path: root/src/quick/util/qdeclarativepath.cpp

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#include "qdeclarativepath_p.h"
#include "qdeclarativepath_p_p.h"
#include "qdeclarativesvgparser_p.h"

#include <QSet>
#include <QTime>

#include <private/qbezier_p.h>
#include <QtCore/qmath.h>
#include <QtCore/qnumeric.h>

QT_BEGIN_NAMESPACE

/*!
    \qmlclass PathElement QDeclarativePathElement
    \inqmlmodule QtQuick 2
    \ingroup qml-view-elements
    \brief PathElement is the base path type.

    This type is the base for all path types.  It cannot
    be instantiated.

    \sa Path, PathAttribute, PathPercent, PathLine, PathQuad, PathCubic, PathArc, PathCurve, PathSvg
*/

/*!
    \qmlclass Path QDeclarativePath
    \inqmlmodule QtQuick 2
    \ingroup qml-view-elements
    \brief A Path object defines a path for use by \l PathView.

    A Path is composed of one or more path segments - PathLine, PathQuad,
    PathCubic, PathArc, PathCurve, PathSvg.

    The spacing of the items along the Path can be adjusted via a
    PathPercent object.

    PathAttribute allows named attributes with values to be defined
    along the path.

    \sa PathView, PathAttribute, PathPercent, PathLine, PathQuad, PathCubic, PathArc, PathCurve, PathSvg
*/
QDeclarativePath::QDeclarativePath(QObject *parent)
 : QObject(*(new QDeclarativePathPrivate), parent)
{
}

QDeclarativePath::~QDeclarativePath()
{
}

/*!
    \qmlproperty real QtQuick2::Path::startX
    \qmlproperty real QtQuick2::Path::startY
    These properties hold the starting position of the path.
*/
qreal QDeclarativePath::startX() const
{
    Q_D(const QDeclarativePath);
    return d->startX.isNull ? 0 : d->startX.value;
}

void QDeclarativePath::setStartX(qreal x)
{
    Q_D(QDeclarativePath);
    if (d->startX.isValid() && qFuzzyCompare(x, d->startX))
        return;
    d->startX = x;
    emit startXChanged();
    processPath();
}

bool QDeclarativePath::hasStartX() const
{
    Q_D(const QDeclarativePath);
    return d->startX.isValid();
}

qreal QDeclarativePath::startY() const
{
    Q_D(const QDeclarativePath);
    return d->startY.isNull ? 0 : d->startY.value;
}

void QDeclarativePath::setStartY(qreal y)
{
    Q_D(QDeclarativePath);
    if (d->startY.isValid() && qFuzzyCompare(y, d->startY))
        return;
    d->startY = y;
    emit startYChanged();
    processPath();
}

bool QDeclarativePath::hasStartY() const
{
    Q_D(const QDeclarativePath);
    return d->startY.isValid();
}

/*!
    \qmlproperty bool QtQuick2::Path::closed
    This property holds whether the start and end of the path are identical.
*/
bool QDeclarativePath::isClosed() const
{
    Q_D(const QDeclarativePath);
    return d->closed;
}

bool QDeclarativePath::hasEnd() const
{
    Q_D(const QDeclarativePath);
    for (int i = d->_pathElements.count() - 1; i > -1; --i) {
        if (QDeclarativeCurve *curve = qobject_cast<QDeclarativeCurve *>(d->_pathElements.at(i))) {
            if ((!curve->hasX() && !curve->hasRelativeX()) || (!curve->hasY() && !curve->hasRelativeY()))
                return false;
            else
                return true;
        }
    }
    return hasStartX() && hasStartY();
}

/*!
    \qmlproperty list<PathElement> QtQuick2::Path::pathElements
    This property holds the objects composing the path.

    \default

    A path can contain the following path objects:
    \list
        \i \l PathLine - a straight line to a given position.
        \i \l PathQuad - a quadratic Bezier curve to a given position with a control point.
        \i \l PathCubic - a cubic Bezier curve to a given position with two control points.
        \i \l PathArc - an arc to a given position with a radius.
        \i \l PathSvg - a path specified as an SVG path data string.
        \i \l PathCurve - a point on a Catmull-Rom curve.
        \i \l PathAttribute - an attribute at a given position in the path.
        \i \l PathPercent - a way to spread out items along various segments of the path.
    \endlist

    \snippet doc/src/snippets/declarative/pathview/pathattributes.qml 2
*/

QDeclarativeListProperty<QDeclarativePathElement> QDeclarativePath::pathElements()
{
    Q_D(QDeclarativePath);
    return QDeclarativeListProperty<QDeclarativePathElement>(this, d->_pathElements);
}

void QDeclarativePath::interpolate(int idx, const QString &name, qreal value)
{
    Q_D(QDeclarativePath);
    interpolate(d->_attributePoints, idx, name, value);
}

void QDeclarativePath::interpolate(QList<AttributePoint> &attributePoints, int idx, const QString &name, qreal value)
{
    if (!idx)
        return;

    qreal lastValue = 0;
    qreal lastPercent = 0;
    int search = idx - 1;
    while(search >= 0) {
        const AttributePoint &point = attributePoints.at(search);
        if (point.values.contains(name)) {
            lastValue = point.values.value(name);
            lastPercent = point.origpercent;
            break;
        }
        --search;
    }

    ++search;

    const AttributePoint &curPoint = attributePoints.at(idx);

    for (int ii = search; ii < idx; ++ii) {
        AttributePoint &point = attributePoints[ii];

        qreal val = lastValue + (value - lastValue) * (point.origpercent - lastPercent) / (curPoint.origpercent - lastPercent);
        point.values.insert(name, val);
    }
}

void QDeclarativePath::endpoint(const QString &name)
{
    Q_D(QDeclarativePath);
    const AttributePoint &first = d->_attributePoints.first();
    qreal val = first.values.value(name);
    for (int ii = d->_attributePoints.count() - 1; ii >= 0; ii--) {
        const AttributePoint &point = d->_attributePoints.at(ii);
        if (point.values.contains(name)) {
            for (int jj = ii + 1; jj < d->_attributePoints.count(); ++jj) {
                AttributePoint &setPoint = d->_attributePoints[jj];
                setPoint.values.insert(name, val);
            }
            return;
        }
    }
}

void QDeclarativePath::endpoint(QList<AttributePoint> &attributePoints, const QString &name)
{
    const AttributePoint &first = attributePoints.first();
    qreal val = first.values.value(name);
    for (int ii = attributePoints.count() - 1; ii >= 0; ii--) {
        const AttributePoint &point = attributePoints.at(ii);
        if (point.values.contains(name)) {
            for (int jj = ii + 1; jj < attributePoints.count(); ++jj) {
                AttributePoint &setPoint = attributePoints[jj];
                setPoint.values.insert(name, val);
            }
            return;
        }
    }
}

static QString percentString(QLatin1String("_qfx_percent"));

void QDeclarativePath::processPath()
{
    Q_D(QDeclarativePath);

    if (!d->componentComplete)
        return;

    d->_pointCache.clear();
    d->prevBez.isValid = false;

    d->_path = createPath(QPointF(), QPointF(), d->_attributes, d->pathLength, d->_attributePoints, &d->closed);

    emit changed();
}

QPainterPath QDeclarativePath::createPath(const QPointF &startPoint, const QPointF &endPoint, const QStringList &attributes, qreal &pathLength, QList<AttributePoint> &attributePoints, bool *closed)
{
    Q_D(QDeclarativePath);

    pathLength = 0;
    attributePoints.clear();

    if (!d->componentComplete)
        return QPainterPath();

    QPainterPath path;

    AttributePoint first;
    for (int ii = 0; ii < attributes.count(); ++ii)
        first.values[attributes.at(ii)] = 0;
    attributePoints << first;

    qreal startX = d->startX.isValid() ? d->startX.value : startPoint.x();
    qreal startY = d->startY.isValid() ? d->startY.value : startPoint.y();
    path.moveTo(startX, startY);

    bool usesPercent = false;
    int index = 0;
    foreach (QDeclarativePathElement *pathElement, d->_pathElements) {
        if (QDeclarativeCurve *curve = qobject_cast<QDeclarativeCurve *>(pathElement)) {
            QDeclarativePathData data;
            data.index = index;
            data.endPoint = endPoint;
            data.curves = d->_pathCurves;
            curve->addToPath(path, data);
            AttributePoint p;
            p.origpercent = path.length();
            attributePoints << p;
            ++index;
        } else if (QDeclarativePathAttribute *attribute = qobject_cast<QDeclarativePathAttribute *>(pathElement)) {
            AttributePoint &point = attributePoints.last();
            point.values[attribute->name()] = attribute->value();
            interpolate(attributePoints, attributePoints.count() - 1, attribute->name(), attribute->value());
        } else if (QDeclarativePathPercent *percent = qobject_cast<QDeclarativePathPercent *>(pathElement)) {
            AttributePoint &point = attributePoints.last();
            point.values[percentString] = percent->value();
            interpolate(attributePoints, attributePoints.count() - 1, percentString, percent->value());
            usesPercent = true;
        }
    }

    // Fixup end points
    const AttributePoint &last = attributePoints.last();
    for (int ii = 0; ii < attributes.count(); ++ii) {
        if (!last.values.contains(attributes.at(ii)))
            endpoint(attributePoints, attributes.at(ii));
    }
    if (usesPercent && !last.values.contains(percentString)) {
        d->_attributePoints.last().values[percentString] = 1;
        interpolate(d->_attributePoints.count() - 1, percentString, 1);
    }


    // Adjust percent
    qreal length = path.length();
    qreal prevpercent = 0;
    qreal prevorigpercent = 0;
    for (int ii = 0; ii < attributePoints.count(); ++ii) {
        const AttributePoint &point = attributePoints.at(ii);
        if (point.values.contains(percentString)) { //special string for QDeclarativePathPercent
            if ( ii > 0) {
                qreal scale = (attributePoints[ii].origpercent/length - prevorigpercent) /
                            (point.values.value(percentString)-prevpercent);
                attributePoints[ii].scale = scale;
            }
            attributePoints[ii].origpercent /= length;
            attributePoints[ii].percent = point.values.value(percentString);
            prevorigpercent = attributePoints[ii].origpercent;
            prevpercent = attributePoints[ii].percent;
        } else {
            attributePoints[ii].origpercent /= length;
            attributePoints[ii].percent = attributePoints[ii].origpercent;
        }
    }

    if (closed) {
        QPointF end = path.currentPosition();
        *closed = length > 0 && startX == end.x() && startY == end.y();
    }
    pathLength = length;

    return path;
}

void QDeclarativePath::classBegin()
{
    Q_D(QDeclarativePath);
    d->componentComplete = false;
}

void QDeclarativePath::componentComplete()
{
    Q_D(QDeclarativePath);
    QSet<QString> attrs;
    d->componentComplete = true;

    // First gather up all the attributes
    foreach (QDeclarativePathElement *pathElement, d->_pathElements) {
        if (QDeclarativeCurve *curve =
            qobject_cast<QDeclarativeCurve *>(pathElement))
            d->_pathCurves.append(curve);
        else if (QDeclarativePathAttribute *attribute =
                 qobject_cast<QDeclarativePathAttribute *>(pathElement))
            attrs.insert(attribute->name());
    }
    d->_attributes = attrs.toList();

    processPath();

    foreach (QDeclarativePathElement *pathElement, d->_pathElements)
        connect(pathElement, SIGNAL(changed()), this, SLOT(processPath()));
}

QPainterPath QDeclarativePath::path() const
{
    Q_D(const QDeclarativePath);
    return d->_path;
}

QStringList QDeclarativePath::attributes() const
{
    Q_D(const QDeclarativePath);
    if (!d->componentComplete) {
        QSet<QString> attrs;

        // First gather up all the attributes
        foreach (QDeclarativePathElement *pathElement, d->_pathElements) {
            if (QDeclarativePathAttribute *attribute =
                qobject_cast<QDeclarativePathAttribute *>(pathElement))
                attrs.insert(attribute->name());
        }
        return attrs.toList();
    }
    return d->_attributes;
}

static inline QBezier nextBezier(const QPainterPath &path, int *current, qreal *bezLength, bool reverse = false)
{
    const int lastElement = reverse ? 0 : path.elementCount() - 1;
    const int start = reverse ? *current - 1 : *current + 1;
    for (int i=start; reverse ? i >= lastElement : i <= lastElement; reverse ? --i : ++i) {
        const QPainterPath::Element &e = path.elementAt(i);

        switch (e.type) {
        case QPainterPath::MoveToElement:
            break;
        case QPainterPath::LineToElement:
        {
            QLineF line(path.elementAt(i-1), e);
            *bezLength = line.length();
            QPointF a = path.elementAt(i-1);
            QPointF delta = e - a;
            *current = i;
            return QBezier::fromPoints(a, a + delta / 3, a + 2 * delta / 3, e);
        }
        case QPainterPath::CurveToElement:
        {
            QBezier b = QBezier::fromPoints(path.elementAt(i-1),
                                            e,
                                            path.elementAt(i+1),
                                            path.elementAt(i+2));
            *bezLength = b.length();
            *current = i;
            return b;
        }
        default:
            break;
        }
    }
    *current = lastElement;
    *bezLength = 0;
    return QBezier();
}

//derivative of the equation
static inline qreal slopeAt(qreal t, qreal a, qreal b, qreal c, qreal d)
{
    return 3*t*t*(d - 3*c + 3*b - a) + 6*t*(c - 2*b + a) + 3*(b - a);
}

void QDeclarativePath::createPointCache() const
{
    Q_D(const QDeclarativePath);
    qreal pathLength = d->pathLength;
    if (pathLength <= 0 || qIsNaN(pathLength))
        return;
    // more points means less jitter between items as they move along the
    // path, but takes longer to generate
    const int points = qCeil(pathLength*5);
    const int lastElement = d->_path.elementCount() - 1;
    d->_pointCache.resize(points+1);

    int currElement = -1;
    qreal bezLength = 0;
    QBezier currBez = nextBezier(d->_path, &currElement, &bezLength);
    qreal currLength = bezLength;
    qreal epc = currLength / pathLength;

    for (int i = 0; i < d->_pointCache.size(); i++) {
        //find which set we are in
        qreal prevPercent = 0;
        qreal prevOrigPercent = 0;
        for (int ii = 0; ii < d->_attributePoints.count(); ++ii) {
            qreal percent = qreal(i)/points;
            const AttributePoint &point = d->_attributePoints.at(ii);
            if (percent < point.percent || ii == d->_attributePoints.count() - 1) { //### || is special case for very last item
                qreal elementPercent = (percent - prevPercent);

                qreal spc = prevOrigPercent + elementPercent * point.scale;

                while (spc > epc) {
                    if (currElement > lastElement)
                        break;
                    currBez = nextBezier(d->_path, &currElement, &bezLength);
                    if (bezLength == 0.0) {
                        currLength = pathLength;
                        epc = 1.0;
                        break;
                    }
                    currLength += bezLength;
                    epc = currLength / pathLength;
                }
                qreal realT = (pathLength * spc - (currLength - bezLength)) / bezLength;
                d->_pointCache[i] = currBez.pointAt(qBound(qreal(0), realT, qreal(1)));
                break;
            }
            prevOrigPercent = point.origpercent;
            prevPercent = point.percent;
        }
    }
}

void QDeclarativePath::invalidateSequentialHistory() const
{
    Q_D(const QDeclarativePath);
    d->prevBez.isValid = false;
}

QPointF QDeclarativePath::sequentialPointAt(qreal p, qreal *angle) const
{
    Q_D(const QDeclarativePath);
    return sequentialPointAt(d->_path, d->pathLength, d->_attributePoints, d->prevBez, p, angle);
}

QPointF QDeclarativePath::sequentialPointAt(const QPainterPath &path, const qreal &pathLength, const QList<AttributePoint> &attributePoints, QDeclarativeCachedBezier &prevBez, qreal p, qreal *angle)
{
    if (!prevBez.isValid)
        return p > .5 ? backwardsPointAt(path, pathLength, attributePoints, prevBez, p, angle) :
                        forwardsPointAt(path, pathLength, attributePoints, prevBez, p, angle);

    return p < prevBez.p ? backwardsPointAt(path, pathLength, attributePoints, prevBez, p, angle) :
                           forwardsPointAt(path, pathLength, attributePoints, prevBez, p, angle);
}

QPointF QDeclarativePath::forwardsPointAt(const QPainterPath &path, const qreal &pathLength, const QList<AttributePoint> &attributePoints, QDeclarativeCachedBezier &prevBez, qreal p, qreal *angle)
{
    if (pathLength <= 0 || qIsNaN(pathLength))
        return path.pointAtPercent(0);  //expensive?

    const int lastElement = path.elementCount() - 1;
    bool haveCachedBez = prevBez.isValid;
    int currElement = haveCachedBez ? prevBez.element : -1;
    qreal bezLength = haveCachedBez ? prevBez.bezLength : 0;
    QBezier currBez = haveCachedBez ? prevBez.bezier : nextBezier(path, &currElement, &bezLength);
    qreal currLength = haveCachedBez ? prevBez.currLength : bezLength;
    qreal epc = currLength / pathLength;

    //find which set we are in
    qreal prevPercent = 0;
    qreal prevOrigPercent = 0;
    for (int ii = 0; ii < attributePoints.count(); ++ii) {
        qreal percent = p;
        const AttributePoint &point = attributePoints.at(ii);
        if (percent < point.percent || ii == attributePoints.count() - 1) {
            qreal elementPercent = (percent - prevPercent);

            qreal spc = prevOrigPercent + elementPercent * point.scale;

            while (spc > epc) {
                Q_ASSERT(!(currElement > lastElement));
                Q_UNUSED(lastElement);
                currBez = nextBezier(path, &currElement, &bezLength);
                currLength += bezLength;
                epc = currLength / pathLength;
            }
            prevBez.element = currElement;
            prevBez.bezLength = bezLength;
            prevBez.currLength = currLength;
            prevBez.bezier = currBez;
            prevBez.p = p;
            prevBez.isValid = true;

            qreal realT = (pathLength * spc - (currLength - bezLength)) / bezLength;

            if (angle) {
                qreal m1 = slopeAt(realT, currBez.x1, currBez.x2, currBez.x3, currBez.x4);
                qreal m2 = slopeAt(realT, currBez.y1, currBez.y2, currBez.y3, currBez.y4);
                *angle = QLineF(0, 0, m1, m2).angle();
            }

            return currBez.pointAt(qBound(qreal(0), realT, qreal(1)));
        }
        prevOrigPercent = point.origpercent;
        prevPercent = point.percent;
    }

    return QPointF(0,0);
}

//ideally this should be merged with forwardsPointAt
QPointF QDeclarativePath::backwardsPointAt(const QPainterPath &path, const qreal &pathLength, const QList<AttributePoint> &attributePoints, QDeclarativeCachedBezier &prevBez, qreal p, qreal *angle)
{
    if (pathLength <= 0 || qIsNaN(pathLength))
        return path.pointAtPercent(0);

    const int firstElement = 1; //element 0 is always a MoveTo, which we ignore
    bool haveCachedBez = prevBez.isValid;
    int currElement = haveCachedBez ? prevBez.element : path.elementCount();
    qreal bezLength = haveCachedBez ? prevBez.bezLength : 0;
    QBezier currBez = haveCachedBez ? prevBez.bezier : nextBezier(path, &currElement, &bezLength, true /*reverse*/);
    qreal currLength = haveCachedBez ? prevBez.currLength : pathLength;
    qreal prevLength = currLength - bezLength;
    qreal epc = prevLength / pathLength;

    for (int ii = attributePoints.count() - 1; ii > 0; --ii) {
        qreal percent = p;
        const AttributePoint &point = attributePoints.at(ii);
        const AttributePoint &prevPoint = attributePoints.at(ii-1);
        if (percent > prevPoint.percent || ii == 1) {
            qreal elementPercent = (percent - prevPoint.percent);

            qreal spc = prevPoint.origpercent + elementPercent * point.scale;

            while (spc < epc) {
                Q_ASSERT(!(currElement < firstElement));
                Q_UNUSED(firstElement);
                currBez = nextBezier(path, &currElement, &bezLength, true /*reverse*/);
                //special case for first element is to avoid floating point math
                //causing an epc that never hits 0.
                currLength = (currElement == firstElement) ? bezLength : prevLength;
                prevLength = currLength - bezLength;
                epc = prevLength / pathLength;
            }
            prevBez.element = currElement;
            prevBez.bezLength = bezLength;
            prevBez.currLength = currLength;
            prevBez.bezier = currBez;
            prevBez.p = p;
            prevBez.isValid = true;

            qreal realT = (pathLength * spc - (currLength - bezLength)) / bezLength;

            if (angle) {
                qreal m1 = slopeAt(realT, currBez.x1, currBez.x2, currBez.x3, currBez.x4);
                qreal m2 = slopeAt(realT, currBez.y1, currBez.y2, currBez.y3, currBez.y4);
                *angle = QLineF(0, 0, m1, m2).angle();
            }

            return currBez.pointAt(qBound(qreal(0), realT, qreal(1)));
        }
    }

    return QPointF(0,0);
}

QPointF QDeclarativePath::pointAt(qreal p) const
{
    Q_D(const QDeclarativePath);
    if (d->_pointCache.isEmpty()) {
        createPointCache();
        if (d->_pointCache.isEmpty())
            return QPointF();
    }

    const int pointCacheSize = d->_pointCache.size();
    qreal idxf = p*pointCacheSize;
    int idx1 = qFloor(idxf);
    qreal delta = idxf - idx1;
    if (idx1 >= pointCacheSize)
        idx1 = pointCacheSize - 1;
    else if (idx1 < 0)
        idx1 = 0;

    if (delta == 0.0)
        return d->_pointCache.at(idx1);

    // interpolate between the two points.
    int idx2 = qCeil(idxf);
    if (idx2 >= pointCacheSize)
        idx2 = pointCacheSize - 1;
    else if (idx2 < 0)
        idx2 = 0;

    QPointF p1 = d->_pointCache.at(idx1);
    QPointF p2 = d->_pointCache.at(idx2);
    QPointF pos = p1 * (1.0-delta) + p2 * delta;

    return pos;
}

qreal QDeclarativePath::attributeAt(const QString &name, qreal percent) const
{
    Q_D(const QDeclarativePath);
    if (percent < 0 || percent > 1)
        return 0;

    for (int ii = 0; ii < d->_attributePoints.count(); ++ii) {
        const AttributePoint &point = d->_attributePoints.at(ii);

        if (point.percent == percent) {
            return point.values.value(name);
        } else if (point.percent > percent) {
            qreal lastValue =
                ii?(d->_attributePoints.at(ii - 1).values.value(name)):0;
            qreal lastPercent =
                ii?(d->_attributePoints.at(ii - 1).percent):0;
            qreal curValue = point.values.value(name);
            qreal curPercent = point.percent;

            return lastValue + (curValue - lastValue) * (percent - lastPercent) / (curPercent - lastPercent);
        }
    }

    return 0;
}

/****************************************************************************/

qreal QDeclarativeCurve::x() const
{
    return _x.isNull ? 0 : _x.value;
}

void QDeclarativeCurve::setX(qreal x)
{
    if (_x.isNull || _x != x) {
        _x = x;
        emit xChanged();
        emit changed();
    }
}

bool QDeclarativeCurve::hasX()
{
    return _x.isValid();
}

qreal QDeclarativeCurve::y() const
{
    return _y.isNull ? 0 : _y.value;
}

void QDeclarativeCurve::setY(qreal y)
{
    if (_y.isNull || _y != y) {
        _y = y;
        emit yChanged();
        emit changed();
    }
}

bool QDeclarativeCurve::hasY()
{
    return _y.isValid();
}

qreal QDeclarativeCurve::relativeX() const
{
    return _relativeX;
}

void QDeclarativeCurve::setRelativeX(qreal x)
{
    if (_relativeX.isNull || _relativeX != x) {
        _relativeX = x;
        emit relativeXChanged();
        emit changed();
    }
}

bool QDeclarativeCurve::hasRelativeX()
{
    return _relativeX.isValid();
}

qreal QDeclarativeCurve::relativeY() const
{
    return _relativeY;
}

void QDeclarativeCurve::setRelativeY(qreal y)
{
    if (_relativeY.isNull || _relativeY != y) {
        _relativeY = y;
        emit relativeYChanged();
        emit changed();
    }
}

bool QDeclarativeCurve::hasRelativeY()
{
    return _relativeY.isValid();
}

/****************************************************************************/

/*!
    \qmlclass PathAttribute QDeclarativePathAttribute
    \inqmlmodule QtQuick 2
    \ingroup qml-view-elements
    \brief The PathAttribute allows setting an attribute at a given position in a Path.

    The PathAttribute object allows attributes consisting of a name and
    a value to be specified for various points along a path.  The
    attributes are exposed to the delegate as
    \l{qdeclarativeintroduction.html#attached-properties} {Attached Properties}.
    The value of an attribute at any particular point along the path is interpolated
    from the PathAttributes bounding that point.

    The example below shows a path with the items scaled to 30% with
    opacity 50% at the top of the path and scaled 100% with opacity
    100% at the bottom.  Note the use of the PathView.iconScale and
    PathView.iconOpacity attached properties to set the scale and opacity
    of the delegate.

    \table
    \row
    \o \image declarative-pathattribute.png
    \o
    \snippet doc/src/snippets/declarative/pathview/pathattributes.qml 0
    (see the PathView documentation for the specification of ContactModel.qml
     used for ContactModel above.)
    \endtable


    \sa Path
*/

/*!
    \qmlproperty string QtQuick2::PathAttribute::name
    This property holds the name of the attribute to change.

    This attribute will be available to the delegate as PathView.<name>

    Note that using an existing Item property name such as "opacity" as an
    attribute is allowed.  This is because path attributes add a new
    \l{qdeclarativeintroduction.html#attached-properties} {Attached Property}
    which in no way clashes with existing properties.
*/

/*!
    the name of the attribute to change.
*/

QString QDeclarativePathAttribute::name() const
{
    return _name;
}

void QDeclarativePathAttribute::setName(const QString &name)
{
    if (_name == name)
        return;
     _name = name;
    emit nameChanged();
}

/*!
   \qmlproperty real QtQuick2::PathAttribute::value
   This property holds the value for the attribute.

   The value specified can be used to influence the visual appearance
   of an item along the path. For example, the following Path specifies
   an attribute named \e itemRotation, which has the value \e 0 at the
   beginning of the path, and the value 90 at the end of the path.

   \qml
   Path {
       startX: 0
       startY: 0
       PathAttribute { name: "itemRotation"; value: 0 }
       PathLine { x: 100; y: 100 }
       PathAttribute { name: "itemRotation"; value: 90 }
   }
   \endqml

   In our delegate, we can then bind the \e rotation property to the
   \l{qdeclarativeintroduction.html#attached-properties} {Attached Property}
   \e PathView.itemRotation created for this attribute.

   \qml
   Rectangle {
       width: 10; height: 10
       rotation: PathView.itemRotation
   }
   \endqml

   As each item is positioned along the path, it will be rotated accordingly:
   an item at the beginning of the path with be not be rotated, an item at
   the end of the path will be rotated 90 degrees, and an item mid-way along
   the path will be rotated 45 degrees.
*/

/*!
    the new value of the attribute.
*/
qreal QDeclarativePathAttribute::value() const
{
    return _value;
}

void QDeclarativePathAttribute::setValue(qreal value)
{
    if (_value != value) {
        _value = value;
        emit valueChanged();
        emit changed();
    }
}

/****************************************************************************/

/*!
    \qmlclass PathLine QDeclarativePathLine
    \inqmlmodule QtQuick 2
    \ingroup qml-view-elements
    \brief The PathLine defines a straight line.

    The example below creates a path consisting of a straight line from
    0,100 to 200,100:

    \qml
    Path {
        startX: 0; startY: 100
        PathLine { x: 200; y: 100 }
    }
    \endqml

    \sa Path, PathQuad, PathCubic, PathArc, PathCurve, PathSvg
*/

/*!
    \qmlproperty real QtQuick2::PathLine::x
    \qmlproperty real QtQuick2::PathLine::y

    Defines the end point of the line.

    \sa relativeX, relativeY
*/

/*!
    \qmlproperty real QtQuick2::PathLine::relativeX
    \qmlproperty real QtQuick2::PathLine::relativeY

    Defines the end point of the line relative to its start.

    If both a relative and absolute end position are specified for a single axis, the relative
    position will be used.

    Relative and absolute positions can be mixed, for example it is valid to set a relative x
    and an absolute y.

    \sa x, y
*/

inline QPointF positionForCurve(const QDeclarativePathData &data, const QPointF &prevPoint)
{
    QDeclarativeCurve *curve = data.curves.at(data.index);
    bool isEnd = data.index == data.curves.size() - 1;
    return QPointF(curve->hasRelativeX() ? prevPoint.x() + curve->relativeX() : !isEnd || curve->hasX() ? curve->x() : data.endPoint.x(),
                   curve->hasRelativeY() ? prevPoint.y() + curve->relativeY() : !isEnd || curve->hasY() ? curve->y() : data.endPoint.y());
}

void QDeclarativePathLine::addToPath(QPainterPath &path, const QDeclarativePathData &data)
{
    path.lineTo(positionForCurve(data, path.currentPosition()));
}

/****************************************************************************/

/*!
    \qmlclass PathQuad QDeclarativePathQuad
    \inqmlmodule QtQuick 2
    \ingroup qml-view-elements
    \brief The PathQuad defines a quadratic Bezier curve with a control point.

    The following QML produces the path shown below:
    \table
    \row
    \o \image declarative-pathquad.png
    \o
    \qml
    Path {
        startX: 0; startY: 0
        PathQuad { x: 200; y: 0; controlX: 100; controlY: 150 }
    }
    \endqml
    \endtable

    \sa Path, PathCubic, PathLine, PathArc, PathCurve, PathSvg
*/

/*!
    \qmlproperty real QtQuick2::PathQuad::x
    \qmlproperty real QtQuick2::PathQuad::y

    Defines the end point of the curve.

    \sa relativeX, relativeY
*/

/*!
    \qmlproperty real QtQuick2::PathQuad::relativeX
    \qmlproperty real QtQuick2::PathQuad::relativeY

    Defines the end point of the curve relative to its start.

    If both a relative and absolute end position are specified for a single axis, the relative
    position will be used.

    Relative and absolute positions can be mixed, for example it is valid to set a relative x
    and an absolute y.

    \sa x, y
*/

/*!
   \qmlproperty real QtQuick2::PathQuad::controlX
   \qmlproperty real QtQuick2::PathQuad::controlY

   Defines the position of the control point.
*/

/*!
    the x position of the control point.
*/
qreal QDeclarativePathQuad::controlX() const
{
    return _controlX;
}

void QDeclarativePathQuad::setControlX(qreal x)
{
    if (_controlX != x) {
        _controlX = x;
        emit controlXChanged();
        emit changed();
    }
}


/*!
    the y position of the control point.
*/
qreal QDeclarativePathQuad::controlY() const
{
    return _controlY;
}

void QDeclarativePathQuad::setControlY(qreal y)
{
    if (_controlY != y) {
        _controlY = y;
        emit controlYChanged();
        emit changed();
    }
}

/*!
   \qmlproperty real QtQuick2::PathCubic::relativeControlX
   \qmlproperty real QtQuick2::PathCubic::relativeControlY

    Defines the position of the control point relative to the curve's start.

    If both a relative and absolute control position are specified for a single axis, the relative
    position will be used.

    Relative and absolute positions can be mixed, for example it is valid to set a relative control x
    and an absolute control y.

    \sa controlX, controlY
*/

qreal QDeclarativePathQuad::relativeControlX() const
{
    return _relativeControlX;
}

void QDeclarativePathQuad::setRelativeControlX(qreal x)
{
    if (_relativeControlX.isNull || _relativeControlX != x) {
        _relativeControlX = x;
        emit relativeControlXChanged();
        emit changed();
    }
}

bool QDeclarativePathQuad::hasRelativeControlX()
{
    return _relativeControlX.isValid();
}

qreal QDeclarativePathQuad::relativeControlY() const
{
    return _relativeControlY;
}

void QDeclarativePathQuad::setRelativeControlY(qreal y)
{
    if (_relativeControlY.isNull || _relativeControlY != y) {
        _relativeControlY = y;
        emit relativeControlYChanged();
        emit changed();
    }
}

bool QDeclarativePathQuad::hasRelativeControlY()
{
    return _relativeControlY.isValid();
}

void QDeclarativePathQuad::addToPath(QPainterPath &path, const QDeclarativePathData &data)
{
    const QPointF &prevPoint = path.currentPosition();
    QPointF controlPoint(hasRelativeControlX() ? prevPoint.x() + relativeControlX() : controlX(),
                         hasRelativeControlY() ? prevPoint.y() + relativeControlY() : controlY());
    path.quadTo(controlPoint, positionForCurve(data, path.currentPosition()));
}

/****************************************************************************/

/*!
   \qmlclass PathCubic QDeclarativePathCubic
    \inqmlmodule QtQuick 2
    \ingroup qml-view-elements
   \brief The PathCubic defines a cubic Bezier curve with two control points.

    The following QML produces the path shown below:
    \table
    \row
    \o \image declarative-pathcubic.png
    \o
    \qml
    Path {
        startX: 20; startY: 0
        PathCubic {
            x: 180; y: 0
            control1X: -10; control1Y: 90
            control2X: 210; control2Y: 90
        }
    }
    \endqml
    \endtable

    \sa Path, PathQuad, PathLine, PathArc, PathCurve, PathSvg
*/

/*!
    \qmlproperty real QtQuick2::PathCubic::x
    \qmlproperty real QtQuick2::PathCubic::y

    Defines the end point of the curve.

    \sa relativeX, relativeY
*/

/*!
    \qmlproperty real QtQuick2::PathCubic::relativeX
    \qmlproperty real QtQuick2::PathCubic::relativeY

    Defines the end point of the curve relative to its start.

    If both a relative and absolute end position are specified for a single axis, the relative
    position will be used.

    Relative and absolute positions can be mixed, for example it is valid to set a relative x
    and an absolute y.

    \sa x, y
*/

/*!
   \qmlproperty real QtQuick2::PathCubic::control1X
   \qmlproperty real QtQuick2::PathCubic::control1Y

    Defines the position of the first control point.
*/
qreal QDeclarativePathCubic::control1X() const
{
    return _control1X;
}

void QDeclarativePathCubic::setControl1X(qreal x)
{
    if (_control1X != x) {
        _control1X = x;
        emit control1XChanged();
        emit changed();
    }
}

qreal QDeclarativePathCubic::control1Y() const
{
    return _control1Y;
}

void QDeclarativePathCubic::setControl1Y(qreal y)
{
    if (_control1Y != y) {
        _control1Y = y;
        emit control1YChanged();
        emit changed();
    }
}

/*!
   \qmlproperty real QtQuick2::PathCubic::control2X
   \qmlproperty real QtQuick2::PathCubic::control2Y

    Defines the position of the second control point.
*/
qreal QDeclarativePathCubic::control2X() const
{
    return _control2X;
}

void QDeclarativePathCubic::setControl2X(qreal x)
{
    if (_control2X != x) {
        _control2X = x;
        emit control2XChanged();
        emit changed();
    }
}

qreal QDeclarativePathCubic::control2Y() const
{
    return _control2Y;
}

void QDeclarativePathCubic::setControl2Y(qreal y)
{
    if (_control2Y != y) {
        _control2Y = y;
        emit control2YChanged();
        emit changed();
    }
}

/*!
   \qmlproperty real QtQuick2::PathCubic::relativeControl1X
   \qmlproperty real QtQuick2::PathCubic::relativeControl1Y
   \qmlproperty real QtQuick2::PathCubic::relativeControl2X
   \qmlproperty real QtQuick2::PathCubic::relativeControl2Y

    Defines the positions of the control points relative to the curve's start.

    If both a relative and absolute control position are specified for a control point's axis, the relative
    position will be used.

    Relative and absolute positions can be mixed, for example it is valid to set a relative control1 x
    and an absolute control1 y.

    \sa control1X, control1Y, control2X, control2Y
*/

qreal QDeclarativePathCubic::relativeControl1X() const
{
    return _relativeControl1X;
}

void QDeclarativePathCubic::setRelativeControl1X(qreal x)
{
    if (_relativeControl1X.isNull || _relativeControl1X != x) {
        _relativeControl1X = x;
        emit relativeControl1XChanged();
        emit changed();
    }
}

bool QDeclarativePathCubic::hasRelativeControl1X()
{
    return _relativeControl1X.isValid();
}

qreal QDeclarativePathCubic::relativeControl1Y() const
{
    return _relativeControl1Y;
}

void QDeclarativePathCubic::setRelativeControl1Y(qreal y)
{
    if (_relativeControl1Y.isNull || _relativeControl1Y != y) {
        _relativeControl1Y = y;
        emit relativeControl1YChanged();
        emit changed();
    }
}

bool QDeclarativePathCubic::hasRelativeControl1Y()
{
    return _relativeControl1Y.isValid();
}

qreal QDeclarativePathCubic::relativeControl2X() const
{
    return _relativeControl2X;
}

void QDeclarativePathCubic::setRelativeControl2X(qreal x)
{
    if (_relativeControl2X.isNull || _relativeControl2X != x) {
        _relativeControl2X = x;
        emit relativeControl2XChanged();
        emit changed();
    }
}

bool QDeclarativePathCubic::hasRelativeControl2X()
{
    return _relativeControl2X.isValid();
}

qreal QDeclarativePathCubic::relativeControl2Y() const
{
    return _relativeControl2Y;
}

void QDeclarativePathCubic::setRelativeControl2Y(qreal y)
{
    if (_relativeControl2Y.isNull || _relativeControl2Y != y) {
        _relativeControl2Y = y;
        emit relativeControl2YChanged();
        emit changed();
    }
}

bool QDeclarativePathCubic::hasRelativeControl2Y()
{
    return _relativeControl2Y.isValid();
}

void QDeclarativePathCubic::addToPath(QPainterPath &path, const QDeclarativePathData &data)
{
    const QPointF &prevPoint = path.currentPosition();
    QPointF controlPoint1(hasRelativeControl1X() ? prevPoint.x() + relativeControl1X() : control1X(),
                          hasRelativeControl1Y() ? prevPoint.y() + relativeControl1Y() : control1Y());
    QPointF controlPoint2(hasRelativeControl2X() ? prevPoint.x() + relativeControl2X() : control2X(),
                          hasRelativeControl2Y() ? prevPoint.y() + relativeControl2Y() : control2Y());
    path.cubicTo(controlPoint1, controlPoint2, positionForCurve(data, path.currentPosition()));
}

/****************************************************************************/

/*!
    \qmlclass PathCurve QDeclarativePathCurve
    \inqmlmodule QtQuick 2
    \ingroup qml-view-elements
    \brief The PathCurve defines a point on a Catmull-Rom curve.

    PathCurve provides an easy way to specify a curve passing directly through a set of points.
    Typically multiple PathCurves are used in a series, as the following example demonstrates:

    \snippet doc/src/snippets/declarative/path/basiccurve.qml 0

    This example produces the following path (with the starting point and PathCurve points
    highlighted in red):

    \image declarative-pathcurve.png

    \sa Path, PathLine, PathQuad, PathCubic, PathArc, PathSvg
*/

/*!
    \qmlproperty real QtQuick2::PathCurve::x
    \qmlproperty real QtQuick2::PathCurve::y

    Defines the end point of the curve.

    \sa relativeX, relativeY
*/

/*!
    \qmlproperty real QtQuick2::PathCurve::relativeX
    \qmlproperty real QtQuick2::PathCurve::relativeY

    Defines the end point of the curve relative to its start.

    If both a relative and absolute end position are specified for a single axis, the relative
    position will be used.

    Relative and absolute positions can be mixed, for example it is valid to set a relative x
    and an absolute y.

    \sa x, y
*/

inline QPointF previousPathPosition(const QPainterPath &path)
{
    int count = path.elementCount();
    if (count < 1)
        return QPointF();

    int index = path.elementAt(count-1).type == QPainterPath::CurveToDataElement ? count - 4 : count - 2;
    return index > -1 ? QPointF(path.elementAt(index)) : path.pointAtPercent(0);
}

void QDeclarativePathCatmullRomCurve::addToPath(QPainterPath &path, const QDeclarativePathData &data)
{
    //here we convert catmull-rom spline to bezier for use in QPainterPath.
    //basic conversion algorithm:
    //  catmull-rom points * inverse bezier matrix * catmull-rom matrix = bezier points
    //each point in the catmull-rom spline produces a bezier endpoint + 2 control points
    //calculations for each point use a moving window of 4 points
    //  (previous 2 points + current point + next point)
    QPointF prevFar, prev, point, next;

    //get previous points
    int index = data.index - 1;
    QDeclarativeCurve *curve = index == -1 ? 0 : data.curves.at(index);
    if (qobject_cast<QDeclarativePathCatmullRomCurve*>(curve)) {
        prev = path.currentPosition();
        prevFar = previousPathPosition(path);
    } else {
        prev = path.currentPosition();
        bool prevFarSet = false;
        if (index == -1 && data.curves.count() > 1) {
            if (qobject_cast<QDeclarativePathCatmullRomCurve*>(data.curves.at(data.curves.count()-1))) {
                //TODO: profile and optimize
                QPointF pos = prev;
                QDeclarativePathData loopData;
                loopData.endPoint = data.endPoint;
                loopData.curves = data.curves;
                for (int i = data.index; i < data.curves.count(); ++i) {
                    loopData.index = i;
                    pos = positionForCurve(loopData, pos);
                    if (i == data.curves.count()-2)
                        prevFar = pos;
                }
                if (pos == QPointF(path.elementAt(0))) {
                    //this is a closed path starting and ending with catmull-rom segments.
                    //we try to smooth the join point
                    prevFarSet = true;
                }
            }
        }
        if (!prevFarSet)
            prevFar = prev;
    }

    //get current point
    point = positionForCurve(data, path.currentPosition());

    //get next point
    index = data.index + 1;
    if (index < data.curves.count() && qobject_cast<QDeclarativePathCatmullRomCurve*>(data.curves.at(index))) {
        QDeclarativePathData nextData;
        nextData.index = index;
        nextData.endPoint = data.endPoint;
        nextData.curves = data.curves;
        next = positionForCurve(nextData, point);
    } else {
        if (point == QPointF(path.elementAt(0)) && qobject_cast<QDeclarativePathCatmullRomCurve*>(data.curves.at(0))) {
            //this is a closed path starting and ending with catmull-rom segments.
            //we try to smooth the join point
            next = QPointF(path.elementAt(3));  //the first catmull-rom point
        } else
            next = point;
    }

    /*
        full conversion matrix (inverse bezier * catmull-rom):
        0.000,  1.000,  0.000,  0.000,
        -0.167,  1.000,  0.167,  0.000,
        0.000,  0.167,  1.000, -0.167,
        0.000,  0.000,  1.000,  0.000

        conversion doesn't require full matrix multiplication,
        so below we simplify
    */
    QPointF control1(prevFar.x() * qreal(-0.167) +
                     prev.x() +
                     point.x() * qreal(0.167),
                     prevFar.y() * qreal(-0.167) +
                     prev.y() +
                     point.y() * qreal(0.167));

    QPointF control2(prev.x() * qreal(0.167) +
                     point.x() +
                     next.x() * qreal(-0.167),
                     prev.y() * qreal(0.167) +
                     point.y() +
                     next.y() * qreal(-0.167));

    path.cubicTo(control1, control2, point);
}

/****************************************************************************/

/*!
    \qmlclass PathArc QDeclarativePathArc
    \inqmlmodule QtQuick 2
    \ingroup qml-view-elements
    \brief The PathArc defines an arc with the given radius.

    PathArc provides a simple way of specifying an arc that ends at a given position
    and uses the specified radius. It is modeled after the SVG elliptical arc command.

    The following QML produces the path shown below:
    \table
    \row
    \o \image declarative-patharc.png
    \o \snippet doc/src/snippets/declarative/path/basicarc.qml 0
    \endtable

    Note that a single PathArc cannot be used to specify a circle. Instead, you can
    use two PathArc elements, each specifying half of the circle.

    \sa Path, PathLine, PathQuad, PathCubic, PathCurve, PathSvg
*/

/*!
    \qmlproperty real QtQuick2::PathArc::x
    \qmlproperty real QtQuick2::PathArc::y

    Defines the end point of the arc.

    \sa relativeX, relativeY
*/

/*!
    \qmlproperty real QtQuick2::PathArc::relativeX
    \qmlproperty real QtQuick2::PathArc::relativeY

    Defines the end point of the arc relative to its start.

    If both a relative and absolute end position are specified for a single axis, the relative
    position will be used.

    Relative and absolute positions can be mixed, for example it is valid to set a relative x
    and an absolute y.

    \sa x, y
*/

/*!
    \qmlproperty real QtQuick2::PathArc::radiusX
    \qmlproperty real QtQuick2::PathArc::radiusY

    Defines the radius of the arc.

    The following QML demonstrates how different radius values can be used to change
    the shape of the arc:
    \table
    \row
    \o \image declarative-arcradius.png
    \o \snippet doc/src/snippets/declarative/path/arcradius.qml 0
    \endtable
*/

qreal QDeclarativePathArc::radiusX() const
{
    return _radiusX;
}

void QDeclarativePathArc::setRadiusX(qreal radius)
{
    if (_radiusX == radius)
        return;

    _radiusX = radius;
    emit radiusXChanged();
}

qreal QDeclarativePathArc::radiusY() const
{
    return _radiusY;
}

void QDeclarativePathArc::setRadiusY(qreal radius)
{
    if (_radiusY == radius)
        return;

    _radiusY = radius;
    emit radiusYChanged();
}

/*!
    \qmlproperty bool QtQuick2::PathArc::useLargeArc
    Whether to use a large arc as defined by the arc points.

    Given fixed start and end positions, radius, and direction,
    there are two possible arcs that can fit the data. useLargeArc
    is used to distinguish between these. For example, the following
    QML can produce either of the two illustrated arcs below by
    changing the value of useLargeArc.

    \table
    \row
    \o \image declarative-largearc.png
    \o \snippet doc/src/snippets/declarative/path/largearc.qml 0
    \endtable

    The default value is false.
*/

bool QDeclarativePathArc::useLargeArc() const
{
    return _useLargeArc;
}

void QDeclarativePathArc::setUseLargeArc(bool largeArc)
{
    if (_useLargeArc == largeArc)
        return;

    _useLargeArc = largeArc;
    emit useLargeArcChanged();
}

/*!
    \qmlproperty enum QtQuick2::PathArc::direction

    Defines the direction of the arc. Possible values are
    PathArc.Clockwise (default) and PathArc.Counterclockwise.

    The following QML can produce either of the two illustrated arcs below
    by changing the value of direction.
    \table
    \row
    \o \image declarative-arcdirection.png
    \o \snippet doc/src/snippets/declarative/path/arcdirection.qml 0
    \endtable

    \sa useLargeArc
*/

QDeclarativePathArc::ArcDirection QDeclarativePathArc::direction() const
{
    return _direction;
}

void QDeclarativePathArc::setDirection(ArcDirection direction)
{
    if (_direction == direction)
        return;

    _direction = direction;
    emit directionChanged();
}

void QDeclarativePathArc::addToPath(QPainterPath &path, const QDeclarativePathData &data)
{
    const QPointF &startPoint = path.currentPosition();
    const QPointF &endPoint = positionForCurve(data, startPoint);
    QDeclarativeSvgParser::pathArc(path,
            _radiusX,
            _radiusY,
            0,  //xAxisRotation
            _useLargeArc,
            _direction == Clockwise ? 1 : 0,
            endPoint.x(),
            endPoint.y(),
            startPoint.x(), startPoint.y());
}

/****************************************************************************/

/*!
    \qmlclass PathSvg QDeclarativePathSvg
    \inqmlmodule QtQuick 2
    \ingroup qml-view-elements
    \brief The PathSvg defines a path using an SVG path data string.

    The following QML produces the path shown below:
    \table
    \row
    \o \image declarative-pathsvg.png
    \o
    \qml
    Path {
        startX: 50; startY: 50
        PathSvg { path: "L 150 50 L 100 150 z" }
    }
    \endqml
    \endtable

    \sa Path, PathLine, PathQuad, PathCubic, PathArc, PathCurve
*/

/*!
    \qmlproperty string QtQuick2::PathSvg::path

    The SVG path data string specifying the path.

    See \l {http://www.w3.org/TR/SVG/paths.html#PathData}{W3C SVG Path Data}
    for more details on this format.
*/

QString QDeclarativePathSvg::path() const
{
    return _path;
}

void QDeclarativePathSvg::setPath(const QString &path)
{
    if (_path == path)
        return;

    _path = path;
    emit pathChanged();
}

void QDeclarativePathSvg::addToPath(QPainterPath &path, const QDeclarativePathData &)
{
    QDeclarativeSvgParser::parsePathDataFast(_path, path);
}

/****************************************************************************/

/*!
    \qmlclass PathPercent QDeclarativePathPercent
    \inqmlmodule QtQuick 2
    \ingroup qml-view-elements
    \brief The PathPercent manipulates the way a path is interpreted.

    PathPercent allows you to manipulate the spacing between items on a
    PathView's path. You can use it to bunch together items on part of
    the path, and spread them out on other parts of the path.

    The examples below show the normal distribution of items along a path
    compared to a distribution which places 50% of the items along the
    PathLine section of the path.
    \table
    \row
    \o \image declarative-nopercent.png
    \o
    \qml
    PathView {
        // ...
        Path {
            startX: 20; startY: 0
            PathQuad { x: 50; y: 80; controlX: 0; controlY: 80 }
            PathLine { x: 150; y: 80 }
            PathQuad { x: 180; y: 0; controlX: 200; controlY: 80 }
        }
    }
    \endqml
    \row
    \o \image declarative-percent.png
    \o
    \qml
    PathView {
        // ...
        Path {
            startX: 20; startY: 0
            PathQuad { x: 50; y: 80; controlX: 0; controlY: 80 }
            PathPercent { value: 0.25 }
            PathLine { x: 150; y: 80 }
            PathPercent { value: 0.75 }
            PathQuad { x: 180; y: 0; controlX: 200; controlY: 80 }
            PathPercent { value: 1 }
        }
    }
    \endqml
    \endtable

    \sa Path
*/

/*!
    \qmlproperty real QtQuick2::PathPercent::value
    The proportion of items that should be laid out up to this point.

    This value should always be higher than the last value specified
    by a PathPercent at a previous position in the Path.

    In the following example we have a Path made up of three PathLines.
    Normally, the items of the PathView would be laid out equally along
    this path, with an equal number of items per line segment. PathPercent
    allows us to specify that the first and third lines should each hold
    10% of the laid out items, while the second line should hold the remaining
    80%.

    \qml
    PathView {
        // ...
        Path {
            startX: 0; startY: 0
            PathLine { x:100; y: 0; }
            PathPercent { value: 0.1 }
            PathLine { x: 100; y: 100 }
            PathPercent { value: 0.9 }
            PathLine { x: 100; y: 0 }
            PathPercent { value: 1 }
        }
    }
    \endqml
*/

qreal QDeclarativePathPercent::value() const
{
    return _value;
}

void QDeclarativePathPercent::setValue(qreal value)
{
    if (_value != value) {
        _value = value;
        emit valueChanged();
        emit changed();
    }
}
QT_END_NAMESPACE