Qt（QVBoxLayout类）何时删除窗口小部件？

Question

I have some simple code to create a new widget using Qt:

Dock::Dock() : QDockWidget() {
    label = new QLabel(QLatin1String("TEST"));

    QVBoxLayout* layout = new QVBoxLayout();
    layout->addWidget(label, 0, Qt::AlignTop);
    layout->addStretch(-1);

    QWidget* multiWidget = new QWidget();
    multiWidget->setLayout(layout);

    setWidget(multiWidget);
}

Where label is a private member QLabel* label . My question is: am I responsible for deleting label in Dock 's destructor?

I tried changing the code so that label is a std::shared_ptr<QLabel> :

Dock::Dock() : QDockWidget() {
    label = std::make_shared<QLabel>(QLatin1String("TEST"));

    QVBoxLayout* layout = new QVBoxLayout();
    layout->addWidget(label.get(), 0, Qt::AlignTop);
    layout->addStretch(-1);

    QWidget* multiWidget = new QWidget();
    multiWidget->setLayout(layout);

    setWidget(multiWidget);
}

So that it is deleted automatically when `Dock' is destroyed but I get an error when I close the program.

Answer 1

In order to properly set up the objects tree you need to do the following:

• Create the container widget first,
• Create child widget and set it's parent,
• Create layout of the container widget,
• Add widget to the layout.

Here is the code that demonstrates the mentioned approach:

Dock::Dock()
  :
    QDockWidget()
{
  QWidget* multiWidget = new QWidget;
  label = new QLabel(QLatin1String("TEST"), multiWidget); // Set parent

  QVBoxLayout* layout = new QVBoxLayout(multiWidget); // Sets layout
  layout->addWidget(label, 0, Qt::AlignTop);
  layout->addStretch(-1);

  setWidget(multiWidget);
}