qmouse_qws.cpp

奇趣公司比较新的qt/emd版本

    calibration parameters is written to and read from the file
    currently specified by the POINTERCAL_FILE environment variable;
    the default file is \c /etc/pointercal.

    To achieve noise reduction, QWSCalibratedMouseHandler provides the
    sendFiltered() function. Use this function instead of
    mouseChanged() whenever a mouse event occurs. The filter's size
    can be manipulated using the setFilterSize() function.

    \sa QWSMouseHandler, QWSPointerCalibrationData,
    {qtopiacore/mousecalibration}{Mouse Calibration Example}
*/


/*!
    \internal
 */

QWSCalibratedMouseHandler::QWSCalibratedMouseHandler(const QString &, const QString &)
    : samples(5), currSample(0), numSamples(0)
{
    clearCalibration();
    readCalibration();
}

/*!
    Fills \a cd with the device coordinates corresponding to the given
    screen coordinates.

    \internal
*/
void QWSCalibratedMouseHandler::getCalibration(QWSPointerCalibrationData *cd) const
{
    const qint64 scale = qint64(a) * qint64(e) - qint64(b) * qint64(d);
    const qint64 xOff = qint64(b) * qint64(f) - qint64(c) * qint64(e);
    const qint64 yOff = qint64(c) * qint64(d) - qint64(a) * qint64(f);
    for (int i = 0; i <= QWSPointerCalibrationData::LastLocation; ++i) {
        const qint64 sX = cd->screenPoints[i].x();
        const qint64 sY = cd->screenPoints[i].y();
        const qint64 dX = (s*(e*sX - b*sY) + xOff) / scale;
        const qint64 dY = (s*(a*sY - d*sX) + yOff) / scale;
        cd->devPoints[i] = QPoint(dX, dY);
    }
}

/*!
    Clears the current calibration, i.e., makes the mouse
    driver return mouse events in raw device coordinates instead of
    screen coordinates.

    \sa calibrate()
*/
void QWSCalibratedMouseHandler::clearCalibration()
{
    a = 1;
    b = 0;
    c = 0;
    d = 0;
    e = 1;
    f = 0;
    s = 1;
}


/*!
    Saves the current calibration parameters in \c /etc/pointercal
    (separated by whitespace and in alphabetical order).

    You can override the default \c /etc/pointercal by specifying
    another file using the POINTERCAL_FILE environment variable.

    \sa readCalibration()
*/
void QWSCalibratedMouseHandler::writeCalibration()
{
    QString calFile;
    calFile = QString::fromLocal8Bit(qgetenv("POINTERCAL_FILE"));
    if (calFile.isEmpty())
        calFile = QLatin1String("/etc/pointercal");

#ifndef QT_NO_TEXTSTREAM
    QFile file(calFile);
    if (file.open(QIODevice::WriteOnly)) {
        QTextStream t(&file);
        t << a << " " << b << " " << c << " ";
        t << d << " " << e << " " << f << " " << s;
    } else
#endif
    {
        qCritical("QWSCalibratedMouseHandler::writeCalibration: "
                  "Could not save calibration into %s", qPrintable(calFile));
    }
}

/*!
    Reads previously written calibration parameters which are stored
    in \c /etc/pointercal (separated by whitespace and in alphabetical
    order).

    You can override the default \c /etc/pointercal by specifying
    another file using the POINTERCAL_FILE environment variable.


    \sa writeCalibration()
*/
void QWSCalibratedMouseHandler::readCalibration()
{
    QString calFile = QString::fromLocal8Bit(qgetenv("POINTERCAL_FILE"));
    if (calFile.isEmpty())
        calFile = QLatin1String("/etc/pointercal");

#ifndef QT_NO_TEXTSTREAM
    QFile file(calFile);
    if (file.open(QIODevice::ReadOnly)) {
        QTextStream t(&file);
        t >> a >> b >> c >> d >> e >> f >> s;
        if (s == 0 || t.status() != QTextStream::Ok) {
            qCritical("Corrupt calibration data");
            clearCalibration();
        }
    } else
#endif
    {
        qDebug() << "Could not read calibration:" <<calFile;
    }
}

static int ilog2(quint32 n)
{
    int result = 0;

    if (n & 0xffff0000) {
        n >>= 16;
        result += 16;
    }
    if (n & 0xff00) {
        n >>= 8;
        result += 8;}
    if (n & 0xf0) {
        n >>= 4;
        result += 4;
    }
    if (n & 0xc) {
        n >>= 2;
        result += 2;
    }
    if (n & 0x2)
        result += 1;

    return result;
}

/*!
    Updates the calibration parameters based on coordinate mapping of
    the given \a data.

    Create an instance of the QWSPointerCalibrationData class, fill in
    the device and screen coordinates and pass that object to the mouse
    driver using this function.

    \sa clearCalibration(), transform()
*/
void QWSCalibratedMouseHandler::calibrate(const QWSPointerCalibrationData *data)
{
    // Algorithm derived from
    // "How To Calibrate Touch Screens" by Carlos E. Vidales,
    // printed in Embedded Systems Programming, Vol. 15 no 6, June 2002
    // URL: http://www.embedded.com/showArticle.jhtml?articleID=9900629

    const QPoint pd0 = data->devPoints[QWSPointerCalibrationData::TopLeft];
    const QPoint pd1 = data->devPoints[QWSPointerCalibrationData::TopRight];
    const QPoint pd2 = data->devPoints[QWSPointerCalibrationData::BottomRight];
    const QPoint p0 = data->screenPoints[QWSPointerCalibrationData::TopLeft];
    const QPoint p1 = data->screenPoints[QWSPointerCalibrationData::TopRight];
    const QPoint p2 = data->screenPoints[QWSPointerCalibrationData::BottomRight];

    const qint64 xd0 = pd0.x();
    const qint64 xd1 = pd1.x();
    const qint64 xd2 = pd2.x();
    const qint64 yd0 = pd0.y();
    const qint64 yd1 = pd1.y();
    const qint64 yd2 = pd2.y();
    const qint64 x0 = p0.x();
    const qint64 x1 = p1.x();
    const qint64 x2 = p2.x();
    const qint64 y0 = p0.y();
    const qint64 y1 = p1.y();
    const qint64 y2 = p2.y();

    qint64 scale = ((xd0 - xd2)*(yd1 - yd2) - (xd1 - xd2)*(yd0 - yd2));
    int shift = 0;
    qint64 absScale = qAbs(scale);
    // use maximum 16 bit precision to reduce risk of integer overflow
    if (absScale > (1 << 16)) {
        shift = ilog2(absScale >> 16) + 1;
        scale >>= shift;
    }

    s = scale;
    a = ((x0 - x2)*(yd1 - yd2) - (x1 - x2)*(yd0 - yd2)) >> shift;
    b = ((xd0 - xd2)*(x1 - x2) - (x0 - x2)*(xd1 - xd2)) >> shift;
    c = (yd0*(xd2*x1 - xd1*x2) + yd1*(xd0*x2 - xd2*x0) + yd2*(xd1*x0 - xd0*x1)) >> shift;
    d = ((y0 - y2)*(yd1 - yd2) - (y1 - y2)*(yd0 - yd2)) >> shift;
    e = ((xd0 - xd2)*(y1 - y2) - (y0 - y2)*(xd1 - xd2)) >> shift;
    f = (yd0*(xd2*y1 - xd1*y2) + yd1*(xd0*y2 - xd2*y0) + yd2*(xd1*y0 - xd0*y1)) >> shift;

    writeCalibration();
}

/*!
    Transforms the given \a position from device coordinates to screen
    coordinates, and returns the transformed position.

    This function is typically called explicitly on the points passed
    to the QWSMouseHandler::mouseChanged() function.

    This implementation is a linear transformation using 7 parameters
    (\c a, \c b, \c c, \c d, \c e, \c f and \c s) to transform the
    device coordinates (\c Xd, \c Yd) into screen coordinates (\c Xs,
    \c Ys) using the following equations:

    \code
        s*Xs = a*Xd + b*Yd + c
        s*Ys = d*Xd + e*Yd + f
    \endcode

    \sa mouseChanged()
*/
QPoint QWSCalibratedMouseHandler::transform(const QPoint &position)
{
    QPoint tp;

    tp.setX((a * position.x() + b * position.y() + c) / s);
    tp.setY((d * position.x() + e * position.y() + f) / s);

    return tp;
}

/*!
    Sets the size of the filter used in noise reduction to the given
    \a size.

    The sendFiltered() function reduces noice by calculating an
    average position from a collection of mouse event positions. The
    filter size determines the number of positions that forms the
    basis for these calculations.

    \sa sendFiltered()
*/
void QWSCalibratedMouseHandler::setFilterSize(int size)
{
    samples.resize(qMax(1, size));
    numSamples = 0;
    currSample = 0;
}

/*!
    \fn bool QWSCalibratedMouseHandler::sendFiltered(const QPoint &position, int state)

    Notifies the system of a new mouse event \e after applying a noise
    reduction filter. Returns true if the filtering process is
    successful; otherwise returns false. Note that if the filtering
    process failes, the system is not notified about the event.

    The given \a position is the global position of the mouse. The \a
    state parameter is a bitmask of the Qt::MouseButton enum's values
    indicating which mouse buttons are pressed.

    The noice is reduced by calculating an average position from a
    collection of mouse event positions and then calling the
    mouseChanged() function with the new position. The number of
    positions that is used is determined by the filter size.

    \sa mouseChanged(), setFilterSize()
*/
bool QWSCalibratedMouseHandler::sendFiltered(const QPoint &position, int button)
{
    if (!button) {
        if (numSamples >= samples.count())
            mouseChanged(transform(position), 0);
        currSample = 0;
        numSamples = 0;
        return true;
    }

    bool sent = false;
    samples[currSample] = position;
    numSamples++;
    if (numSamples >= samples.count()) {

        int ignore = -1;
        if (samples.count() > 2) { // throw away the "worst" sample
            int maxd = 0;
            for (int i = 0; i < samples.count(); i++) {
                int d = (mousePos - samples[i]).manhattanLength();
                if (d > maxd) {
                    maxd = d;
                    ignore = i;
                }
            }
        }

        // average the rest
        QPoint pos(0, 0);
        int numAveraged = 0;
        for (int i = 0; i < samples.count(); i++) {
            if (ignore == i)
                continue;
            pos += samples[i];
            ++numAveraged;
        }
        if (numAveraged)
            pos /= numAveraged;

        mouseChanged(transform(pos), button);
        sent = true;
    }
    currSample++;
    if (currSample >= samples.count())
        currSample = 0;

    return sent;
}