QT怎么写一个代码QT中鼠标移动到柱状图上的柱子上显示详细信息

以下是一个简单的实现方法，可以在鼠标移动到柱状图上的柱子时显示一个带有柱子值的提示框：

1. 创建一个QChartView对象，并将其设置为窗口的中心控件。

QChartView *chartView = new QChartView(this);
setCentralWidget(chartView);

2. 创建一个QChart对象，并设置其标题和标签。

QChart *chart = new QChart();
chart->setTitle("柱状图");
chart->setAnimationOptions(QChart::AllAnimations);

3. 创建一个QBarSeries对象，并添加一些QBarSet对象。

QBarSeries *series = new QBarSeries();
series->setBarWidth(1);
series->setLabelsVisible(true);

QBarSet *set1 = new QBarSet("Set 1");
*set1 << 10 << 20 << 30 << 40 << 50;
series->append(set1);

QBarSet *set2 = new QBarSet("Set 2");
*set2 << 20 << 30 << 40 << 50 << 60;
series->append(set2);

4. 将QBarSeries对象添加到QChart对象中，并将QChart对象设置为QChartView对象的图表。

chart->addSeries(series);
chart->createDefaultAxes();
chartView->setChart(chart);

5. 为QChartView对象添加一个鼠标移动事件处理函数，该函数根据鼠标的位置计算柱子的值，并将其显示在提示框中。

void ChartView::mouseMoveEvent(QMouseEvent *event)
{
    QPoint pos = event->pos();
    QPointF point = chartView->mapToValue(pos);

    if (series) {
        QBarSet *set = series->barSets()[int(point.x() + 0.5)];
        if (set) {
            QString tooltip = QString("Value: %1").arg(set->at(int(point.y() + 0.5)));
            QToolTip::showText(pos, tooltip, this);
        }
    }
}

6. 在窗口的构造函数中启用鼠标追踪。

setMouseTracking(true);

完整的代码示例：

#include <QtWidgets/QMainWindow>
#include <QtCharts/QChartView>
#include <QtCharts/QBarSeries>
#include <QtCharts/QBarSet>
#include <QtCharts/QValueAxis>
#include <QtCharts/QCategoryAxis>
#include <QMouseEvent>
#include <QToolTip>

QT_CHARTS_USE_NAMESPACE

class ChartView : public QMainWindow
{
    Q_OBJECT

public:
    ChartView(QWidget *parent = nullptr)
        : QMainWindow(parent)
    {
        QChart *chart = new QChart();
        chart->setTitle("柱状图");
        chart->setAnimationOptions(QChart::AllAnimations);

        QBarSeries *series = new QBarSeries();
        series->setBarWidth(1);
        series->setLabelsVisible(true);

        QBarSet *set1 = new QBarSet("Set 1");
        *set1 << 10 << 20 << 30 << 40 << 50;
        series->append(set1);

        QBarSet *set2 = new QBarSet("Set 2");
        *set2 << 20 << 30 << 40 << 50 << 60;
        series->append(set2);

        chart->addSeries(series);
        chart->createDefaultAxes();

        QValueAxis *axisX = qobject_cast<QValueAxis *>(chart->axes(Qt::Horizontal).at(0));
        QCategoryAxis *axisY = qobject_cast<QCategoryAxis *>(chart->axes(Qt::Vertical).at(0));
        axisX->setLabelFormat("%.0f");
        axisX->setTickCount(series->count());
        axisY->setCategories(QStringList() << "A" << "B" << "C" << "D" << "E");

        QChartView *chartView = new QChartView(this);
        chartView->setChart(chart);
        setCentralWidget(chartView);

        series = nullptr;

        setMouseTracking(true);
    }

private:
    void mouseMoveEvent(QMouseEvent *event)
    {
        QPoint pos = event->pos();
        QPointF point = chartView->mapToValue(pos);

        if (series) {
            QBarSet *set = series->barSets()[int(point.x() + 0.5)];
            if (set) {
                QString tooltip = QString("Value: %1").arg(set->at(int(point.y() + 0.5)));
                QToolTip::showText(pos, tooltip, this);
            }
        }
    }

private:
    QChartView *chartView = nullptr;
    QBarSeries *series = nullptr;
};

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    ChartView w;
    w.show();
    return a.exec();
}