4. Operating
Barco – TransForm A - X Terminal – DOC-3265-2 – user's manual – Revision 09 – September-2006
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4-2
4.1
Multi-screen capability
An essential feature of T
RANS
F
ORM
A is the
multi-screen
capability, which differs in some points from the multi-
head mode of a conventional X server.
The X server of T
RANS
F
ORM
A allows a root window that extends over all connected projection modules. In this
case, X clients use the whole display area, without even knowing this (
transparent multi-screen
).
For an exact description of the differences between multi-screen and multi-head mode, the terms
display
and
screen
of X.11 terminology are important:
Display
A display contains all input and output devices, which are assigned to an X server. Two or more displays may be
installed on a single computer. In this case several X servers are running each of which has its own keyboard
(mouse, tablet etc.) and its own screen; however, both servers operate logically independent from each other so
that two separate workplaces are available.
Screen
A screen is a logic output device of an X server which is represented generally by a physical output device. An
X server can quite operate several screens. However, such a construction has only one keyboard and one mouse.
It is a workplace for a single person.
The difference between a conventional X server in multi-head mode with several monitors and the multi screen-
capable T
RANS
F
ORM
A controlling a display wall is described below.
Multi head
Every screen is represented in the multi-head mode by a corresponding monitor and has its own root window.
An X client, which is connected to this server can open windows on both screens. However, an individual window
is always completely attached to a screen. Moreover, the client must be specifically programmed for the use of
several screens, what is hardly the case among standard X.11 applications. In addition, when starting such clients
the output screen must be indicated immediately. Finally there are only few window managers, which allow
consistent management over several screens.
Multi screen
In multi-screen mode T
RANS
F
ORM
A offers – in the sense of X.11 – only a single root window, which extends over
the whole display wall with an unlimited number of projection modules. Every window manager allows to posi-
tion the windows of any client somewhere on the display wall, to displace them to another projection module or
even to expand them over several or all projection modules simultaneously.
Multiple logical screens
With the multiple logical screens mode T
RANS
F
ORM
A combines in a way the multi-head mode and the multi-
screen mode. It allows one X server to display multiple screens each on an individual rectangular array of m×n
graphic channels. Each screen can be configured with its own color depth and visual class. Multiple logical
screens can only be used with a distributed system. Each rendering machine displays one screen.
The configuration of multiple logical screens is explained in section
6.1.6 Advanced configuration of TransForm A
(geometry)
.
Note that multiple logical screens can not be used simultaneously together with the
X MultiCursor extension (XMC), see section
