c++ - Qt 中的右键单击事件以打开上下文菜单

Question

我有一段代码调用 mousePressEvent。我有左键单击输出光标的坐标，我有右键单击做同样的事情，但我也想让右键单击打开一个上下文菜单。我到目前为止的代码是:

void plotspace::mousePressEvent(QMouseEvent*event)
{
    double trange = _timeonright - _timeonleft;
    int twidth = width();
    double tinterval = trange/twidth;

    int xclicked = event->x();

    _xvaluecoordinate = _timeonleft+tinterval*xclicked;



    double fmax = Data.plane(X,0).max();
    double fmin = Data.plane(X,0).min();
    double fmargin = (fmax-fmin)/40;
    int fheight = height();
    double finterval = ((fmax-fmin)+4*fmargin)/fheight;

    int yclicked = event->y();

    _yvaluecoordinate = (fmax+fmargin)-finterval*yclicked;

    cout<<"Time(s): "<<_xvaluecoordinate<<endl;
    cout<<"Flux: "<<_yvaluecoordinate<<endl;
    cout << "timeonleft= " << _timeonleft << "\n";

    returncoordinates();

    emit updateCoordinates();

    if (event->button()==Qt::RightButton)
    {
            contextmenu->setContextMenuPolicy(Qt::CustomContextMenu);

            connect(contextmenu, SIGNAL(customContextMenuRequested(const QPoint&)),
            this, SLOT(ShowContextMenu(const QPoint&)));

            void A::ShowContextMenu(const QPoint &pos) 
            {
                QMenu *menu = new QMenu;
                menu->addAction(tr("Remove Data Point"), this,  
                SLOT(test_slot()));

                menu->exec(w->mapToGlobal(pos));
            }

    }   

}

我知道我的问题本质上是非常基本的，并且没有正确声明“上下文菜单”。我从许多来源拼凑了这段代码，但不知道如何在 C++ 中声明一些东西。任何建议将不胜感激。

Answer 1

customContextMenuRequested 在小部件的 contextMenuPolicy 为 Qt::CustomContextMenu 时发出，并且用户已请求小部件上的上下文菜单。因此，在您的小部件的构造函数中，您可以调用 setContextMenuPolicy 并将 customContextMenuRequested 连接到插槽以制作自定义上下文菜单。

在plotspace的构造函数中:

this->setContextMenuPolicy(Qt::CustomContextMenu);

connect(this, SIGNAL(customContextMenuRequested(const QPoint &)), 
        this, SLOT(ShowContextMenu(const QPoint &)));

ShowContextMenu 插槽应该是 plotspace 的类成员，例如:

void plotspace::ShowContextMenu(const QPoint &pos) 
{
   QMenu contextMenu(tr("Context menu"), this);

   QAction action1("Remove Data Point", this);
   connect(&action1, SIGNAL(triggered()), this, SLOT(removeDataPoint()));
   contextMenu.addAction(&action1);

   contextMenu.exec(mapToGlobal(pos));
}