What is the fastest way to draw a circle ?

[Vladimir]

Hello All !

I'm using QGraphicsView to visualize a huge amount of particles which are basically circles with fixed size (about 14x14px). The particles can have non-integer coordinates so I'm using antialiasing (without it the scene looks just horrible). When the number of particles is around 200 performance becomes very poor. I've tried drawing using two different methods:

painter->setPen(Qt::NoPen);
    painter->setBrush(Qt::black);
    painter->drawEllipse(QRectF(-radius,-radius,radius*2,radius*2));

painter->setPen(Qt::NoPen);
    painter->setBrush(Qt::black);
    painter->drawEllipse(QRectF(-radius,-radius,radius*2,radius*2));

To copy to clipboard, switch view to plain text mode 

and

painter->setPen(QPen(Qt::black, radius));
    painter->drawPoint(0,0);

painter->setPen(QPen(Qt::black, radius));
    painter->drawPoint(0,0);

To copy to clipboard, switch view to plain text mode 

Both gives approx. the same performance. I've also tried drawing in-advance into QPixmap, but then I can't place that pixmap at non-integer position and there is very noticeable jitter when particle moves.

Are there any suggestions on how to improve drawing performance ? Thanks in advance !