QGraphicsVIew绘制表格背景

项目场景：

在QGrapicsView中绘制表格状背景

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实现

重写drawBackground方法，内容如下：

	//每50距离绘制一段直线
    QRect r = this->rect();

    QPointF tl = mapToScene(r.topLeft());
    QPointF br = mapToScene(r.bottomRight());

    double left = std::floor(tl.x() / 50);
    double top = std::floor(tl.y() / 50);

    double right = std::ceil(br.x() / 50);
    double bottom = std::ceil(br.y() / 50);

    //vertical lines from left to right
    for (int vi = (int)left; vi <= (int)right; vi++)
    {
        QLineF line(vi * 50, top * 50, vi * 50, bottom * 50);
        painter->drawLine(line);
    }

    //horizontal lines from top to bottom
    for (int hi = (int)top; hi <= (int)bottom; hi++)
    {
        QLineF line(left * 50, hi * 50, right * 50, hi * 50);
        painter->drawLine(line);
    }

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错误提示：

如下代码打印方法参数

void GraphicsView::drawBackground(QPainter* painter, const QRectF& rect)
{
	 qDebug() << rect << this->rect();
}

drawBackground提供的rect长宽不正确，绘制的时候会发现不正常，使用this->rect()即可

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