QGraphicsScene绘制网格背景

博客转载自：https://blog.csdn.net/u010177010/article/details/51496038

//两条轴线QPolygonF myPolygon1;
myPolygon1 << QPointF(0,10) << QPointF(20,10);
QPolygonF myPolygon2;
myPolygon2 << QPointF(10,0) << QPointF(10,20);  //图像大小
QPixmap pixmap(20, 20);
pixmap.fill(Qt::transparent);
QPainter painter(&pixmap);
//虚线格式 　 QVector<qreal> dashes;
qreal space = 2;
dashes << 2 << space << 2 <<space;
QPen pen(Qt::lightGray,1);
pen.setDashPattern(dashes);
pen.setWidth(1);
  painter.setPen(pen);
painter.translate(0, 0);
painter.drawPolyline(myPolygon1);
painter.drawPolyline(myPolygon2);
m_scene->setBackgroundBrush(pixmap);