Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!wuarchive!uunet!mcsun!hp4nl!phcisa!phcisa.uucp!frans
From: frans@origin.nl
Newsgroups: comp.windows.x
Subject: Re: How can I get the display resolution?
Message-ID: <1362@phcisa.UUCP>
Date: 25 Mar 91 13:47:38 GMT
References: <9103250507.AA07479@lightning.McRCIM.McGill.EDU>
Sender: frans@phcisa.UUCP
Reply-To: frans@phcisa.uucp ()
Organization: ORIGIN/Middleware,Eindhoven,The Netherlands
Lines: 20
In-reply-to: mouse@lightning.mcrcim.mcgill.EDU's message of 25 Mar 91 05:07:17 GMT


The solution you propose is a bit of turning the problem around. The
HeightMMOfScreen(screen) call references the screen resolution as defined 
within the X server. At least in the Sun Server implementation, this is
is a hard-coded constant ( I believe somewhere in server/ddx/mfb/??? ),
defined to be 90 (pixels per inch).

If you want to have the HeightMMOfScreen(screen) call to return the
right value, you have to start the X process with the right argument
( -dpi 83 e.g.) so that the default value gets overruled.

(You can check this behaviour very easily: if you run xdpyinfo in a
high or low resolution display, the resolution reported remains the same,
but the size of the screen reported changes !

Best greetings,

Francois Staes
Origin/Middleware
Eindhoven, The Netherlands.