QGraphicsScene繪制網格背景

 給QGraphicsScene繪制網格背景

    QPolygonF mypolygon1,mypolygon2;
    mypolygon1<<QPointF(0,5)<<QPointF(10,5);
    mypolygon2<<QPointF(5,0)<<QPointF(5,10);
    QPixmap pix(10,10);
    pix.fill(Qt::transparent);
    QPainter painter(&pix);
    QVector <qreal> dashes;
    dashes<<2<<2<<2<<2;    
    QPen pen(Qt::darkCyan,0.2);
    pen.setDashPattern(dashes);
    painter.setPen(pen);
    painter.translate(0,0);
    painter.drawPolyline(mypolygon1);
    painter.drawPolyline(mypolygon2);
    scene->setBackgroundBrush(pix);