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+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
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+****************************************************************************/
+
+/*!
+ \page qt-embedded-displaymanagement.html
+
+ \title Qt for Embedded Linux Display Management
+ \ingroup qt-embedded-linux
+
+ When rendering, the default behavior for each Qt for Embedded Linux
+ client is 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{Qt for Embedded Linux} 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:
+
+ \if defined(QTOPIA_DOCS)
+ \snippet doc/src/snippets/code/doc_src_qt-embedded-displaymanagement.qdoc 0
+ \else
+ \snippet doc/src/snippets/code/doc_src_qt-embedded-displaymanagement.qdoc 1
+ \endif
+
+ \if defined(QTOPIA_DOCS)
+ In the default Qt Extended 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:
+
+ \snippet doc/src/snippets/code/doc_src_qt-embedded-displaymanagement.qdoc 2
+ \else
+ 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:
+
+ \snippet doc/src/snippets/code/doc_src_qt-embedded-displaymanagement.qdoc 3
+ \endif
+
+ Custom screen drivers can be implemented by subclassing the
+ QScreen class and creating a screen driver plugin (derived from
+ the QScreenDriverPlugin class). The default implementation
+ of the QScreenDriverFactory class will automatically detect the
+ plugin, loading the driver into the server application at run-time.
+
+ \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):
+
+ \snippet doc/src/snippets/code/doc_src_qt-embedded-displaymanagement.qdoc 4
+
+ 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 Qt for Embedded Linux 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 littleendian
+ \o LinuxFb
+ \o Tells the driver it must handle a little-endian frame
+ buffer in a big-endian system.
+ \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 subscreen's 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:
+
+ \snippet doc/src/snippets/code/doc_src_qt-embedded-displaymanagement.qdoc 5
+
+ \section1 Subdrivers and Multiple Drivers
+
+ The VNC, Transformed and Multi screen drivers depend on
+ subdrivers. The general syntax for specifying a driver is as
+ follows:
+
+ \snippet doc/src/snippets/code/doc_src_qt-embedded-displaymanagement.qdoc 6
+
+ 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:
+
+ \snippet doc/src/snippets/code/doc_src_qt-embedded-displaymanagement.qdoc 7
+
+ 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:
+
+ \snippet doc/src/snippets/code/doc_src_qt-embedded-displaymanagement.qdoc 8
+
+ Example running the VNC screen driver on top of the Linux framebuffer
+ driver:
+
+ \snippet doc/src/snippets/code/doc_src_qt-embedded-displaymanagement.qdoc 9
+
+ In this last example, Qt is using two screen drivers simultaneously,
+ displaying output on both the device's screen and across a network on
+ VNC client displays.
+*/