diff options
Diffstat (limited to 'doc/src/platforms/emb-displaymanagement.qdoc')
| -rw-r--r-- | doc/src/platforms/emb-displaymanagement.qdoc | 205 |
1 files changed, 205 insertions, 0 deletions
diff --git a/doc/src/platforms/emb-displaymanagement.qdoc b/doc/src/platforms/emb-displaymanagement.qdoc new file mode 100644 index 0000000..8a743b1 --- /dev/null +++ b/doc/src/platforms/emb-displaymanagement.qdoc @@ -0,0 +1,205 @@ +/**************************************************************************** +** +** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies). +** Contact: Nokia Corporation (qt-info@nokia.com) +** +** This file is part of the documentation of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL$ +** No Commercial Usage +** This file contains pre-release code and may not be distributed. +** You may use this file in accordance with the terms and conditions +** contained in the either Technology Preview License Agreement or the +** Beta Release License Agreement. +** +** GNU Lesser General Public License Usage +** Alternatively, this file may be used under the terms of the GNU Lesser +** General Public License version 2.1 as published by the Free Software +** Foundation and appearing in the file LICENSE.LGPL included in the +** packaging of this file. Please review the following information to +** ensure the GNU Lesser General Public License version 2.1 requirements +** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. +** +** In addition, as a special exception, Nokia gives you certain +** additional rights. These rights are described in the Nokia Qt LGPL +** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this +** package. +** +** GNU General Public License Usage +** Alternatively, this file may be used under the terms of the GNU +** General Public License version 3.0 as published by the Free Software +** Foundation and appearing in the file LICENSE.GPL included in the +** packaging of this file. Please review the following information to +** ensure the GNU General Public License version 3.0 requirements will be +** met: http://www.gnu.org/copyleft/gpl.html. +** +** If you are unsure which license is appropriate for your use, please +** contact the sales department at http://qt.nokia.com/contact. +** $QT_END_LICENSE$ +** +****************************************************************************/ + +/*! + \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 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: + + \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. +*/ |