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From: convex!expo.lcs.mit.edu!kit (Chris D. Peterson)
Message-Id: <9005311731.AA17900@expo.lcs.mit.edu>
To: JONES@wharton.upenn.edu
Cc: xpert@expo.lcs.mit.edu, kit@expo.lcs.mit.edu
Subject: Re: XCreateGC vs XtGetGC 
In-Reply-To: Your message of 25 May 90 15:17:33 GMT.
             <25261@netnews.upenn.edu> 
Date: Thu, 31 May 90 13:31:50 -0400


> Originally I put it in the Initialize method for the widget, but it choked
> because the widget was not yet realized.  XtGetGC worked just fine (at least 
> the GC was created).  
> I suspect that I should call XCreateGC in the Realize\
> method for the widget, but wanted to know if that was correct.

Putting the CreateGC call in the initialize procedure it probabally the best
solution.  It solves few other problems too, such as saving server resources for
unrealized widget, and saving round trips when performing an XtSetValues on the
color of an unrealized widget.  If I were writing a widget I would try to put
all my Server resource creation code into Realize.  If you do this, remember
that you will have to make a few XtIsRealized() checks in SetValues() and other
places since the GC may not exist yet.

If you really want to create your GC's at Initialization time then you can just
use the RootWindow of the widget's screen when creating your GC.  The only
reason for the window (well, drawable actually) argument to XtCreateGC is so
that the depth of your GC will match the depth of the GC you are operating on.

BTW:  Don't forget to add a destroy proc to your widget so that the GC is freed
      when the widget is destroyed.


						Chris D. Peterson     
						MIT X Consortium 

Net:	 kit@expo.lcs.mit.edu
Phone:   (617) 253 - 9608	
Address: MIT - Room NE43-213