如何在QWidget中创建QToolBar？

Question

I am trying to add a QToolBar in a QWidget . But I want its functionality to work as if it was a QMainWindow .

Apparently I can not create QToolBar in a QWidget , and using setAllowedAreas does not work with QWidget : it only works with QMainWindow . Also, my QWidget is in a QMainWindow .

How can I create a QToolBar for my widget?

Answer 1

The allowedAreas property only works when the toolbar is the child of a QMainWindow . You can add the toolbar to a layout, but it won't be movable by the user. You can still relocate it programmatically, however.

To add it to a layout for a fictional class inheriting QWidget :

void SomeWidget::setupWidgetUi()
{
    toolLayout = new QBoxLayout(QBoxLayout::TopToBottom, this);
    //set margins to zero so the toolbar touches the widget's edges
    toolLayout->setContentsMargins(0, 0, 0, 0);

    toolbar = new QToolBar;
    toolLayout->addWidget(toolbar);

    //use a different layout for the contents so it has normal margins
    contentsLayout = new ...
    toolLayout->addLayout(contentsLayout);

    //more initialization here
 }

Changing the toolbar's orientation requires the additional step of calling setDirection on the toolbarLayout , eg:

toolbar->setOrientation(Qt::Vertical);
toolbarLayout->setDirection(QBoxLayout::LeftToRight);
//the toolbar is now on the left side of the widget, oriented vertically

Answer 2

QToolBar is a widget. That's why, you can add a QToolBar to any other widget by calling addWidget for layout or by setting the QToolBar parent to your widget.

As you can see in documentation of QToolBar setAllowedAreas method:

This property holds areas where the toolbar may be placed.

The default is Qt::AllToolBarAreas.

This property only makes sense if the toolbar is in a QMainWindow.

That's why it is impossible to use setAllowedAreas if toolbar is not in QMainWindow.

Answer 3

As far as I know, the only way to properly use the toolbar is with the QMainWindow .

If you want to use the full functionality of the toolbar, create a mainwindow with the window flag Widget . This way you can add it inside some other widget without having it displayed as a new window:

class MyWidget : QMainWindow
{
public:
    MyWidget(QWidget *parent);
    //...

    void addToolbar(QToolBar *toolbar);

private:
    QMainWindow *subMW;
}

MyWidget::MyWidget(QWidget *parent)
    QMainWindow(parent)
{
    subMW = new QMainWindow(this, Qt::Widget);//this is the important part. You will have a mainwindow inside your mainwindow
    setCentralWidget(QWidget *parent);
}

void MyWidget::addToolbar(QToolBar *toolbar)
{
    subMW->addToolBar(toolbar);
}