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**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
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**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the Technology Preview License Agreement accompanying
** this package.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
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#include <QApplication>
#include <QGraphicsRotation>
#include <QPropertyAnimation>
#include <QGraphicsLinearLayout>
#include <QParallelAnimationGroup>
#include <QGraphicsSceneResizeEvent>

#include "dataresource.h"
#include "view.h"
#include "button.h"
#include "pagemenu.h"
#include "pageview.h"

// XXX: adjust to false when opengl is available
#define USE_LINEAR_TRANSITION true


class PageSlot : public QGraphicsWidget
{
    Q_OBJECT
    Q_PROPERTY(qreal pageSlide READ pageSlide WRITE setPageSlide);

public:
    enum MovementType {
        MoveInLeft,
        MoveInRight,
        MoveOutLeft,
        MoveOutRight
    };

    PageSlot(QGraphicsItem *parent = 0);

    qreal pageSlide() const;
    void setPageSlide(qreal percent);

    View *contents() const;
    void setContents(View *contents);

    QAbstractAnimation *createAnimation(MovementType type);

protected:
    void resizeEvent(QGraphicsSceneResizeEvent *event);

private:
    bool m_isOut;
    bool m_isLeft;
    qreal m_pageSlide;
    bool m_isLinearTransition;
    View *m_contents;
    QGraphicsRotation *m_rotation;
};


PageSlot::PageSlot(QGraphicsItem *parent)
    : QGraphicsWidget(parent),
      m_contents(0),
      m_rotation(new QGraphicsRotation(this))
{
    setFlags(QGraphicsItem::ItemHasNoContents);

#ifdef Q_OS_SYMBIAN
    m_isLinearTransition = true;
#else
    m_isLinearTransition = USE_LINEAR_TRANSITION;
#endif

    m_rotation->setAxis(Qt::YAxis);

    QList<QGraphicsTransform*> transforms;
    transforms.append(m_rotation);
    setTransformations(transforms);
}

qreal PageSlot::pageSlide() const
{
    return m_pageSlide;
}

void PageSlot::setPageSlide(qreal percent)
{
    m_pageSlide = percent;

    if (!m_isLinearTransition) {
        // apply flip values
        const qreal np = m_isOut ? percent : (1 - percent);
        m_rotation->setAngle((m_isLeft ? 180 : -180) * np);
    } else {
        // apply linear pos values
        const int sw = size().width();
        const qreal sx = (m_isLeft ? -sw : sw);
        setX(sx * (m_isOut ? percent : 1 - percent));
    }
}

View *PageSlot::contents() const
{
    return m_contents;
}

void PageSlot::setContents(View *contents)
{
    if (m_contents && m_contents->parentItem() == this)
        m_contents->setParentItem(0);

    m_contents = contents;

    if (contents) {
        contents->setParentItem(this);
        contents->setGeometry(0, 0, size().width(), size().height());
    }
}

QAbstractAnimation *PageSlot::createAnimation(MovementType type)
{
    m_isOut = (type == MoveOutLeft || type == MoveOutRight);
    m_isLeft = (type == MoveInLeft || type == MoveOutLeft);

    if (!m_isLinearTransition) {
        QVector3D ov(m_isLeft ? 0 : size().width(), 0, 0);
        m_rotation->setOrigin(ov);
    }

    QPropertyAnimation *animation = new QPropertyAnimation(this, "pageSlide");
    animation->setDuration(500);
    animation->setEasingCurve(QEasingCurve::OutQuart);
    animation->setStartValue(0.0);
    animation->setEndValue(1.0);

    return animation;
}

void PageSlot::resizeEvent(QGraphicsSceneResizeEvent *event)
{
    QGraphicsWidget::resizeEvent(event);

    if (m_contents)
        m_contents->resize(event->newSize());
}


PageView::PageView(QGraphicsItem *parent)
    : QGraphicsWidget(parent),
      m_isBack(false)
{
    m_topOffset = Resource::intValue("page-view/margin-top");

    setFlag(QGraphicsItem::ItemHasNoContents);

    QGraphicsLinearLayout *layout = new QGraphicsLinearLayout(Qt::Vertical);
    layout->setContentsMargins(20, 40, 20, 0);

    QGraphicsLinearLayout *topLayout = new QGraphicsLinearLayout(Qt::Horizontal);
    topLayout->setContentsMargins(0, 0, 0, 0);

    setLayout(layout);
    layout->addItem(topLayout);
    layout->addStretch(1);

    m_menu = new PageMenu();

    m_backButton = new Button(Resource::pixmap("top_bt_back.png"),
                              QPixmap(),
                              Resource::pixmap("top_bt_back_disabled.png"));

    m_optionsButton = new Button(Resource::pixmap("top_bt_options.png"),
                                 QPixmap(),
                                 Resource::pixmap("top_bt_options_disabled.png"));

    connect(m_backButton, SIGNAL(clicked()), SLOT(backClicked()));
    connect(m_optionsButton, SIGNAL(clicked()), SLOT(optionsClicked()));

    topLayout->addItem(m_optionsButton);
    topLayout->addStretch(1);
    topLayout->addItem(m_menu);
    topLayout->addStretch(1);
    topLayout->addItem(m_backButton);

    m_animationInOut = new QParallelAnimationGroup(this);
    connect(m_animationInOut, SIGNAL(finished()), this, SLOT(transitionFinished()));

    m_optionsButton->setEnabled(false);

    m_oldSlot = new PageSlot(this);
    m_newSlot = new PageSlot(this);
    m_oldSlot->setPos(0, m_topOffset);
    m_newSlot->setPos(0, m_topOffset);
}

bool PageView::add(View *view)
{
    if (!view || isAnimating())
        return false;

    view->setPageView(this);

    if (m_views.isEmpty()) {
        m_views.push(view);
        m_menu->setText(view->title());
        m_oldSlot->setContents(view);
    } else
        animateTransition(m_views.top(), view, false);

    return true;
}

bool PageView::back()
{
    if (m_views.count() < 2 || isAnimating())
        return false;

    View *oldView = m_views.pop();
    View *newView = m_views.top();

    animateTransition(oldView, newView, true);
    return true;
}

bool PageView::isAnimating() const
{
    return (m_animationInOut->state() == QAbstractAnimation::Running);
}

void PageView::backClicked()
{
    if (m_views.count() < 2)
        QApplication::quit();
    else
        back();
}

void PageView::optionsClicked()
{
    qWarning("options clicked");
}

void PageView::transitionFinished()
{
    View *newView = m_newSlot->contents();
    View *oldView = m_oldSlot->contents();

    if (m_isBack) {
        m_oldSlot->setContents(0);
        delete oldView;
    } else {
        oldView->hide();
        m_views.push(newView);
    }

    m_menu->setText(newView->title());
}

void PageView::animateTransition(View *oldView, View *newView, bool isBack)
{
    m_isBack = isBack;
    m_oldSlot->setContents(oldView);
    m_newSlot->setContents(newView);

    m_animationInOut->clear();

    newView->show();

    QAbstractAnimation *inAnim;
    QAbstractAnimation *outAnim;

    if (isBack) {
        inAnim = m_newSlot->createAnimation(PageSlot::MoveInLeft);
        outAnim = m_oldSlot->createAnimation(PageSlot::MoveOutRight);
    } else {
        inAnim = m_newSlot->createAnimation(PageSlot::MoveInRight);
        outAnim = m_oldSlot->createAnimation(PageSlot::MoveOutLeft);
    }

    m_animationInOut->addAnimation(inAnim);
    m_animationInOut->addAnimation(outAnim);
    m_animationInOut->start();
}

void PageView::resizeEvent(QGraphicsSceneResizeEvent *event)
{
    QGraphicsWidget::resizeEvent(event);

    QSizeF newSize = event->newSize();
    newSize.setHeight(newSize.height() - m_topOffset);

    m_oldSlot->resize(newSize);
    m_newSlot->resize(newSize);
}

#include "pageview.moc"