在鼠标悬停时显示绘图值 . - 检测散点

3 回答

• 7

  重新实现 QCustomPlot::mouseMoveEvent 或连接到 QCustomPlot::mouseMove .

  然后使用轴' coordToPixel 转换（光标）像素坐标以绘制坐标并使用 QMap::lowerBound(cursorX) 搜索 QCPDataMap 中的最近点 .

  回复于 2024-05-07T02:55:16+08:00
• 2

  您可以轻松地将插槽连接到 QCustomPlot 发出的 mouseMove 信号 . 然后，您可以使用 QCPAxis::pixelToCoord 查找坐标：

  connect(this, SIGNAL(mouseMove(QMouseEvent*)), this,SLOT(showPointToolTip(QMouseEvent*)));
  
  void QCustomPlot::showPointToolTip(QMouseEvent *event)
  {
  
      int x = this->xAxis->pixelToCoord(event->pos().x());
      int y = this->yAxis->pixelToCoord(event->pos().y());
  
      setToolTip(QString("%1 , %2").arg(x).arg(y));
  
  }
  

  回复于 2024-05-07T02:55:16+08:00
• 9

  当您使用X轴的日期时间格式（包括每秒更多点数）时，像素到坐标将失败 . 如果要显示点之间的坐标，那么这是最快的方法

  也许有用（连接信号 QCustomplot::MouseMove ）

  void MainWindow::onMouseMoveGraph(QMouseEvent* evt)
      {
      int x = this->ui->customPlot->xAxis->pixelToCoord(evt->pos().x());
      int y = this->ui->customPlot->yAxis->pixelToCoord(evt->pos().y());
      qDebug()<<"pixelToCoord: "<<data.key<<data.value; //this is correct when step is greater 1 second
  
  if (this->ui->customPlot->selectedGraphs().count()>0)
          {
          QCPGraph* graph = this->ui->customPlot->selectedGraphs().first();
          QCPData data = graph->data()->lowerBound(x).value();
  
          double dbottom = graph->valueAxis()->range().lower;        //Yaxis bottom value
          double dtop = graph->valueAxis()->range().upper;           //Yaxis top value
          long ptop = graph->valueAxis()->axisRect()->top();         //graph top margin
          long pbottom = graph->valueAxis()->axisRect()->bottom();   //graph bottom position
  // result for Y axis
          double valueY = (evt->pos().y() - ptop) / (double)(pbottom - ptop)*(double)(dbottom - dtop) + dtop;
  
  //or shortly for X-axis
          double valueX = (evt->pos().x() - graph->keyAxis()->axisRect()->left());  //graph width in pixels
          double ratio = (double)(graph->keyAxis()->axisRect()->right() - graph->keyAxis()->axisRect()->left()) / (double)(graph->keyAxis()->range().lower - graph->keyAxis()->range().upper);    //ratio px->graph width
  //and result for X-axis
          valueX=-valueX / ratio + graph->keyAxis()->range().lower;
  
  
          qDebug()<<"calculated:"<<valueX<<valueY;
          }
  }
  

  回复于 2024-05-07T02:55:16+08:00