[ltp] switch between clone mode and second screen

[Alex Deucher]

On Thu, 10 Feb 2005 09:27:55 +0100, Ulrich Kuehn <ukuehn@acm.org> wrote:
> On Wed, 2005-02-09 at 14:34 -0500, Alex Deucher wrote:
> > On Wed, 09 Feb 2005 20:30:06 +0100, Ulrich Kuehn <ukuehn@acm.org> wrote:
> > > Hi,
> > >
> > > I am just wondering if there is a way to switch the external DAC output
> > > between clone mode and a second, independent screen.
> > >
> > > My reasoning is as follows: I have a 17" monitor with 1280x1024
> > > resolution which I would like to use in addition to the internal
> > > display. Using the ServerLayout section in XF86Config works fine here.
> > >
> > > But for giving presentations on a typical beamer, the resolution is just
> > > too high, usual is 1024x768; furthermore I like to see what's beamed to
> > > the wall. So the clone mode is the method of choice here.
> > >
> > > Is there a tool that allows to switch between both modes without
> > > restarting X? I am aware that only the internal display would probably
> > > be cloned, not the external.
> > >
> > > Can someone give me hint with this issue?
> >
> > If you are using a radeon, take a look at MergedFB.  It should do what you want.
> 
> Thanks for the hint. Telling from the documentation, this will result in
> my laptops internal screen be only a viewport (1024x768) into a larger
> virtual screen (1024x1024), scrolling around. I consider this a rather
> serious show-stopper. I expect also problems with having full-screen
> presentations.

you can user xrandr with mergedfb to actually change between metamodes
and the desktop will resize accordingly.  you will only get the
scrolling effect if you are using different size modes on each crtc in
either dualhead or clone mode.

Alex

> 
> I was in fact more looking into a setup like dual-head, having two
> framebuffers (especially regarding memory layout), but the ability to
> switch the external DAC between showing the second FB (dual-head) and
> showing the internal FB (clone), also switching resolution.
> 
> Ulrich