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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

    \table

    \row

    \o{2,1} \img graphicseffect-plain.png

    \row

    \o \img graphicseffect-blur.png

    \o \img graphicseffect-colorize.png

    \row

    \o \img graphicseffect-opacity.png

    \o \img graphicseffect-drop-shadow.png

    \endtable

    \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 takes the painter with which to draw as an argument. For more

    information, refer to the documenation for draw(). In the draw() function

    you can call sourcePixmap() to get a pixmap of the graphics effect source

    which you can then process.

    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

    sourceChanged() function is called to notify the effects that

    the source has changed in some way - e.g., if the source is a

    QGraphicsRectItem and its rectangle parameters have changed.

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

*/

#include "qgraphicseffect_p.h"

#include "private/qgraphicsitem_p.h"

#include <QtGui/qgraphicsitem.h>

#include <QtGui/qimage.h>

#include <QtGui/qpainter.h>

#include <QtGui/qpaintengine.h>

#include <QtCore/qrect.h>

#include <QtCore/qdebug.h>

#include <private/qdrawhelper_p.h>

#ifndef QT_NO_GRAPHICSEFFECT

QT_BEGIN_NAMESPACE

/*!

    \internal

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

    Calling this function with Qt::DeviceCoordinates outside of

    QGraphicsEffect::draw() will give undefined results, as there is no device

    context available.

    \sa draw()

*/

QRectF QGraphicsEffect::sourceBoundingRect(Qt::CoordinateSystem system) const

{

    Q_D(const QGraphicsEffect);

    if (d->source)

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

    return QRectF();

}

/*!

    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().

    \sa QGraphicsEffect::draw()

*/

void QGraphicsEffectSource::draw(QPainter *painter)

{

    Q_D(const QGraphicsEffectSource);

    QPixmap pm;

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

        QTransform restoreTransform;

        if (d->m_cachedSystem == Qt::DeviceCoordinates) {

            restoreTransform = painter->worldTransform();

            painter->setWorldTransform(QTransform());

        }

        painter->drawPixmap(d->m_cachedOffset, pm);

        if (d->m_cachedSystem == Qt::DeviceCoordinates)

            painter->setWorldTransform(restoreTransform);

    } else {

        d_func()->draw(painter);

    }

}

/*!

    Draws the source directly 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 QGraphicsEffect::drawSource(QPainter *painter)

{

    Q_D(const QGraphicsEffect);

    if (d->source)

        d->source->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 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 QGraphicsEffect::sourceIsPixmap() const

{

    return source() ? source()->isPixmap() : false;

}

/*!

    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 \a mode determines how much of the effect the pixmap will contain.

    By default, the pixmap will contain the whole effect.

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

    \a system is Qt::DeviceCoordinates.

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

*/

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

{

    Q_D(const QGraphicsEffectSource);

    // Shortcut, no cache for childless pixmap items...

    const QGraphicsItem *item = graphicsItem();

    if (system == Qt::LogicalCoordinates && mode == QGraphicsEffect::NoPad && item && isPixmap()) {

        const QGraphicsPixmapItem *pixmapItem = static_cast<const QGraphicsPixmapItem *>(item);

        if (offset)

            *offset = pixmapItem->offset().toPoint();

        return pixmapItem->pixmap();

    }

    if (system == Qt::DeviceCoordinates && item

        && !static_cast<const QGraphicsItemEffectSourcePrivate *>(d_func())->info) {

        qWarning("QGraphicsEffectSource::pixmap: Not yet implemented, lacking device context");

        return QPixmap();

    }

    QPixmap pm;

    if (d->m_cachedSystem == system && d->m_cachedMode == mode)

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

    if (pm.isNull()) {

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

        d->m_cachedSystem = system;

        d->m_cachedMode = mode;

        d->invalidateCache();

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

    }

    if (offset)

        *offset = d->m_cachedOffset;

    return pm;

}

/*!

    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. For control on how the pixmap is

    padded use the \a mode parameter.

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

    \a system is Qt::DeviceCoordinates.

    Calling this function with Qt::DeviceCoordinates outside of

    QGraphicsEffect::draw() will give undefined results, as there is no device

    context available.

    \sa draw(), boundingRect()

*/

QPixmap QGraphicsEffect::sourcePixmap(Qt::CoordinateSystem system, QPoint *offset, QGraphicsEffect::PixmapPadMode mode) const

{

    Q_D(const QGraphicsEffect);

    if (d->source)

        return d->source->pixmap(system, offset, mode);

    return QPixmap();

}

QGraphicsEffectSourcePrivate::~QGraphicsEffectSourcePrivate()

{

    invalidateCache();

}

void QGraphicsEffectSourcePrivate::setCachedOffset(const QPoint &offset)

{

    m_cachedOffset = offset;

}

void QGraphicsEffectSourcePrivate::invalidateCache(InvalidateReason reason) const

{

    if (m_cachedMode != QGraphicsEffect::PadToEffectiveBoundingRect

        && (reason == EffectRectChanged

        return;

    QPixmapCache::remove(m_cacheKey);

}

/*!

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

    bounding rectangle of the source in device coordinates, 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 effective bounding rectangle for this effect, given the

    provided \a rect in the device coordinates. 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 sourceBoundingRect()

*/

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();

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

    }

    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();

}

/*!

    \internal

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

    that can be useful for the effect.

    \sa draw()