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/*!

    \class QGraphicsEffect

    \brief The QGraphicsEffect class is the base class for all graphics

           effects.

    \since 4.6

    \ingroup multimedia

    \ingroup graphicsview-api

    Effects alter the appearance of elements by hooking into the rendering

    pipeline and operating between the source (e.g., a QGraphicsPixmapItem)

    and the destination device (e.g., QGraphicsView's viewport). Effects can be

    disabled by calling setEnabled(false). If effects are disabled, the source

    is rendered directly.

    To add a visual effect to a QGraphicsItem, for example, you can use one of

    the standard effects, or alternately, create your own effect by creating a

    subclass of QGraphicsEffect. The effect can then be installed on the item

    using QGraphicsItem::setGraphicsEffect().

    Qt provides the following standard effects:

    \list

    \o QGraphicsBlurEffect - blurs the item by a given radius

    \o QGraphicsDropShadowEffect - renders a dropshadow behind the item

    \o QGraphicsColorizeEffect - renders the item in shades of any given color

    \o QGraphicsOpacityEffect - renders the item with an opacity

    \endlist

    \img graphicseffect-widget.png

    For more information on how to use each effect, refer to the specific

    effect's documentation.

    To create your own custom effect, create a subclass of QGraphicsEffect (or

    any other existing effects) and reimplement the virtual function draw().

    This function is called whenever the effect needs to redraw. The draw()

    If your effect changes, use update() to request for a redraw. If your

    custom effect changes the bounding rectangle of the source, e.g., a radial

    glow effect may need to apply an extra margin, you can reimplement the

    QGraphicsRectItem and its rectangle parameters have changed.

*/

#include "qgraphicseffect_p.h"

#include <QtGui/qimage.h>

#include <QtGui/qpainter.h>

#include <QtCore/qrect.h>

#include <QtCore/qdebug.h>

#include <private/qdrawhelper_p.h>

QT_BEGIN_NAMESPACE

/*!

    \class QGraphicsEffectSource

    \brief The QGraphicsEffectSource class represents the source on which a

           QGraphicsEffect is installed on.

    When a QGraphicsEffect is installed on a QGraphicsItem, for example, this

    class will act as a wrapper around QGraphicsItem. Then, calling update() is

    effectively the same as calling QGraphicsItem::update().

    QGraphicsEffectSource also provides a pixmap() function which creates a

    pixmap with the source painted into it.

    \sa QGraphicsItem::setGraphicsEffect(), QWidget::setGraphicsEffect().

*/

/*!

    \internal

*/

QGraphicsEffectSource::QGraphicsEffectSource(QGraphicsEffectSourcePrivate &dd, QObject *parent)

    : QObject(dd, parent)

{}

/*!

    Destroys the effect source.

*/

QGraphicsEffectSource::~QGraphicsEffectSource()

{}

/*!

    Returns the bounding rectangle of the source mapped to the given \a system.

    \sa draw()

*/

QRectF QGraphicsEffectSource::boundingRect(Qt::CoordinateSystem system) const

{

    return d_func()->boundingRect(system);

}

/*!

    Returns a pointer to the item if this source is a QGraphicsItem; otherwise

    returns 0.

    \sa widget()

*/

const QGraphicsItem *QGraphicsEffectSource::graphicsItem() const

{

    return d_func()->graphicsItem();

}

/*!

    Returns a pointer to the widget if this source is a QWidget; otherwise

    returns 0.

    \sa graphicsItem()

*/

const QWidget *QGraphicsEffectSource::widget() const

{

    return d_func()->widget();

}

/*!

    Returns a pointer to the style options (used when drawing the source) if

    available; otherwise returns 0.

    \sa graphicsItem(), widget()

*/

const QStyleOption *QGraphicsEffectSource::styleOption() const

{

    return d_func()->styleOption();

}

/*!

    Draws the source using the given \a painter.

    This function should only be called from QGraphicsEffect::draw().

    For example:

    \snippet doc/src/snippets/code/src_gui_effects_qgraphicseffect.cpp 0

    \sa QGraphicsEffect::draw()

*/

{

}

/*!

    Schedules a redraw of the source. Call this function whenever the source

    needs to be redrawn.

    \sa QGraphicsEffect::updateBoundingRect(), QWidget::update(),

        QGraphicsItem::update(),

*/

void QGraphicsEffectSource::update()

{

    d_func()->update();

}

/*!

    Returns true if the source effectively is a pixmap, e.g., a

    QGraphicsPixmapItem.

    This function is useful for optimization purposes. For instance, there's no

    point in drawing the source in device coordinates to avoid pixmap scaling

    if this function returns true - the source pixmap will be scaled anyways.

*/

bool QGraphicsEffectSource::isPixmap() const

{

    return d_func()->isPixmap();

}

/*!

    Returns a pixmap with the source painted into it.

    The \a system specifies which coordinate system to be used for the source.

    The optional \a offset parameter returns the offset where the pixmap should

    be painted at using the current painter.

    The returned pixmap is bound to the current painter's device rectangle when

    \a system is Qt::DeviceCoordinates.

*/

{

    Q_D(const QGraphicsEffectSource);

    QPixmap pm;

        QPixmapCache::find(d->m_cacheKey, &pm);

    if (pm.isNull()) {

        d->m_cachedSystem = system;

        d->invalidateCache();

        d->m_cacheKey = QPixmapCache::insert(pm);

    }

    if (offset)

        *offset = d->m_cachedOffset;

    return pm;

}

/*!

    Constructs a new QGraphicsEffect instance having the

    specified \a parent.

*/

QGraphicsEffect::QGraphicsEffect(QObject *parent)

    : QObject(*new QGraphicsEffectPrivate, parent)

{

}

/*!

    \internal

*/

QGraphicsEffect::QGraphicsEffect(QGraphicsEffectPrivate &dd, QObject *parent)

    : QObject(dd, parent)

{

}

/*!

    Removes the effect from the source, and destroys the graphics effect.

*/

QGraphicsEffect::~QGraphicsEffect()

{

    Q_D(QGraphicsEffect);

    d->setGraphicsEffectSource(0);

}

/*!

    \sa boundingRectFor(), updateBoundingRect()

*/

QRectF QGraphicsEffect::boundingRect() const

{

    Q_D(const QGraphicsEffect);

    if (d->source)

        return boundingRectFor(d->source->boundingRect());

    return QRectF();

}

/*!

*/

QRectF QGraphicsEffect::boundingRectFor(const QRectF &rect) const

{

    return rect;

}

/*!

    \property QGraphicsEffect::enabled

    \brief whether the effect is enabled or not.

    If an effect is disabled, the source will be rendered with as normal, with

    no interference from the effect. If the effect is enabled, the source will

    be rendered with the effect applied.

    This property is enabled by default.

    Using this property, you can disable certain effects on slow platforms, in

    order to ensure that the user interface is responsive.

*/

bool QGraphicsEffect::isEnabled() const

{

    Q_D(const QGraphicsEffect);

    return d->isEnabled;

}

void QGraphicsEffect::setEnabled(bool enable)

{

    Q_D(QGraphicsEffect);

    if (d->isEnabled == enable)

        return;

    d->isEnabled = enable;

        d->source->d_func()->effectBoundingRectChanged();

    emit enabledChanged(enable);

}

/*!

    \fn void QGraphicsEffect::enabledChanged(bool enabled)

    This signal is emitted whenever the effect is enabled or disabled.

    The \a enabled parameter holds the effects's new enabled state.

    \sa isEnabled()

*/

/*!

    Schedules a redraw of the source. Call this function whenever the source

    needs to be redrawn.

    This convenience function is equivalent to calling

    QGraphicsEffectSource::update().

    \sa updateBoundingRect(), QGraphicsEffectSource::update()

*/

void QGraphicsEffect::update()

{

    Q_D(QGraphicsEffect);

    if (d->source)

        d->source->update();

}

/*!

    Returns a pointer to the source, which provides extra context information

    that can be useful for the effect.

    \sa draw()

*/

QGraphicsEffectSource *QGraphicsEffect::source() const

{

    Q_D(const QGraphicsEffect);

    return d->source;

}