source: trunk/doc/src/emb-pointer.qdoc@ 172

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/*!
    \page qt-embedded-pointer.html

    \title Qt for Embedded Linux Pointer Handling
    \ingroup qt-embedded-linux

    When running a \l{Qt for Embedded Linux} application, it either runs as a
    server or connects to an existing server. The mouse driver is
    loaded by the server application when it starts running, using
    Qt's \l {How to Create Qt Plugins}{plugin system}.

    Internally in the client/server protocol, all system generated
    events, including pointer events, are passed to the server
    application which then propagates the event to the appropriate
    client. Note that pointer handling in \l{Qt for Embedded Linux} works for
    both mouse and mouse-like devices such as touch panels and
    trackballs.

    Contents:

    \tableofcontents

    \section1 Available Drivers

    \l{Qt for Embedded Linux} provides ready-made drivers for the MouseMan,
    IntelliMouse, Microsoft, NEC Vr41XX, Linux Touch Panel and Yopy
    protocols as well as the universal touch screen library,
    tslib. Run the \c configure script to list the available drivers:

    \if defined(QTOPIA_PHONE)

        \snippet doc/src/snippets/code/doc_src_emb-pointer.qdoc 0

        \bold{Note:} By default only the PC mouse driver is enabled.

        The various drivers can be enabled and disabled using the \c
        configure script. For example:

        \snippet doc/src/snippets/code/doc_src_emb-pointer.qdoc 1

    \else

        \snippet doc/src/snippets/code/doc_src_emb-pointer.qdoc 2

        In the default Qt configuration, only the "pc" mouse driver is
        enabled. The various drivers can be enabled and disabled using
        the \c configure script. For example:

        \snippet doc/src/snippets/code/doc_src_emb-pointer.qdoc 3
    \endif

    Custom mouse drivers can be implemented by subclassing the
    QWSMouseHandler class and creating a mouse driver plugin (derived
    from the QMouseDriverPlugin class). The default implementation of the
    QMouseDriverFactory class will automatically detect the plugin,
    loading the driver into the server application at run-time.

    If you are creating a driver for a device that needs calibration
    or noise reduction, such as a touchscreen, derive from the
    QWSCalibratedMouseHandler subclass instead to take advantage of
    its calibration functionality.

    \if defined(QTOPIA_PHONE)
        For a tutorial on how to add a new keyboard driver plug-in
        see: \l {Tutorial: Implementing a Device Plug-in}.
    \endif

    \section1 Specifying a Driver

    Provided that the "pc" mouse driver is enabled, \l{Qt for Embedded Linux} will
    try to auto-detect the mouse device if it is one of the supported
    types on \c /dev/psaux or one of the \c /dev/ttyS?  serial
    lines. If multiple mice are detected, all may be used
    simultaneously.

    Note that \l{Qt for Embedded Linux} does not support auto-detection of \e
    {touch panels} in which case the driver must be specified
    explicitly to determine which device to use.

    To manually specify which driver to use, set the QWS_MOUSE_PROTO
    environment variable. For example (if the current shell is bash,
    ksh, zsh or sh):

    \snippet doc/src/snippets/code/doc_src_emb-pointer.qdoc 4

    The valid values for the \c <driver> argument are \c MouseMan, \c
    IntelliMouse, \c Microsoft, \c VR41xx, \c LinuxTP, \c Yopy, \c
    Tslib and \l {QMouseDriverPlugin::keys()}{keys} identifying custom
    drivers, and the driver specific options are typically a device,
    e.g., \c /dev/mouse for mouse devices and \c /dev/ts for touch
    panels.

    Multiple mouse drivers can be specified in one go:

    \snippet doc/src/snippets/code/doc_src_emb-pointer.qdoc 5

    Input will be read from all specified drivers.

    Note that the \c Vr41xx driver also accepts two optional
    arguments: \c press=<value> defining a mouse click (the default
    value is 750) and \c filter=<value> specifying the length of the
    filter used to eliminate noise (the default length is 3). For
    example:

    \snippet doc/src/snippets/code/doc_src_emb-pointer.qdoc 6

    \table
    \header \o The Tslib Mouse Driver
    \row
    \o

    The tslib mouse driver inherits the QWSCalibratedMouseHandler
    class, providing calibration and noise reduction functionality in
    addition to generating mouse events for devices using the
    Universal Touch Screen Library.

    To be able to compile this mouse handler, \l{Qt for Embedded Linux} must be
    configured with the \c -qt-mouse-tslib option as described
    above. In addition, the tslib headers and library must be present
    in the build environment.

    The tslib sources can be downloaded from \l
    http://tslib.berlios.de. Use the \c configure script's -L and
    -I options to explicitly specify the location of the library and
    its headers:

    \snippet doc/src/snippets/code/doc_src_emb-pointer.qdoc 7

    In order to use this mouse driver, tslib must also be correctly
    installed on the target machine. This includes providing a \c
    ts.conf configuration file and setting the neccessary environment
    variables (see the README file provided with tslib for details).

    The \c ts.conf file will usually contain the following two lines:

    \snippet doc/src/snippets/code/doc_src_emb-pointer.qdoc 8

    To make \l{Qt for Embedded Linux} explicitly choose the tslib mouse
    handler, set the QWS_MOUSE_PROTO environment variable as explained
    above.

    \endtable

    \section1 Troubleshooting

    \section2 Device Files

    Make sure you are using the correct device file.

    As a first step, you can test whether the device file actually gives any
    output. For instance, if you have specified the mouse driver with
    \snippet doc/src/snippets/code/doc_src_emb-pointer.qdoc 9
    then try examining
    the output from the device by entering the following command in a console:
    \snippet doc/src/snippets/code/doc_src_emb-pointer.qdoc 10

    If you see output from the device printed on the console when you move
    the mouse, you are probably using the correct device file; otherwise, you
    will need to experiment to find the correct device file.

    \section2 File Permissions

    Make sure you have sufficient permissions to access the device file.

    The Qt for Embedded Linux server process needs at least read permission for the 
    device file. Some drivers also require write access to the device file. 
    For instance, if you have specified the mouse driver with
    \snippet doc/src/snippets/code/doc_src_emb-pointer.qdoc 11
    then examine the permissions of the device file by entering the following
    command in a console:
    \snippet doc/src/snippets/code/doc_src_emb-pointer.qdoc 12

    If the device file is actually a symbolic link to another file, you must
    change the permissions of the actual file instead.
*/