Creating games with QCanvas

Author: Gunnstein Lye

Publishing date: 27.10.2000 14:00

void BounceCanvasView::contentsMouseReleaseEvent( QMouseEvent* )
{
    if ( Moving )    // if we are holding the ball
    {
        Timer->stop();    // stop the timer

        if ( MousePosQueue.count() )  // if we have recorded mouse positions...
        {
            // ...then calculate average velocity
            int count = MousePosQueue.count();
            QPoint velocity( 0, 0 );
            QPoint pos;
            QPoint prevPos = *MousePosQueue.head();

            while ( MousePosQueue.count() )
            {
                pos = *MousePosQueue.dequeue();
                velocity += pos - prevPos;
                prevPos = pos;
            }

            // set the balls new velocity
            Moving->setXVelocity( velocity.x() / count );
            Moving->setYVelocity( velocity.y() / count );
        }
        else  // if we haven't recorded anything (fast click)
        {
            // set zero velocity (we drop the ball)
            Moving->setXVelocity( 0 );
            Moving->setYVelocity( 0 );
        }

        Moving->setZ( 1 );
        canvas()->setAdvancePeriod( 10 );  // restart the animation
        Moving = 0;     // clear the pointer, we are no longer holding the ball
    }
}