path: root/src/declarative/graphicsitems/qmlgraphicspath.cpp

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#include "qmlgraphicspath_p.h"
#include "qmlgraphicspath_p_p.h"

#include <qfxperf_p_p.h>

#include <QSet>

#include <private/qbezier_p.h>

QT_BEGIN_NAMESPACE

/*!
    \qmlclass PathElement QmlGraphicsPathElement
    \since 4.7
    \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
*/

/*!
    \internal
    \class QmlGraphicsPathElement
    \ingroup group_utility
*/

/*!
    \qmlclass Path QmlGraphicsPath
    \since 4.7
    \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.

    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
*/

/*!
    \internal
    \class QmlGraphicsPath
    \ingroup group_utility
    \brief The QmlGraphicsPath class defines a path.
    \sa QmlGraphicsPathView
*/
QmlGraphicsPath::QmlGraphicsPath(QObject *parent)
 : QObject(*(new QmlGraphicsPathPrivate), parent)
{
}

QmlGraphicsPath::~QmlGraphicsPath()
{
}

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

void QmlGraphicsPath::setStartX(qreal x)
{
    Q_D(QmlGraphicsPath);
    d->startX = x;
}

qreal QmlGraphicsPath::startY() const
{
    Q_D(const QmlGraphicsPath);
    return d->startY;
}

void QmlGraphicsPath::setStartY(qreal y)
{
    Q_D(QmlGraphicsPath);
    d->startY = y;
}

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

/*!
    \qmlproperty list<PathElement> 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 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
*/

QmlListProperty<QmlGraphicsPathElement> QmlGraphicsPath::pathElements()
{
    Q_D(QmlGraphicsPath);
    return QmlListProperty<QmlGraphicsPathElement>(this, d->_pathElements);
}

void QmlGraphicsPath::interpolate(int idx, const QString &name, qreal value)
{
    Q_D(QmlGraphicsPath);
    if (!idx)
        return;

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

    ++search;

    const AttributePoint &curPoint = d->_attributePoints.at(idx);

    for (int ii = search; ii < idx; ++ii) {
        AttributePoint &point = d->_attributePoints[ii];

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

void QmlGraphicsPath::endpoint(const QString &name)
{
    Q_D(QmlGraphicsPath);
    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 QmlGraphicsPath::processPath()
{
    Q_D(QmlGraphicsPath);

    d->_pointCache.clear();
    d->_attributePoints.clear();
    d->_path = QPainterPath();

    AttributePoint first;
    for (int ii = 0; ii < d->_attributes.count(); ++ii)
        first.values[d->_attributes.at(ii)] = 0;
    d->_attributePoints << first;

    d->_path.moveTo(d->startX, d->startY);

    QmlGraphicsCurve *lastCurve = 0;
    foreach (QmlGraphicsPathElement *pathElement, d->_pathElements) {
        if (QmlGraphicsCurve *curve = qobject_cast<QmlGraphicsCurve *>(pathElement)) {
            curve->addToPath(d->_path);
            AttributePoint p;
            p.origpercent = d->_path.length();
            d->_attributePoints << p;
            lastCurve = curve;
        } else if (QmlGraphicsPathAttribute *attribute = qobject_cast<QmlGraphicsPathAttribute *>(pathElement)) {
            AttributePoint &point = d->_attributePoints.last();
            point.values[attribute->name()] = attribute->value();
            interpolate(d->_attributePoints.count() - 1, attribute->name(), attribute->value());
        } else if (QmlGraphicsPathPercent *percent = qobject_cast<QmlGraphicsPathPercent *>(pathElement)) {
            AttributePoint &point = d->_attributePoints.last();
            point.values[QLatin1String("_qfx_percent")] = percent->value();
            interpolate(d->_attributePoints.count() - 1, QLatin1String("_qfx_percent"), percent->value());
        }
    }

    // Fixup end points
    const AttributePoint &last = d->_attributePoints.last();
    for (int ii = 0; ii < d->_attributes.count(); ++ii) {
        if (!last.values.contains(d->_attributes.at(ii)))
            endpoint(d->_attributes.at(ii));
    }

    // Adjust percent
    qreal length = d->_path.length();
    qreal prevpercent = 0;
    qreal prevorigpercent = 0;
    for (int ii = 0; ii < d->_attributePoints.count(); ++ii) {
        const AttributePoint &point = d->_attributePoints.at(ii);
        if (point.values.contains(QLatin1String("_qfx_percent"))) { //special string for QmlGraphicsPathPercent
            if ( ii > 0) {
                qreal scale = (d->_attributePoints[ii].origpercent/length - prevorigpercent) /
                            (point.values.value(QLatin1String("_qfx_percent"))-prevpercent);
                d->_attributePoints[ii].scale = scale;
            }
            d->_attributePoints[ii].origpercent /= length;
            d->_attributePoints[ii].percent = point.values.value(QLatin1String("_qfx_percent"));
            prevorigpercent = d->_attributePoints[ii].origpercent;
            prevpercent = d->_attributePoints[ii].percent;
        } else {
            d->_attributePoints[ii].origpercent /= length;
            d->_attributePoints[ii].percent = d->_attributePoints[ii].origpercent;
        }
    }

    d->closed = lastCurve && d->startX == lastCurve->x() && d->startY == lastCurve->y();

    emit changed();
}

void QmlGraphicsPath::componentComplete()
{
    Q_D(QmlGraphicsPath);
    QSet<QString> attrs;
    // First gather up all the attributes
    foreach (QmlGraphicsPathElement *pathElement, d->_pathElements) {
        if (QmlGraphicsPathAttribute *attribute =
            qobject_cast<QmlGraphicsPathAttribute *>(pathElement))
            attrs.insert(attribute->name());
    }
    d->_attributes = attrs.toList();

    processPath();

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

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

QStringList QmlGraphicsPath::attributes() const
{
    Q_D(const QmlGraphicsPath);
    return d->_attributes;
}
#include <QTime>

static inline QBezier nextBezier(const QPainterPath &path, int *from, qreal *bezLength)
{
    const int lastElement = path.elementCount() - 1;
    for (int i=*from; i <= lastElement; ++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;
            *from = i+1;
            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();
            *from = i+3;
            return b;
        }
        default:
            break;
        }
    }
    *from = lastElement;
    *bezLength = 0;
    return QBezier();
}

void QmlGraphicsPath::createPointCache() const
{
    Q_D(const QmlGraphicsPath);
#ifdef Q_ENABLE_PERFORMANCE_LOG
    QmlPerfTimer<QmlPerf::QmlGraphicsPathViewPathCache> pc;
#endif
    qreal pathLength = d->_path.length();
    const int points = int(pathLength*2);
    const int lastElement = d->_path.elementCount() - 1;
    d->_pointCache.resize(points+1);

    int currElement = 0;
    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;
        }
    }
}

QPointF QmlGraphicsPath::pointAt(qreal p) const
{
    Q_D(const QmlGraphicsPath);
    if (d->_pointCache.isEmpty()) {
        createPointCache();
    }
    int idx = qRound(p*d->_pointCache.size());
    if (idx >= d->_pointCache.size())
        idx = d->_pointCache.size() - 1;
    else if (idx < 0)
        idx = 0;
    return d->_pointCache.at(idx);
}

qreal QmlGraphicsPath::attributeAt(const QString &name, qreal percent) const
{
    Q_D(const QmlGraphicsPath);
    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 QmlGraphicsCurve::x() const
{
    return _x;
}

void QmlGraphicsCurve::setX(qreal x)
{
    if (_x != x) {
        _x = x;
        emit changed();
    }
}

qreal QmlGraphicsCurve::y() const
{
    return _y;
}

void QmlGraphicsCurve::setY(qreal y)
{
    if (_y != y) {
        _y = y;
        emit changed();
    }
}

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

/*!
    \qmlclass PathAttribute QmlGraphicsPathAttribute
    \since 4.7
    \brief The PathAttribute allows setting an attribute at a given position in a Path.

    The PathAttribute object allows attibutes consisting of a name and
    a value to be specified for the endpoints of path segments.  The
    attributes are exposed to the delegate as
    \l{qmlintroduction.html#attached-properties} {Attached Properties}.
    The value of an attribute at any particular point is interpolated
    from the PathAttributes bounding the 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.scale and
    PathView.opacity 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
    \endtable

   \sa Path
*/

/*!
    \internal
    \class QmlGraphicsPathAttribute
    \ingroup group_utility
    \brief The QmlGraphicsPathAttribute class allows to set the value of an attribute at a given position in the path.

    \sa QmlGraphicsPath
*/


/*!
    \qmlproperty string PathAttribute::name
    the name of the attribute to change.
*/

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

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

void QmlGraphicsPathAttribute::setName(const QString &name)
{
    _name = name;
}

/*!
   \qmlproperty string PathAttribute::value
   the new value of the attribute.
*/

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

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

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

/*!
    \qmlclass PathLine QmlGraphicsPathLine
    \since 4.7
    \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
*/

/*!
    \internal
    \class QmlGraphicsPathLine
    \ingroup group_utility
    \brief The QmlGraphicsPathLine class defines a straight line.

    \sa QmlGraphicsPath
*/

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

    Defines the end point of the line.
*/

void QmlGraphicsPathLine::addToPath(QPainterPath &path)
{
    path.lineTo(x(), y());
}

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

/*!
    \qmlclass PathQuad QmlGraphicsPathQuad
    \since 4.7
    \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
*/

/*!
    \internal
    \class QmlGraphicsPathQuad
    \ingroup group_utility
    \brief The QmlGraphicsPathQuad class defines a quadratic Bezier curve with a control point.

    \sa QmlGraphicsPath
*/


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

    Defines the end point of the curve.
*/

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

   Defines the position of the control point.
*/

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

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


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

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

void QmlGraphicsPathQuad::addToPath(QPainterPath &path)
{
    path.quadTo(controlX(), controlY(), x(), y());
}

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

/*!
   \qmlclass PathCubic QmlGraphicsPathCubic
    \since 4.7
   \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
*/

/*!
    \internal
    \class QmlGraphicsPathCubic
    \ingroup group_utility
    \brief The QmlGraphicsPathCubic class defines a cubic Bezier curve with two control points.

    \sa QmlGraphicsPath
*/

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

    Defines the end point of the curve.
*/

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

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

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

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

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

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

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

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

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

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

void QmlGraphicsPathCubic::addToPath(QPainterPath &path)
{
    path.cubicTo(control1X(), control1Y(), control2X(), control2Y(), x(), y());
}

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

/*!
    \qmlclass PathPercent QmlGraphicsPathPercent
    \since 4.7
    \brief The PathPercent manipulates the way a path is interpreted.

    The examples below show the normal distrubution 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
    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
    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
*/

/*!
    \internal
    \class QmlGraphicsPathPercent
    \ingroup group_utility
    \brief The QmlGraphicsPathPercent class manipulates the way a path is interpreted.

    QmlGraphicsPathPercent allows you to bunch up items (or spread out items) along various
    segments of a QmlGraphicsPathView's path.

    \sa QmlGraphicsPath

*/

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

void QmlGraphicsPathPercent::setValue(qreal value)
{
    _value = value;
}
QT_END_NAMESPACE