功能:在鼠标移动时,用QToolTip显示鼠标当前位置(y轴值是当前鼠标所在的轴矩形的y值)
//如下代码放置与鼠标移动事件中
int x_pos = event->pos().x();
int y_pos = event->pos().y();
//将鼠标坐标值换成曲线x轴的值
float x_value = xAxis->pixelToCoord(x_pos);
float y_value2 =0;
if(axisRectAt(event->pos())!=nullptr)
y_value2 = this->axisRectAt(event->pos())->axis(QCPAxis::atLeft)->pixelToCoord(y_pos);
//定义标签格式
QString tip;
tip = QString::number(x_value) + "," + QString::number(y_value2);
// 直接用tooltip显示
QToolTip::showText(cursor().pos(),tip,this);
https://blog.youkuaiyun.com/weixin_43637946/article/details/112546572