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** Copyright (C) 2016 The Qt Company Ltd.
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** This file is part of the Qt Quick Templates 2 module of the Qt Toolkit.
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****************************************************************************/

#include "qquickpageindicator_p.h"
#include "qquickcontrol_p_p.h"

#include <QtCore/qmath.h>
#include <QtQuick/private/qquickitem_p.h>
#include <QtQuick/private/qquickitemchangelistener_p.h>

QT_BEGIN_NAMESPACE

/*!
    \qmltype PageIndicator
    \inherits Control
    \instantiates QQuickPageIndicator
    \inqmlmodule QtQuick.Controls
    \since 5.7
    \ingroup qtquickcontrols2-indicators
    \brief Indicates the currently active page.

    PageIndicator is used to indicate the currently active page
    in a container of multiple pages. PageIndicator consists of
    delegate items that present pages.

    \image qtquickcontrols2-pageindicator.png

    \snippet qtquickcontrols2-pageindicator.qml 1

    \sa SwipeView, {Customizing PageIndicator}, {Indicator Controls}
*/

class QQuickPageIndicatorPrivate : public QQuickControlPrivate, public QQuickItemChangeListener
{
    Q_DECLARE_PUBLIC(QQuickPageIndicator)

public:
    QQuickPageIndicatorPrivate() : count(0), currentIndex(0),
        interactive(false), delegate(nullptr), pressedItem(nullptr)
    {
    }

    QQuickItem *itemAt(const QPoint &pos) const;
    void updatePressed(bool pressed, const QPoint &pos = QPoint());
    void setContextProperty(QQuickItem *item, const QString &name, const QVariant &value);

    void itemChildAdded(QQuickItem *, QQuickItem *child);

    int count;
    int currentIndex;
    bool interactive;
    QQmlComponent *delegate;
    QQuickItem *pressedItem;
};

QQuickItem *QQuickPageIndicatorPrivate::itemAt(const QPoint &pos) const
{
    Q_Q(const QQuickPageIndicator);
    if (!contentItem || !q->contains(pos))
        return nullptr;

    QPointF contentPos = q->mapToItem(contentItem, pos);
    QQuickItem *item = contentItem->childAt(contentPos.x(), contentPos.y());
    while (item && item->parentItem() != contentItem)
        item = item->parentItem();
    if (item && !QQuickItemPrivate::get(item)->isTransparentForPositioner())
        return item;

    // find the nearest
    qreal distance = qInf();
    QQuickItem *nearest = nullptr;
    const auto childItems = contentItem->childItems();
    for (QQuickItem *child : childItems) {
        if (QQuickItemPrivate::get(child)->isTransparentForPositioner())
            continue;

        QPointF center = child->boundingRect().center();
        QPointF pt = contentItem->mapToItem(child, contentPos);

        qreal len = QLineF(center, pt).length();
        if (len < distance) {
            distance = len;
            nearest = child;
        }
    }
    return nearest;
}

void QQuickPageIndicatorPrivate::updatePressed(bool pressed, const QPoint &pos)
{
    QQuickItem *prevItem = pressedItem;
    pressedItem = pressed ? itemAt(pos) : nullptr;
    if (prevItem != pressedItem) {
        setContextProperty(prevItem, QStringLiteral("pressed"), false);
        setContextProperty(pressedItem, QStringLiteral("pressed"), pressed);
    }
}

void QQuickPageIndicatorPrivate::setContextProperty(QQuickItem *item, const QString &name, const QVariant &value)
{
    QQmlContext *context = qmlContext(item);
    if (context && context->isValid()) {
        context = context->parentContext();
        if (context && context->isValid())
            context->setContextProperty(name, value);
    }
}

void QQuickPageIndicatorPrivate::itemChildAdded(QQuickItem *, QQuickItem *child)
{
    if (!QQuickItemPrivate::get(child)->isTransparentForPositioner())
        setContextProperty(child, QStringLiteral("pressed"), false);
}

QQuickPageIndicator::QQuickPageIndicator(QQuickItem *parent) :
    QQuickControl(*(new QQuickPageIndicatorPrivate), parent)
{
}

/*!
    \qmlproperty int QtQuick.Controls::PageIndicator::count

    This property holds the number of pages.
*/
int QQuickPageIndicator::count() const
{
    Q_D(const QQuickPageIndicator);
    return d->count;
}

void QQuickPageIndicator::setCount(int count)
{
    Q_D(QQuickPageIndicator);
    if (d->count == count)
        return;

    d->count = count;
    emit countChanged();
}

/*!
    \qmlproperty int QtQuick.Controls::PageIndicator::currentIndex

    This property holds the index of the current page.
*/
int QQuickPageIndicator::currentIndex() const
{
    Q_D(const QQuickPageIndicator);
    return d->currentIndex;
}

void QQuickPageIndicator::setCurrentIndex(int index)
{
    Q_D(QQuickPageIndicator);
    if (d->currentIndex == index)
        return;

    d->currentIndex = index;
    emit currentIndexChanged();
}

/*!
    \qmlproperty bool QtQuick.Controls::PageIndicator::interactive

    This property holds whether the control is interactive. An interactive page indicator
    reacts to presses and automatically changes the \l {currentIndex}{current index}
    appropriately.

    The default value is \c false.
*/
bool QQuickPageIndicator::isInteractive() const
{
    Q_D(const QQuickPageIndicator);
    return d->interactive;
}

void QQuickPageIndicator::setInteractive(bool interactive)
{
    Q_D(QQuickPageIndicator);
    if (d->interactive == interactive)
        return;

    d->interactive = interactive;
    setAcceptedMouseButtons(interactive ? Qt::LeftButton : Qt::NoButton);
    emit interactiveChanged();
}

/*!
    \qmlproperty Component QtQuick.Controls::PageIndicator::delegate

    This property holds a delegate that presents a page.

    The following properties are available in the context of each delegate:
    \table
        \row \li \b index : int \li The index of the item
        \row \li \b pressed : bool \li Whether the item is pressed
    \endtable
*/
QQmlComponent *QQuickPageIndicator::delegate() const
{
    Q_D(const QQuickPageIndicator);
    return d->delegate;
}

void QQuickPageIndicator::setDelegate(QQmlComponent *delegate)
{
    Q_D(QQuickPageIndicator);
    if (d->delegate == delegate)
        return;

    d->delegate = delegate;
    emit delegateChanged();
}

void QQuickPageIndicator::contentItemChange(QQuickItem *newItem, QQuickItem *oldItem)
{
    Q_D(QQuickPageIndicator);
    QQuickControl::contentItemChange(newItem, oldItem);
    if (oldItem)
        QQuickItemPrivate::get(oldItem)->removeItemChangeListener(d, QQuickItemPrivate::Children);
    if (newItem)
        QQuickItemPrivate::get(newItem)->addItemChangeListener(d, QQuickItemPrivate::Children);
}

void QQuickPageIndicator::mousePressEvent(QMouseEvent *event)
{
    Q_D(QQuickPageIndicator);
    if (d->interactive) {
        d->updatePressed(true, event->pos());
        event->accept();
    }
}

void QQuickPageIndicator::mouseMoveEvent(QMouseEvent *event)
{
    Q_D(QQuickPageIndicator);
    if (d->interactive) {
        d->updatePressed(true, event->pos());
        event->accept();
    }
}

void QQuickPageIndicator::mouseReleaseEvent(QMouseEvent *event)
{
    Q_D(QQuickPageIndicator);
    if (d->interactive) {
        if (d->pressedItem)
            setCurrentIndex(d->contentItem->childItems().indexOf(d->pressedItem));
        d->updatePressed(false);
        event->accept();
    }
}

void QQuickPageIndicator::mouseUngrabEvent()
{
    Q_D(QQuickPageIndicator);
    if (d->interactive)
        d->updatePressed(false);
}

#ifndef QT_NO_ACCESSIBILITY
QAccessible::Role QQuickPageIndicator::accessibleRole() const
{
    return QAccessible::Indicator;
}
#endif

QT_END_NAMESPACE