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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

    \o QGraphicsPixelizeEffect - pixelizes the item with any pixel size

    \o QGraphicsGrayscaleEffect - renders the item in shades of gray

    \o QGraphicsBloomEffect - applies a blooming / glowing effect

    \endlist

    \img graphicseffect-effects.png

    \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()

    function accepts two arguments: the painter and a pointer to the source

    (QGraphicsEffectSource). The source provides extra context information,

    such as a pointer to the item that is rendering the effect, any cached

    pixmap data, or the device rectangle bounds. For more information, refer to

    the documenation for draw(). To obtain a pointer to the current source,

    simply call source().

    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

    virtual boundingRectFor() function, and call updateBoundingRect() to notify

    the framework whenever this rectangle changes. The virtual

    sourceBoundingRectChanged() function is called to notify the effects that

    the source's bounding rectangle has changed - e.g., if the source is a

    QGraphicsRectItem and its rectangle parameters have changed.

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

    QGraphicsEffectSource

*/

#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.

    \since 4.6

    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 bounds of the current painter's device.

    This function is useful when you want to draw something in device

    coordinates and ensure the size of the pixmap is not bigger than the size

    of the device.

    Calling QGraphicsEffectSource::pixmap(Qt::DeviceCoordinates) always returns

    a pixmap which is bound to the device's size.

    \sa pixmap()

*/

QRect QGraphicsEffectSource::deviceRect() const

{

    return d_func()->deviceRect();

}

/*!

    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()

*/

void QGraphicsEffectSource::draw(QPainter *painter)

{

    d_func()->draw(painter);

}

/*!

    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.

    \sa QGraphicsEffect::draw(), boundingRect(), deviceRect()

*/

QPixmap QGraphicsEffectSource::pixmap(Qt::CoordinateSystem system, QPoint *offset) const

{

    Q_D(const QGraphicsEffectSource);

    QPixmap pm;

    if (d->m_cachedSystem == system)

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

    if (pm.isNull()) {

        pm = d->pixmap(system, &d->m_cachedOffset);

        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);

}

/*!

    Returns the bounding rectangle for this effect, i.e., the bounding

    rectangle of the source, adjusted by any margins applied by the effect

    itself.

    \sa boundingRectFor(), updateBoundingRect()

*/

QRectF QGraphicsEffect::boundingRect() const

{

    Q_D(const QGraphicsEffect);

    if (d->source)

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

    return QRectF();

}

/*!

    Returns the bounding rectangle for this effect, given the provided source

    \a rect. When writing you own custom effect, you must call

    updateBoundingRect() whenever any parameters are changed that may cause

    this this function to return a different value.

    \sa boundingRect()

*/

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;

    if (d->source)

        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;

}

/*!

    This function notifies the effect framework when the effect's bounding

    rectangle has changed. As a custom effect author, you must call this

    function whenever you change any parameters that will cause the virtual

    boundingRectFor() function to return a different value.

    This function will call update() if this is necessary.

    \sa boundingRectFor(), boundingRect()

*/

void QGraphicsEffect::updateBoundingRect()

{

    Q_D(QGraphicsEffect);

    if (d->source)

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

}

/*!

    \fn virtual void QGraphicsEffect::draw(QPainter *painter,

    QGraphicsEffectSource *source) = 0

    This pure virtual function draws the effect and is called whenever the

    source() needs to be drawn.

    Reimplement this function in a QGraphicsEffect subclass to provide the

    effect's drawing implementation, using \a painter. The \a source parameter

    is provided for convenience; its value is the same as source().

    For example:

    \snippet doc/src/snippets/code/src_gui_effects_qgraphicseffect.cpp 1

    This function should not be called explicitly by the user, since it is

    meant for reimplementation purposes only.

    \sa QGraphicsEffectSource

*/

/*!

    \enum QGraphicsEffect::ChangeFlag

    This enum describes what has changed in QGraphicsEffectSource.

    \value SourceAttached The effect is installed on a source.

    \value SourceDetached The effect is uninstalled on a source.

    \value SourceBoundingRectChanged The bounding rect of the source has

           changed.

    \value SourceInvalidated The visual appearance of the source has changed.

*/

/*!

    This virtual function is called by QGraphicsEffect to notify the effect

    that the source has changed. If the effect applies any cache, then this

    cache must be purged in order to reflect the new appearance of the source.

    The \a flags describes what has changed.

*/

void QGraphicsEffect::sourceChanged(ChangeFlags flags)

{

    Q_UNUSED(flags);

}

/*!

    \class QGraphicsGrayscaleEffect

    \brief The QGraphicsGrayscaleEffect class provides a grayscale effect.

    \since 4.6

    A grayscale effect renders the source in shades of gray.

    \img graphicseffect-grayscale.png

    \sa QGraphicsDropShadowEffect, QGraphicsBlurEffect, QGraphicsPixelizeEffect,

        QGraphicsColorizeEffect, QGraphicsOpacityEffect

*/

/*!

    Constructs a new QGraphicsGrayscale instance.

    The \a parent parameter is passed to QGraphicsEffect's constructor.

*/

QGraphicsGrayscaleEffect::QGraphicsGrayscaleEffect(QObject *parent)

    : QGraphicsEffect(*new QGraphicsGrayscaleEffectPrivate, parent)

{

}

/*!

    Destroys the effect.

*/

QGraphicsGrayscaleEffect::~QGraphicsGrayscaleEffect()

{

}

/*!

    \property QGraphicsGrayscaleEffect::strength

    \brief the strength of the effect.

    By default, the strength is 1.0.

    A strength 0.0 equals to no effect, while 1.0 means full grayscale.

*/

qreal QGraphicsGrayscaleEffect::strength() const

{

    Q_D(const QGraphicsGrayscaleEffect);

    return d->filter->strength();

}

void QGraphicsGrayscaleEffect::setStrength(qreal strength)

{

    Q_D(QGraphicsGrayscaleEffect);

    if (qFuzzyCompare(d->filter->strength(), strength))

        return;

    d->filter->setStrength(strength);

    d->opaque = !qFuzzyIsNull(strength);

    update();

    emit strengthChanged(strength);

}

/*! \fn void QGraphicsGrayscaleEffect::strengthChanged(qreal strength)

  This signal is emitted whenever setStrength() changes the grayscale

  strength property. \a strength contains the new strength value of

  the grayscale effect.

 */

/*!

    \reimp

*/

void QGraphicsGrayscaleEffect::draw(QPainter *painter, QGraphicsEffectSource *source)

{

    Q_D(QGraphicsGrayscaleEffect);

    if (!d->opaque) {