[lug] Re: Another question on X. displaying at two resolutions simultaneously?

[Ed Hill]

On Tue, 2002-12-31 at 10:08, Michael J. Hammel wrote:
> On Tue, 2002-12-31 at 10:10, Phil Rasch wrote:
> > I looked at xinerama, but it looked like it was designed to work with
> > two cards, and they expect to make the displays contain different
> > images (even if it was one logical screen). I want the same image on
> > both displays (just at different resolution)
> 
> Xinerama is actually designed to allow multiple monitors on one or more
> video cards.  It's what is being used to run those "walls of monitors"
> showing one big image.  
> 
> What you need in hardware is video support for dual heads - two
> monitors, one video chipset (re: card).  If you're laptop (which is, if
> I remember the earlier messages, what you're trying this on) doesn't
> support this, you won't be able to do it.
> 
> I know on my IBM i1410 (and older laptop) I could use keyboard controls
> to make the display go to the laptop display and out the VGA port at the
> same time.  I used this method for doing my talks at ALS and
> LinuxWorld.  I'm pretty sure you need to do some tweaking to the XFree86
> config file to make it work under X, but I don't remember it being too
> difficult.  Problem is, I don't think I still have that config.  I've
> reloaded the OS since then and I don't think I kept the old config. 
> That was pre-XFree86 4.x too, so maybe such tweaks are no longer
> necessary.


<disclaimer> I'm no XFree86 expert. </disclaimer>

I believe Mr. Hammel is on target.

Flipping through "Fn-F7", my ThinkPad A22p running XFree 4.x will
simultaneously display the same desktop image on both the LCD at
1600x1200 and on a projector at 1024x768.  Of course, it looks a lot
nicer at the higher res, but the text is visible at the lower res using
a sufficiently large font.  I've given a few presentations using it in
exactly this manner.

I've also had problems with some projectors.  Apparently, not all
projectors will sync to the signal.  I have no idea why most work and a
few won't.  Perhaps its an XFree modeline config thing.  Luckily, most
projectors that I've used (including all the projectors in this
department) work fine with my config.

Ed


-- 
Edward H. Hill III, PhD 
Post-Doctoral Researcher   |  Email:  ed at eh3.com,  ehill at mines.edu
Division of ESE            |  URLs:   http://www.eh3.com
Colorado School of Mines   |    http://cesep.mines.edu/people/hill.htm
Golden, CO  80401          |  Phones:  303-384-2094, 303-273-3483
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