Doc: Removed Double Buffer example.

-The example no longer exists

Change-Id: I05485e950ca39918117cddee928f3c9da0fe1cb8
Reviewed-by: Paul Olav Tvete <paul.tvete@nokia.com>
Reviewed-by: Martin Smith <martin.smith@nokia.com>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>

diff --git a/doc/src/examples/dbscreen.qdoc b/doc/src/examples/dbscreen.qdoc
deleted file mode 100644 (file)
index bfecb9a..0000000
--- a/doc/src/examples/dbscreen.qdoc
+++ /dev/null
@@ -1,186 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
-** Contact: http://www.qt-project.org/
-**
-** This file is part of the documentation of the Qt Toolkit.
-**
-** $QT_BEGIN_LICENSE:FDL$
-** GNU Free Documentation License
-** Alternatively, this file may be used under the terms of the GNU Free
-** Documentation License version 1.3 as published by the Free Software
-** Foundation and appearing in the file included in the packaging of
-** this file.
-**
-** Other Usage
-** Alternatively, this file may be used in accordance with the terms
-** and conditions contained in a signed written agreement between you
-** and Nokia.
-**
-**
-**
-**
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-/*!
-    \example qws/dbscreen
-    \title Double Buffered Graphics Driver Example
-
-    The Double Buffered Graphics Driver example shows how to write your own
-    double buffered graphics driver and add it to Qt for Embedded Linux.
-
-    Similar to the \l{Accelerated Graphics Driver Example}, there are three steps
-    to writing and implementing this graphics driver:
-
-    \list 1
-        \li \l {Step 1: Creating a Custom Graphics Driver}
-        {Creating a Custom Graphics Driver}
-
-        \li \l {Step 2: Implementing the Back Buffer}
-        {Implementing the Back Buffer}
-
-        \li \l {Step 3: Creating the Driver Plugin}
-        {Creating the Driver Plugin}
-
-    \endlist
-
-    After compiling the example code, install the graphics driver plugin with
-    the command \c {make install}. To start an application using the graphics
-    driver, you can either set the environment variable \l QWS_DISPLAY and
-    then run the application, or you can just run the application using the
-    \c -display switch.
-
-    Note that this is a minimal example and this driver will not work well
-    with widgets painting themself directly to the screen (e.g. widgets with
-    the Qt::WA_PaintOnScreen window attribute set). Also, the example requires
-    the Linux framebuffer to be set up correctly and with the correct device
-    permissions. For further information, refer to
-    \l{Testing the Linux Framebuffer}.
-
-    \section1 Step 1: Creating a Custom Graphics Driver
-
-    Usually, a custom graphics driver is created by subclassing the QScreen
-    class, the base class for implementing screen or graphics drivers in
-    Qt for Embedded Linux. In this example, however, we subclass the QLinuxFbScreen
-    class instead, to ensure that our driver uses the Linux framebuffer.
-
-    For our graphics driver, the \c DBScreen class, we reimplement five
-    functions belonging to QScreen:
-
-    \list
-        \li \l{QScreen::initDevice()}{initDevice()},
-        \li \l{QScreen::shutdownDevice()}{shutdownDevice()},
-        \li \l{QScreen::blit()}{blit()},
-        \li \l{QScreen::solidFill()}{solidFill()}, and
-        \li \l{QScreen::exposeRegion()}{exposeRegion()}.
-    \endlist
-
-    \snippet examples/qws/dbscreen/dbscreen.h 0
-
-    In addition to the abovementioned functions, there is a private instance
-    of QPainter and QImage - \c painter, used for drawing operations on
-    the back buffer, and \c image, the back buffer itself.
-
-    \section1 Step 2: Implementing the Back Buffer
-
-    The graphics driver must carry out three main functions:
-
-    \list 1
-        \li Allocate the back buffer on startup and deallocate it on shutdown.
-        \li Draw to the back buffer instead of directly to the screen
-           (which is what QLinuxFbScreen does).
-        \li Copy the back buffer to the screen whenever a screen update is
-           done.
-    \endlist
-
-    \section2 Device initializing and shutdown 
-
-    We first reimplement \c initDevice() and \c shutdownDevice().
-
-    The \c initDevice() function initializes the framebuffer. We reimplement
-    this function to enable accelerated drivers to set up the graphic card.
-    For this example, we first call the super class' implementation to set up
-    the Linux framebuffer. If this call returns \c false, we return \c false.
-    Otherwise, we initialize the screen cursor with
-    QScreenCursor::initSoftwareCursor() as well as instantiate \c image and
-    \c painter. Then, we return \c true.
-
-    \snippet examples/qws/dbscreen/dbscreen.cpp 0
-
-    The \c shutdownDevice() function's default implementation only hides the
-    mouse cursor. Hence, we reimplement it to carry out the necessary cleanup
-    before the Qt for Embedded Linux server exits.
-
-    \snippet examples/qws/dbscreen/dbscreen.cpp 1
-
-    Again, we call the super class implementation to shutdown the Linux
-    framebuffer prior to deleting \c image and \c painter.
-
-    \section2 Drawing to the back buffer
-
-    We move on to the drawing functions - \c solidFill() and \c blit(). In
-    QLinuxFbScreen, these functions draw directly to the Linux framebuffer;
-    but in our driver we reimplement them to draw to the back buffer instead.
-
-    \snippet examples/qws/dbscreen/dbscreen.cpp 2
-
-    The \c solidFill() function is called from \c exposeRegion() to fill the
-    given \c region of the screen with the specified \c color. In this
-    example, we use \c painter to fill rectangles in \c image, the back
-    buffer, according to the given region.
-
-    \snippet examples/qws/dbscreen/dbscreen.cpp 3
-
-    The \c blit() function is also called from \c exposeRegion() to copy the
-    given QRegion object, \c region, in the given QImage object, \c image, to
-    the QPoint object specified by \c topLeft. Once again we use \c painter
-    to draw in the back buffer, \c image.
-
-    \section2 Displaying the buffer on the screen
-
-    The \c exposeRegion() function is called by the Qt for Embedded Linux server
-    whenever a screen update is required. The given \c region is the screen
-    region that needs to be updated and \c changing is is the index into
-    QWSServer::clientWindows() of the window that caused the update.
-
-    \snippet examples/qws/dbscreen/dbscreen.cpp 4
-
-    In our implementation, we first call the super class implementation to
-    ensure that \c solidFill() and \c blit() will be called correctly. This
-    causes the changed areas to be updated in the back buffer. We then call
-    the super class' implementation of \c blit() to copy the updated region
-    from the back buffer into the Linux framebuffer.
-
-    \section1 Step 3: Creating the Driver Plugin
-
-    Qt provides a high level API for writing Qt extensions. One of the plugin
-    base classes provided is QScreenDriverPlugin, which we use in this example
-    to create our screen driver plugin.
-
-    \snippet examples/qws/dbscreen/dbscreendriverplugin.cpp 0
-
-    There are only two functions to reimplement:
-
-    \list
-        \li \l{QScreenDriverPlugin::create()}{create()} - creates a driver
-           matching the given key
-        \li \l{QScreenDriverPlugin::create()}{keys()} - returns a list of
-           valid keys representing the drivers supported by the plugin
-    \endlist
-
-    \snippet examples/qws/dbscreen/dbscreendriverplugin.cpp 1
-    \codeline
-    \snippet examples/qws/dbscreen/dbscreendriverplugin.cpp 2
-
-    Our plugin will only support one driver, \c dbscreen.
-
-    Lastly, we export the plugin.
-
-    \snippet examples/qws/dbscreen/dbscreendriverplugin.cpp 3
-
-    For detailed information about the Qt plugin system see
-    \l{How to Create Qt Plugins.}
-*/