按下鼠标中键的qt图表移动视图

Question

我目前正在使用 Qts 图表绘图工具。我现在有一个图，我可以使用 this 示例提供的图表视图 class 进行放大和缩小（稍作调整）。我希望看到不仅可以缩放，还可以通过按下鼠标中键移动我的视图（这在其他应用程序中经常使用，因此非常直观）。

我如何在 Qt 中执行此操作？如果鼠标在按下鼠标中键期间移动，我如何检查鼠标中键是否被按下和释放并更改我在绘图中的视图...

我敢肯定有人以前编写过此代码，非常感谢 example/help。

Answer 1

您需要从 QChartView 派生一个 class 并重载鼠标事件：

class ChartView: public QChartView
{
    Q_OBJECT

public:
    ChartView(Chart* chart, QWidget *parent = 0);

protected:

    virtual void mousePressEvent(QMouseEvent *event) override;
    virtual void mouseMoveEvent(QMouseEvent *event) override;

private:

    QPointF m_lastMousePos;
};

ChartView::ChartView(Chart* chart, QWidget *parent)
    : QChartView(chart, parent)
{
    setDragMode(QGraphicsView::NoDrag);
    this->setMouseTracking(true);
}

void ChartView::mousePressEvent(QMouseEvent *event)
{
    if (event->button() == Qt::MiddleButton)
    {
        QApplication::setOverrideCursor(QCursor(Qt::SizeAllCursor));
        m_lastMousePos = event->pos();
        event->accept();
    }

    QChartView::mousePressEvent(event);
}

void ChartView::mouseMoveEvent(QMouseEvent *event)
{
    // pan the chart with a middle mouse drag
    if (event->buttons() & Qt::MiddleButton)
    {
        QRectF bounds = QRectF(0,0,0,0);
        for(auto series : this->chart()->series())
            bounds.united(series->bounds())

        auto dPos = this->chart()->mapToValue(event->pos()) - this->chart()->mapToValue(m_lastMousePos);

        if (this->rubberBand() == QChartView::RectangleRubberBand)
            this->chart()->zoom(bounds.translated(-dPos.x(), -dPos.y()));
        else if (this->rubberBand() == QChartView::HorizontalRubberBand)
            this->chart()->zoom(bounds.translated(-dPos.x(), 0));
        else if (this->rubberBand() == QChartView::VerticalRubberBand)
            this->chart()->zoom(bounds.translated(0, -dPos.y()));

        m_lastMousePos = event->pos();
        event->accept();
    }

    QChartView::mouseMoveEvent(event);
}

Answer 2

我想提供 Nicolas 的更简单版本 mouseMoveEvent():

    void ChartView::mouseMoveEvent(QMouseEvent *event)
    {
        // pan the chart with a middle mouse drag
        if (event->buttons() & Qt::MiddleButton)
        {
            auto dPos = event->pos() - lastMousePos_;
            chart()->scroll(-dPos.x(), dPos.y());

            lastMousePos_ = event->pos();
            event->accept();

            QApplication::restoreOverrideCursor();
        }

        QChartView::mouseMoveEvent(event);
    }

此外，请务必包含 QApplication::restoreOverrideCursor()，以便移动完成后光标 returns 恢复正常。

按下鼠标中键的qt图表移动视图

qt chart move view with pressed middle mouse button

c++

qt

qtcharts