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#include "private/qdeclarativeflipable_p.h"

#include "private/qdeclarativeitem_p.h"

#include "private/qdeclarativeguard_p.h"

#include <qdeclarativeinfo.h>

#include <QtGui/qgraphicstransform.h>

QT_BEGIN_NAMESPACE

class QDeclarativeFlipablePrivate : public QDeclarativeItemPrivate

{

    Q_DECLARE_PUBLIC(QDeclarativeFlipable)

public:

    QDeclarativeFlipablePrivate() : current(QDeclarativeFlipable::Front), front(0), back(0) {}

    void updateSceneTransformFromParent();

    void setBackTransform();

    QDeclarativeFlipable::Side current;

    QDeclarativeGuard<QGraphicsObject> front;

    QDeclarativeGuard<QGraphicsObject> back;

    bool wantBackXFlipped;

    bool wantBackYFlipped;

};

/*!

    \qmlclass Flipable QDeclarativeFlipable

    \since 4.7

    \brief The Flipable item provides a surface that can be flipped.

    \inherits Item

    Flipable is an item that can be visibly "flipped" between its front and

    produce a flipping effect.

    Here is a Flipable that flips whenever it is clicked:

    \snippet doc/src/snippets/declarative/flipable.qml 0

    \image flipable.gif

    angle over one second.

*/

/*!

    \internal

    \class QDeclarativeFlipable

    \brief The Flipable item provides a surface that can be flipped.

    Flipable is an item that can be visibly "flipped" between its front and

    back sides.

*/

QDeclarativeFlipable::QDeclarativeFlipable(QDeclarativeItem *parent)

: QDeclarativeItem(*(new QDeclarativeFlipablePrivate), parent)

{

}

QDeclarativeFlipable::~QDeclarativeFlipable()

{

}

/*!

  \qmlproperty Item Flipable::front

  \qmlproperty Item Flipable::back

  The front and back sides of the flipable.

*/

QGraphicsObject *QDeclarativeFlipable::front()

{

    Q_D(const QDeclarativeFlipable);

    return d->front;

}

void QDeclarativeFlipable::setFront(QGraphicsObject *front)

{

    Q_D(QDeclarativeFlipable);

    if (d->front) {

        qmlInfo(this) << tr("front is a write-once property");

        return;

    }

    d->front = front;

    d->front->setParentItem(this);

    if (Back == d->current)

        d->front->setOpacity(0.);

}

QGraphicsObject *QDeclarativeFlipable::back()

{

    Q_D(const QDeclarativeFlipable);

    return d->back;

}

void QDeclarativeFlipable::setBack(QGraphicsObject *back)

{

    Q_D(QDeclarativeFlipable);

    if (d->back) {

        qmlInfo(this) << tr("back is a write-once property");

        return;

    }

    d->back = back;

    d->back->setParentItem(this);

    if (Front == d->current)

        d->back->setOpacity(0.);

    connect(back, SIGNAL(widthChanged()),

            this, SLOT(retransformBack()));

    connect(back, SIGNAL(heightChanged()),

            this, SLOT(retransformBack()));

}

void QDeclarativeFlipable::retransformBack()

{

    Q_D(QDeclarativeFlipable);

    if (d->current == QDeclarativeFlipable::Back && d->back)

        d->setBackTransform();

}

/*!

  \qmlproperty enumeration Flipable::side

  The side of the Flippable currently visible. Possible values are \c

  Flippable.Front and \c Flippable.Back.

*/

QDeclarativeFlipable::Side QDeclarativeFlipable::side() const

{

    Q_D(const QDeclarativeFlipable);

    if (d->dirtySceneTransform)

        const_cast<QDeclarativeFlipablePrivate *>(d)->ensureSceneTransform();

    return d->current;

}

// determination on the currently visible side of the flipable

// has to be done on the complete scene transform to give

// correct results.

void QDeclarativeFlipablePrivate::updateSceneTransformFromParent()

{

    Q_Q(QDeclarativeFlipable);

    QDeclarativeItemPrivate::updateSceneTransformFromParent();

    QPointF p1(0, 0);

    QPointF p2(1, 0);

    QPointF p3(1, 1);

    QPointF scenep1 = sceneTransform.map(p1);

    QPointF scenep2 = sceneTransform.map(p2);

    QPointF scenep3 = sceneTransform.map(p3);

    p1 = q->mapToParent(p1);

    p2 = q->mapToParent(p2);

    p3 = q->mapToParent(p3);

    qreal cross = (scenep1.x() - scenep2.x()) * (scenep3.y() - scenep2.y()) -

                  (scenep1.y() - scenep2.y()) * (scenep3.x() - scenep2.x());

    wantBackYFlipped = p1.x() >= p2.x();

    wantBackXFlipped = p2.y() >= p3.y();

    QDeclarativeFlipable::Side newSide;

    if (cross > 0) {

        newSide = QDeclarativeFlipable::Back;

    } else {

        newSide = QDeclarativeFlipable::Front;

    }

    if (newSide != current) {

        current = newSide;

        if (current == QDeclarativeFlipable::Back && back)

            setBackTransform();

        if (front)

            front->setOpacity((current==QDeclarativeFlipable::Front)?1.:0.);

        if (back)

            back->setOpacity((current==QDeclarativeFlipable::Back)?1.:0.);

        emit q->sideChanged();

    }

}

/* Depends on the width/height of the back item, and so needs reevaulating

   if those change.

*/

void QDeclarativeFlipablePrivate::setBackTransform()

{

    QTransform mat;

    QGraphicsItemPrivate *dBack = QGraphicsItemPrivate::get(back);

    mat.translate(dBack->width()/2,dBack->height()/2);

    if (dBack->width() && wantBackYFlipped)

        mat.rotate(180, Qt::YAxis);

    if (dBack->height() && wantBackXFlipped)

        mat.rotate(180, Qt::XAxis);

    mat.translate(-dBack->width()/2,-dBack->height()/2);

    back->setTransform(mat);

}

QT_END_NAMESPACE