/****************************************************************************
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** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
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** Contact: Nokia Corporation (qt-info@nokia.com)
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** This file is part of the QtDeclarative module of the Qt Toolkit.
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** contained in the Technology Preview License Agreement accompanying
** this package.
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** 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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**
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** rights.  These rights are described in the Nokia Qt LGPL Exception
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** If you have questions regarding the use of this file, please contact
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****************************************************************************/

#include "private/qdeclarativeloader_p_p.h"

#include <qdeclarativeinfo.h>
#include <qdeclarativeengine_p.h>
#include <qdeclarativeglobal_p.h>

QT_BEGIN_NAMESPACE

QDeclarativeLoaderPrivate::QDeclarativeLoaderPrivate()
    : item(0), component(0), ownComponent(false)
{
}

QDeclarativeLoaderPrivate::~QDeclarativeLoaderPrivate()
{
}

void QDeclarativeLoaderPrivate::itemGeometryChanged(QDeclarativeItem *resizeItem, const QRectF &newGeometry, const QRectF &oldGeometry)
{
    if (resizeItem == item)
        _q_updateSize(false);
    QDeclarativeItemChangeListener::itemGeometryChanged(resizeItem, newGeometry, oldGeometry);
}

void QDeclarativeLoaderPrivate::clear()
{
    if (ownComponent) {
        component->deleteLater();
        component = 0;
        ownComponent = false;
    }
    source = QUrl();

    if (item) {
        if (QDeclarativeItem *qmlItem = qobject_cast<QDeclarativeItem*>(item)) {
            QDeclarativeItemPrivate *p =
                    static_cast<QDeclarativeItemPrivate *>(QGraphicsItemPrivate::get(qmlItem));
            p->removeItemChangeListener(this, QDeclarativeItemPrivate::Geometry);
        }

        // We can't delete immediately because our item may have triggered
        // the Loader to load a different item.
        item->setVisible(false);
        item->setParentItem(0);
        item->deleteLater();
        item = 0;
    }
}

void QDeclarativeLoaderPrivate::initResize()
{
    Q_Q(QDeclarativeLoader);
    if (QDeclarativeItem *qmlItem = qobject_cast<QDeclarativeItem*>(item)) {
        QDeclarativeItemPrivate *p =
                static_cast<QDeclarativeItemPrivate *>(QGraphicsItemPrivate::get(qmlItem));
        p->addItemChangeListener(this, QDeclarativeItemPrivate::Geometry);
    } else if (item && item->isWidget()) {
        QGraphicsWidget *widget = static_cast<QGraphicsWidget*>(item);
        widget->installEventFilter(q);
    }
    _q_updateSize();
}

/*!
    \qmlclass Loader QDeclarativeLoader
    \since 4.7
    \inherits Item

    \brief The Loader item allows dynamically loading an Item-based
    subtree from a QML URL or Component.

    Loader instantiates an item from a component. The component to
    instantiate may be specified directly by the \c sourceComponent
    property, or loaded from a URL via the \c source property.

    It is also an effective means of delaying the creation of a component
    until it is required:
    \code
    Loader { id: pageLoader }
    Rectangle {
        MouseArea { anchors.fill: parent; onClicked: pageLoader.source = "Page1.qml" }
    }
    \endcode

    If the Loader source is changed, any previous items instantiated
    will be destroyed.  Setting \c source to an empty string, or setting
    sourceComponent to \e undefined
    will destroy the currently instantiated items, freeing resources
    and leaving the Loader empty.  For example:

    \code
    pageLoader.source = ""
      or
    pageLoader.sourceComponent = undefined
    \endcode

    unloads "Page1.qml" and frees resources consumed by it.

    \sa {dynamic-object-creation}{Dynamic Object Creation}
*/

/*!
    \internal
    \class QDeclarativeLoader
    \qmlclass Loader
 */

/*!
    Create a new QDeclarativeLoader instance.
 */
QDeclarativeLoader::QDeclarativeLoader(QDeclarativeItem *parent)
  : QDeclarativeItem(*(new QDeclarativeLoaderPrivate), parent)
{
    Q_D(QDeclarativeItem);
    d->flags |= QGraphicsItem::ItemIsFocusScope;
}

/*!
    Destroy the loader instance.
 */
QDeclarativeLoader::~QDeclarativeLoader()
{
}

/*!
    \qmlproperty url Loader::source
    This property holds the URL of the QML component to
    instantiate.

    \sa sourceComponent, status, progress
*/
QUrl QDeclarativeLoader::source() const
{
    Q_D(const QDeclarativeLoader);
    return d->source;
}

void QDeclarativeLoader::setSource(const QUrl &url)
{
    Q_D(QDeclarativeLoader);
    if (d->source == url)
        return;

    d->clear();

    d->source = url;
    if (d->source.isEmpty()) {
        emit sourceChanged();
        emit statusChanged();
        emit progressChanged();
        emit itemChanged();
        return;
    }

    d->component = new QDeclarativeComponent(qmlEngine(this), d->source, this);
    d->ownComponent = true;
    if (!d->component->isLoading()) {
        d->_q_sourceLoaded();
    } else {
        connect(d->component, SIGNAL(statusChanged(QDeclarativeComponent::Status)),
                this, SLOT(_q_sourceLoaded()));
        connect(d->component, SIGNAL(progressChanged(qreal)),
                this, SIGNAL(progressChanged()));
        emit statusChanged();
        emit progressChanged();
        emit sourceChanged();
        emit itemChanged();
    }
}

/*!
    \qmlproperty Component Loader::sourceComponent
    The sourceComponent property holds the \l{Component} to instantiate.

    \qml
    Item {
        Component {
            id: redSquare
            Rectangle { color: "red"; width: 10; height: 10 }
        }

        Loader { sourceComponent: redSquare }
        Loader { sourceComponent: redSquare; x: 10 }
    }
    \endqml

    \sa source, progress
*/

QDeclarativeComponent *QDeclarativeLoader::sourceComponent() const
{
    Q_D(const QDeclarativeLoader);
    return d->component;
}

void QDeclarativeLoader::setSourceComponent(QDeclarativeComponent *comp)
{
    Q_D(QDeclarativeLoader);
    if (comp == d->component)
        return;

    d->clear();

    d->component = comp;
    d->ownComponent = false;
    if (!d->component) {
        emit sourceChanged();
        emit statusChanged();
        emit progressChanged();
        emit itemChanged();
        return;
    }

    if (!d->component->isLoading()) {
        d->_q_sourceLoaded();
    } else {
        connect(d->component, SIGNAL(statusChanged(QDeclarativeComponent::Status)),
                this, SLOT(_q_sourceLoaded()));
        connect(d->component, SIGNAL(progressChanged(qreal)),
                this, SIGNAL(progressChanged()));
        emit progressChanged();
        emit sourceChanged();
        emit statusChanged();
        emit itemChanged();
    }
}

void QDeclarativeLoader::resetSourceComponent()
{
    setSourceComponent(0);
}

void QDeclarativeLoaderPrivate::_q_sourceLoaded()
{
    Q_Q(QDeclarativeLoader);

    if (component) {
        if (!component->errors().isEmpty()) {
            QDeclarativeEnginePrivate::warning(qmlEngine(q), component->errors());
            emit q->sourceChanged();
            emit q->statusChanged();
            emit q->progressChanged();
            return;
        }

        QDeclarativeContext *ctxt = new QDeclarativeContext(qmlContext(q));
        ctxt->setContextObject(q);

        QDeclarativeComponent *c = component;
        QObject *obj = component->create(ctxt);
        if (component != c) {
            // component->create could trigger a change in source that causes
            // component to be set to something else. In that case we just
            // need to cleanup.
            delete obj;
            delete ctxt;
            return;
        }
        if (obj) {
            item = qobject_cast<QGraphicsObject *>(obj);
            if (item) {
                QDeclarative_setParent_noEvent(ctxt, obj);
                QDeclarative_setParent_noEvent(item, q);
                item->setParentItem(q);
//                item->setFocus(true);
                initResize();
            } else {
                qmlInfo(q) << QDeclarativeLoader::tr("Loader does not support loading non-visual elements.");
                delete obj;
                delete ctxt;
            }
        } else {
            if (!component->errors().isEmpty())
                QDeclarativeEnginePrivate::warning(qmlEngine(q), component->errors());
            delete obj;
            delete ctxt;
            source = QUrl();
        }
        emit q->sourceChanged();
        emit q->statusChanged();
        emit q->progressChanged();
        emit q->itemChanged();
    }
}

/*!
    \qmlproperty enumeration Loader::status

    This property holds the status of QML loading.  It can be one of:
    \list
    \o Loader.Null - no QML source has been set
    \o Loader.Ready - the QML source has been loaded
    \o Loader.Loading - the QML source is currently being loaded
    \o Loader.Error - an error occurred while loading the QML source
    \endlist

    Note that a change in the status property does not cause anything to happen
    (although it reflects what has happened to the loader internally). If you wish
    to react to the change in status you need to do it yourself, for example in one
    of the following ways:
    \list
    \o Create a state, so that a state change occurs, e.g. State{name: 'loaded'; when: loader.status = Loader.Ready;}
    \o Do something inside the onStatusChanged signal handler, e.g. Loader{id: loader; onStatusChanged: if(loader.status == Loader.Ready) console.log('Loaded');}
    \o Bind to the status variable somewhere, e.g. Text{text: if(loader.status!=Loader.Ready){'Not Loaded';}else{'Loaded';}}
    \endlist
    \sa progress
*/

QDeclarativeLoader::Status QDeclarativeLoader::status() const
{
    Q_D(const QDeclarativeLoader);

    if (d->component)
        return static_cast<QDeclarativeLoader::Status>(d->component->status());

    if (d->item)
        return Ready;

    return d->source.isEmpty() ? Null : Error;
}

/*!
\qmlproperty real Loader::progress

This property holds the progress of loading QML data from the network, from
0.0 (nothing loaded) to 1.0 (finished).  Most QML files are quite small, so
this value will rapidly change from 0 to 1.

\sa status
*/
qreal QDeclarativeLoader::progress() const
{
    Q_D(const QDeclarativeLoader);

    if (d->item)
        return 1.0;

    if (d->component)
        return d->component->progress();

    return 0.0;
}


void QDeclarativeLoaderPrivate::_q_updateSize(bool loaderGeometryChanged)
{
    Q_Q(QDeclarativeLoader);
    if (!item)
        return;
    if (QDeclarativeItem *qmlItem = qobject_cast<QDeclarativeItem*>(item)) {
        q->setImplicitWidth(qmlItem->width());
        if (loaderGeometryChanged && q->widthValid())
            qmlItem->setWidth(q->width());
        q->setImplicitHeight(qmlItem->height());
        if (loaderGeometryChanged && q->heightValid())
            qmlItem->setHeight(q->height());
    } else if (item && item->isWidget()) {
        QGraphicsWidget *widget = static_cast<QGraphicsWidget*>(item);
        QSizeF widgetSize = widget->size();
        q->setImplicitWidth(widgetSize.width());
        if (loaderGeometryChanged && q->widthValid())
            widgetSize.setWidth(q->width());
        q->setImplicitHeight(widgetSize.height());
        if (loaderGeometryChanged && q->heightValid())
            widgetSize.setHeight(q->height());
        if (widget->size() != widgetSize)
            widget->resize(widgetSize);
    }
}

/*!
    \qmlproperty Item Loader::item
    This property holds the top-level item created from source.
*/
QGraphicsObject *QDeclarativeLoader::item() const
{
    Q_D(const QDeclarativeLoader);
    return d->item;
}

void QDeclarativeLoader::geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry)
{
    Q_D(QDeclarativeLoader);
    if (newGeometry != oldGeometry) {
        d->_q_updateSize();
    }
    QDeclarativeItem::geometryChanged(newGeometry, oldGeometry);
}

QVariant QDeclarativeLoader::itemChange(GraphicsItemChange change, const QVariant &value)
{
    Q_D(QDeclarativeLoader);
    if (change == ItemSceneHasChanged) {
        if (d->item && d->item->isWidget()) {
            d->item->removeEventFilter(this);
            d->item->installEventFilter(this);
        }
    }
    return QDeclarativeItem::itemChange(change, value);
}

bool QDeclarativeLoader::eventFilter(QObject *watched, QEvent *e)
{
    Q_D(QDeclarativeLoader);
    if (watched == d->item && e->type() == QEvent::GraphicsSceneResize) {
        if (d->item && d->item->isWidget())
            d->_q_updateSize(false);
    }
    return QDeclarativeItem::eventFilter(watched, e);
}

#include <moc_qdeclarativeloader_p.cpp>

QT_END_NAMESPACE