点击QChart图例，显示或隐藏 对应的折线

// 设置图表的主题m_chart->setTheme(QChart::ChartThemeBlueNcs);QLegend *legend = m_chart->legend();legend->setAlignment(Qt::AlignTop);  // 设置图例的位置为底部legend->setVisible(true);               // 显示图例legend->setBorderColor(Qt::black);      // 设置图例边框颜色// 显示或隐藏图例对应的折线foreach (QLegendMarker *marker, legend->markers()){connect(marker,&QLegendMarker::clicked,this,[&](){qDebug() <<"点击图例:";// 将发送者强制转换为 QLegendMarker 类型QLegendMarker* marker = qobject_cast<QLegendMarker*>(sender());// 检查标记的类型switch (marker->type()){case QLegendMarker::LegendMarkerTypeXY:{// 切换数据系列的可见性marker->series()->setVisible(!marker->series()->isVisible());// 设置标记可见marker->setVisible(true);// 根据数据系列的可见性设置标记的透明度qreal alpha = 1.0;if (!marker->series()->isVisible())alpha = 0.5;// 调整标记的标签刷颜色透明度
                QColor color;QBrush brush = marker->labelBrush();color = brush.color();color.setAlphaF(alpha);brush.setColor(color);marker->setLabelBrush(brush);// 调整标记的刷颜色透明度brush = marker->brush();color = brush.color();color.setAlphaF(alpha);brush.setColor(color);marker->setBrush(brush);// 调整标记的画笔颜色透明度QPen pen = marker->pen();color = pen.color();color.setAlphaF(alpha);pen.setColor(color);marker->setPen(pen);break;}default:break;}});}