[ltp] switch between clone mode and second screen

[Ulrich Kuehn]

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.

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