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From: marbru@auto-trol.com (Martin Brunecky)
Newsgroups: comp.windows.x.motif
Subject: Re: writing Widgets with Float resources
Message-ID: <1991May31.180954.23462@auto-trol.com>
Date: 31 May 91 18:09:54 GMT
References: <13743@dog.ee.lbl.gov>
Sender: news@auto-trol.com
Organization: Auto-trol Technology Corporation
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In article <13743@dog.ee.lbl.gov> anderson@rubato.lbl.gov () writes:
>
>I have started to write a few Motif widgets (subclassing Primitive,
>for instance), and have things working fine as long as various
>resources are "ints" (XmRInt type resources).  But I need them
>to be "floats"  (XmRFloat types).
>
>It appears that no matter what I try, XtSetValues passes junk
>as the float;  as soon as I get into my SetValues function and
>take a look at what is passed, I get some bizarre value. 

  We do use WsRFloat resources (as well as WsRDouble, but those are
  passed by reference).
  Your problem is not that mysterious.
  It is the "C" compiler which typecasts the "value", and for the
  conversion from float it does what you see.

  The way we do SetValues on WsRFloat resources is ....

  typedef union u
   {
   long int   int;
   float      float;
   }

  u value;
  value.float = desired float value
  XtSerArg ( arg[n], WsNangle, value.int );

  This way, the typecast in SetArg does no damage, and we get our floats
  delivered right.

-- 
=*= Opinions presented here are solely of my own and not those of Auto-trol =*=
Martin Brunecky                      marbru%auto-trol@sunpeaks.central.sun.com
(303) 252-2499                       (better avoid:  marbru@auto-trol.COM )
Auto-trol Technology Corp. 12500 North Washington St., Denver, CO 80241-2404