C++ (Qt)
Q_GUI_EXPORT void qt_blurImage( QPainter* p, QImage& blurImage, qreal radius, bool quality, bool alphaOnly, int transposed = 0 );
 
class BlurRectItem : public QGraphicsRectItem
{
public:
	BlurRectItem( const QRectF& rect )
	: QGraphicsRectItem( rect )
	, radius_( 5 )
	, in_grab_( false )
	{
		setZValue( 10000 );
		setFlag( ItemIsMovable );
		setCursor( Qt::OpenHandCursor );
	}
	void paint( QPainter* painter, const QStyleOptionGraphicsItem* option, QWidget* widget = 0 )
	{
		if( in_grab_ )
			return;
		in_grab_ = true;
		QImage img( rect().size().toSize(), QImage::Format_RGB32 );
		QPainter p( &img );
		p.eraseRect( rect() );
		p.setRenderHint( QPainter::Antialiasing );
		scene()->render( &p, QRectF(), sceneBoundingRect() );
		p.end();
		in_grab_ = false;
		painter->save();
		qt_blurImage( painter, img, radius_, true, false );
		painter->restore();
		painter->drawRect( rect() );
	}
	qreal blurRadius() const { return radius_; }
	void setBlurRadius( qreal r ) { radius_ = r; }
 
private:
	bool in_grab_;
	qreal radius_;
};