trying to get a window (white... or actually _any_
> background) up on the screen.  This is as far as I have gotten, but I just
> can't seem to get the window to display.  I don't get any compile errors or
> run-time errors (anymore :-), but still I get nothing.  I wonder what I am
> missing?

You have to wait for the EXPOSE event. The sleep() isn't good for anything
but putting your whole process to sleep ;-)

> 
> /*
>  * xtest.c: testing X functions...
>  */
> 
> #include <stdio.h>
> #include <stdlib.h>
> 
> #include <sysexits.h>
> 
> #include <X11/Xlib.h>
> 
> int
> main(void)
> {
>     Display *disp;
>     Window root;
>     Window mainwin;
>     int scrn;
>     unsigned long black;
>     unsigned long white;
>     char *display;
> 
>     display = getenv("DISPLAY");
>     if (!display)
> 	display = ":0.0";
> 
>     if (!(disp = XOpenDisplay(display))) {
> 	fprintf(stderr, "Error: Could not open the '%s' display.\n", display);
> 	exit(EX_UNAVAILABLE);
>     }
> 
>     scrn = DefaultScreen(disp);
>     root = RootWindow(disp, scrn);
> 
>     white = WhitePixel(disp, scrn);
>     black = BlackPixel(disp, scrn);
> 
>     mainwin = XCreateSimpleWindow(disp, root, 10, 10, 150, 50, 2, white,
> 	white);
>     XMapWindow(disp, mainwin);

      while(1) {
         XEvent          rep;
         XNextEvent(disp , &rep);
         switch(rep.type){
           case EXPOSE:
              XClearWindow(dpy,((XExposeEvent *)&rep)->window);
              break;
          /* case ... process other events here */
           default:
              break;
         }
      }

> 
>     sleep(5);
> 
>     XCloseDisplay(disp);
> 
>     return 0;
> }
> 
> 
> -- 
> Zach Heilig (zach@blizzard.gaffaneys.com) | ALL unsolicited commercial email
> /var/spool/news is 110% full,             | is unwelcome.  I avoid dealing
> please delete all the spam you can.       | with companies that email ads.
> 

--
Christoph P. U. Kukulies kuku@gil.physik.rwth-aachen.de