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/****************************************************************************
**
** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** 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 widgets/symbianvibration
\group all-examples
\title Symbian Vibration Example
The Symbian Vibrator example shows how to get fine-grained vibration
control on Symbian devices.
Native Symbian APIs have to be used to enable vibration, since QtMobility
doesn't provide an interface for it yet. It is, however, planned to be
included in a future release. In anticipation for that, we make use of the
\c XQVibra class that was a part of the Mobile Extensions Technology Preview
API for Qt for Symbian. The pre-compiled libraries are no longer compatible
with Qt 4.6, but we can include the source code itself with the project.
\image symbianvibration-example.png Screenshot of the Symbian Vibration example
The example application divides the window into rectangles, which can be
pressed to make the device vibrate. Pressing different rectangles make the
device vibrate with different intensities. Each rectangle has a different
color and its intensity number is drawn on top of it. Moving the cursor
from one rectangle to another changes the vibration intensity to that of
the new one. Vibration stops when the mouse button has been released. It
is also possible to launch a short burst of vibration through the menu.
The example consists of four classes:
\list
\o \c XQVibra is the vibration interface class taken from the Mobile
Extensions for Qt for Symbian.
\o \c XQVibraPrivate is the Symbian specific private implementation of the
vibration implementation.
\o \c VibrationSurface is a custom widget that uses a XQVibra instance to
vibrate the device depending on where the user presses.
\o \c MainWindow inherits from QMainWindow and contains a \c VibrationSurface
as its central widget, and also has a menu from which it is possible to
make the phone vibrate.
\endlist
\section1 XQVibra Class Definition
The \c XQVibra class uses the pimpl-idiom to hide the platform specific
implementation behind a common interface. Technically it would be possible
to support more target platforms, with only the addition of a private
implementation. The rest of the code would work the same, since only the
common interface is used.
\snippet examples/widgets/symbianvibration/xqvibra.h 0
\c XQVibra provides a very simple interface for us to use. The interesting
part are the three slots \c start(), \c stop() and \c setIntensity(). Calling the start
method initiates vibration for the specified duration. Calling it while the
device is already vibrating causes it to stop the current one and start the
new one, even if the intensities are the same. The \c setIntensity() method
should be called before starting vibration.
\section1 VibrationSurface Class Definition
\c VibrationSurface inherits from QWidget and acts like a controller for a
\c XQVibra object. It responds to mouse events and performs custom painting.
\snippet examples/widgets/symbianvibration/vibrationsurface.h 0
The virtual event methods are reimplemented from QWidget. As can be seen,
there is no public programmable interface beyond what QWidget provides.
\section1 VibrationSurface Class Implementation
Mouse events control the intensity of the vibration.
\snippet examples/widgets/symbianvibration/vibrationsurface.cpp 0
\codeline
\snippet examples/widgets/symbianvibration/vibrationsurface.cpp 1
\codeline
\snippet examples/widgets/symbianvibration/vibrationsurface.cpp 2
Presses starts the vibration, movement changes the intensity and releases
stops the vibration. To set the right amount of vibration, the private
method \c applyIntensity() is used. It sets the vibration intensity according to
which rectangle the mouse currently resides in.
\snippet examples/widgets/symbianvibration/vibrationsurface.cpp 3
We make sure only to change the intensity if it is different than last
time, so that the vibrator isn't stopped and restarted unnecessarily.
The range of vibration intensity ranges from 0 to XQVibra::MaxIntensity. We
divide this range into a set of levels. The number of levels and the intensity
increase for each level are stored in two constants.
\snippet examples/widgets/symbianvibration/vibrationsurface.cpp 4
Each rectangle has an intensity of one \c IntensityPerLevel more than the
previous one.
\snippet examples/widgets/symbianvibration/vibrationsurface.cpp 5
The rectangles are either put in a row, if the widget's width is greater
than its height (landscape), otherwise they are put in a column (portrait).
Each rectangle's size is thus dependent on the length of the width or the
height of the widget, whichever is longer. The length is then divided by
the number of levels, which gets us either the height or the width of each
rectangle. The dx and dy specify the distance from one rectangle to the
next, which is the same as either the width or height of the rectangle.
\snippet examples/widgets/symbianvibration/vibrationsurface.cpp 6
For each level of intensity, we draw a rectangle with increasing
brightness. On top of the rectangle a text label is drawn, specifying the
intesity of this level. We use the rectangle rect as a template for
drawing, and move it down or right at each iteration.
The intensity is calculated by dividing the greater of the width and height
into \c NumberOfLevels slices.
\snippet examples/widgets/symbianvibration/vibrationsurface.cpp 7
In case the widget's geometry is too small to fit all the levels, the user
interface will not work. For simplicity, we just return 0.
When we know the axis along which the rectangles lie, we can find the one
in which the mouse cursor lie.
\snippet examples/widgets/symbianvibration/vibrationsurface.cpp 8
The final clamp of the intensity value at the end is necessary in case the
mouse coordinate lies outside the widget's geometry.
\section1 MainWindow Class Definition
Here's the definition of the \c MainWindow class:
\snippet examples/widgets/symbianvibration/mainwindow.h 0
\c MainWindow is a top level window that uses a \c XQVibra and a
\c VibrationSurface. It also adds a menu option to the menu bar which can
start a short vibration.
\section1 MainWindow Class Implementation
In the \c MainWindow constructor the \c XQVibra and the \c VibrationSurface
are created. An action is added to the menu and is connected to the vibrate
slot.
\snippet examples/widgets/symbianvibration/mainwindow.cpp 0
The \c vibrate() slot offers a way to invoke the vibration in case no
mouse is present on the device.
\snippet examples/widgets/symbianvibration/mainwindow.cpp 1
\section1 Symbian Vibration Library
The \c XQVibra class requires a platform library to be included. It is
included in the \c .pro file for the symbian target.
\quotefromfile examples/widgets/symbianvibration/symbianvibration.pro
\skipto /^symbian \{/
\printuntil /^\}/
*/
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