Switching between virtual desktops

[McDonald, Michael-p7438c]

________________________________

	From: xorg-bounces at lists.freedesktop.org
[mailto:xorg-bounces at lists.freedesktop.org] On Behalf Of Luca Bezerra
	Sent: Tuesday, June 02, 2009 11:20 AM
	To: Luca Bezerra; xorg at lists.freedesktop.org
	Subject: Re: Switching between virtual desktops
	
	

	So it'd only switch the output after it has switched a virtual
desktop, making sure one wouldn't switch without the other.
	 

If you wait to switch monitors until after the virtual desktop has been
switched, the the new virtual desktop will be displayed on the old
monitor! You have to do do something more like this:
 
while (1) {
    tell video demux to ignore new input
    switch virtual desktops
    tell video demux to output to new monitor
    sleep
}

	 
	 A: Dont worry, I know this isnt far from impossible, I also
have doubts myself. The thing is, my boss has assigned me to this
project, and so far, I've given him no concrete results, since every
approach I've tried was a dead end. 
	As I've mentioned on an email to someone else (again, Im
terrible with names), Im pretty sure second hand hardware isnt really
affordable for this project, since we're inside a federal university, so
every expense in here has to be documented first, then approved by
several departments before the real money is released for the buying.
I'm pretty sure there'll be no approvals for 2nd hand pieces...
21323213213, Im also in favor of using the existing multiterminal (with
multiple graphics boards) solution. Too bad its not up to me to decide
:P
	 

Uh, one of the most fundamental skills an engineer needs to learn, and
learn early, is how to tell his managers their latest "solution" won't
work. It's easier to get away with telling them that if you do have a
working solution. Therefore, let's make this whole problem rest on the
HW guys shoulders:
 
Tell him that his hardware needs to capture the video signal into one of
six separate frame buffers. Your parallel port interface will tell him
which one or none. His hardware will then provide a continuous video
signal out to each of the six monitors connected to it. Users get nice
stable video, you get easy SW task, and boss gets to prove he's a wiz HW
designer.
 
Now, having said all of that, I'd have questioned the whole approach
from the beginning:
 
Where are the monitors coming from? If you're buying them, then there is
money to buy cheap, modern PCs to run each station. If the monitors are
surplus, then check with you university's surplus property department
about getting ahold of discarded computers.
 
Why do users have to log in if all they are going to do is use a single
PDF reader? I assume the student don't have to log in before the can
read a book off the shelves. Instead of using virtual desktops, have
your app map/unmap the N copies of acroread/xpdf/... in sync with you
parallel port output. There's no reason to have a window manager or
virtual desktops at all.
 
BTW, what are you doing about input? How are you planning on handling N
keyboards and N mice?
 
Mike McDonald
 
 
 
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