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#include "shadoweffect.h"

#include <math.h>

ShadowEffect::ShadowEffect(QGraphicsItem *item, QGraphicsItem *source)
    : QGraphicsShadowEffect()
    , item(item), m_lightSource(source)
{
    setBlurRadius(8);
}

void ShadowEffect::adjustForItem()
{
    QPointF delta = item->pos() - m_lightSource->pos();
    setShadowOffset(delta.toPoint() / 30);

    qreal dx = delta.x();
    qreal dy = delta.y();
    qreal dd = sqrt(dx * dx + dy * dy);
    setOpacity(qBound(0.4, 1 - dd / 200.0, 0.7));
}

QRectF ShadowEffect::boundingRectFor(const QRectF &rect) const
{
    const_cast<ShadowEffect *>(this)->adjustForItem();
    return QGraphicsShadowEffect::boundingRectFor(rect);
}

void ShadowEffect::draw(QPainter *painter, QGraphicsEffectSource *source)
{
    adjustForItem();
    QGraphicsShadowEffect::draw(painter, source);
}