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/*!
    \page qtopiacore-displaymanagement.html

    \title Qtopia Core Display Management
    \ingroup qtopiacore

    When rendering, \l {Qtopia Core}'s default behavior is for each
    client to render its widgets into memory while the server is
    responsible for putting the contents of the memory onto the
    screen. The server uses the screen driver to copy the content of
    the memory to the display.

    The screen driver is loaded by the server application when it
    starts running, using Qt's \l {How to Create Qt Plugins}{plugin
    system}.

    Contents:

    \tableofcontents

    \section1 Available Drivers

    \l {Qtopia Core} provides drivers for the Linux framebuffer, the
    virtual framebuffer, transformed screens, VNC servers and multi
    screens. Run the \c configure script to list the available
    drivers:

    \code
        ./configure -help
    \endcode

    In the default Qt configuration, only an unaccelerated Linux
    framebuffer driver (\c /dev/fb0) is enabled. The various drivers
    can be enabled and disabled using the \c configure script. For
    example:

    \code
        ./configure -qt-gfx-transformed
    \endcode

    Custom screen drivers can be implemented by subclassing the
    QScreen class and creating a screen driver plugin (derived from
    the QScreenDriverPlugin class).  \l {Qtopia Core}'s implementation
    of the QScreenDriverFactory class will automatically detect the
    plugin, loading the driver into the server application at runtime.

    \section1 Specifying a Driver

    To specify which driver to use, set the QWS_DISPLAY environment
    variable. For example (if the current shell is bash, ksh, zsh or
    sh):

    \code
        export QWS_DISPLAY="<driver>[:<driver specific options>]...
                 [:<display num>]"
    \endcode

    The valid values for the \c <driver> argument are \c LinuxFb, \c
    QVFb, \c VNC, \c Transformed, \c Multi and \l
    {QScreenDriverPlugin::keys()}{keys} identifying custom drivers,
    and the \c {<display num>} argument is used to separate screens
    that are using the same screen driver and to enable multiple
    displays (see the \l {Running Qtopia Core Applications}
    documentation for more details). The driver specific options are
    described in the table below.

    \table
    \header
        \o Driver Specific Option \o Available For  \o Description
    \row
        \o \c tty=<device>
        \o LinuxFb
        \o Passes the device file to the console the application is
        running on.
    \row
        \o \c nographicsmodeswitch
        \o LinuxFb
        \o Ensures that the application is not in graphics mode.
    \row
        \o \c mmWidth=<value> \target mmWidth
        \o LinuxFb, QVFb
        \o The screen's physical width (used to calculate DPI).
    \row
        \o \c mmHeight=<value> \target mmHeight
        \o LinuxFb, QVFb
        \o The screen's physical height (used to calculate DPI).
    \row
        \o \c <device>
        \o LinuxFb
        \o
    \row
        \o \c <subdriver>
        \o VNC, Transformed, Multi
        \o Specifies a subdriver.
    \row
        \o \c <RotX>
        \o Transformed
        \o Specifies the rotation of the screen. The valid values of
        \c X are 90, 180 and 270.
    \row
        \o \c offset=<x,y>
        \o Multi
        \o Specifies the coordinates of a subscreens top-left corner
        (by default 0,0).

    \endtable

    The QWS_DISPLAY environment variable can also be set using the \c
    -display option when running an application. For example:

    \code
        myApplication -display "<driver>[:<driver specific options>]...
                 [:<display num>]"
    \endcode

    \table 100%
    \header \o Subdrivers
    \row \o


    The VNC, Transformed and Multi screen drivers depend on
    subdrivers. The general syntax for specifying a driver is as
    follows:

    \code
        export QWS_DISPLAY="<driver>[:<subdriver>][:<subdriver options>]...
                [ :<display num>]"
    \endcode

    In the case of subdrivers, it is important to add a space between
    each subdriver and before the display number to separate the
    various drivers and displays. Note that \c Multi screen drivers
    can have several subdrivers. For example:

    \code
        export QWS_DISPLAY="Multi: QVFb:0 QVFb:offset=640,0:1 :2"
    \endcode

    Note also that the VNC screen driver defaults to a virtual screen
    driver if no subdriver is specified. In this case the VNC driver accepts a
    few additional (optional) arguments specifying the size and depth
    of the default virtual screen:

    \list
        \o \c {size=<width x height>}
        \o \c {depth=<value>}
        \o \c {mmHeight=<physical height in millimeters>}
        \o \c {mmWidth=<physical width in millimeters>}
    \endlist

    Example running the VNC screen driver with a virtual screen of size 
    720x480 with 32 bits per pixel:

    \code
	export QWS_DISPLAY="VNC:size=720x480:depth=32"
    \endcode

    Example running the VNC screen driver on top of the Linux framebuffer
    driver:

    \code
	export QWS_DISPLAY="VNC:LinuxFb"
    \endcode

    \endtable

*/
