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/*! \example widgets/symbianvibration
    \group all-examples
    \title Symbian Vibration Example

    \brief 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 /^\}/
*/