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QStackedWidget Class

The QStackedWidget class provides a stack of widgets where only one widget is visible at a time. More...

Header: #include <QStackedWidget>
qmake: QT += widgets
Inherits: QFrame

Properties

Public Functions

QStackedWidget(QWidget *parent = nullptr)
virtual ~QStackedWidget()
int addWidget(QWidget *widget)
int count() const
int currentIndex() const
QWidget *currentWidget() const
int indexOf(QWidget *widget) const
int insertWidget(int index, QWidget *widget)
void removeWidget(QWidget *widget)
QWidget *widget(int index) const

Public Slots

void setCurrentIndex(int index)
void setCurrentWidget(QWidget *widget)

Signals

void currentChanged(int index)
void widgetRemoved(int index)

Reimplemented Protected Functions

virtual bool event(QEvent *e) override

Detailed Description

QStackedWidget can be used to create a user interface similar to the one provided by QTabWidget. It is a convenience layout widget built on top of the QStackedLayout class.

Like QStackedLayout, QStackedWidget can be constructed and populated with a number of child widgets ("pages"):

    QWidget *firstPageWidget = new QWidget;
    QWidget *secondPageWidget = new QWidget;
    QWidget *thirdPageWidget = new QWidget;

    QStackedWidget *stackedWidget = new QStackedWidget;
    stackedWidget->addWidget(firstPageWidget);
    stackedWidget->addWidget(secondPageWidget);
    stackedWidget->addWidget(thirdPageWidget);

    QVBoxLayout *layout = new QVBoxLayout;
    layout->addWidget(stackedWidget);
    setLayout(layout);

QStackedWidget provides no intrinsic means for the user to switch page. This is typically done through a QComboBox or a QListWidget that stores the titles of the QStackedWidget's pages. For example:

    QComboBox *pageComboBox = new QComboBox;
    pageComboBox->addItem(tr("Page 1"));
    pageComboBox->addItem(tr("Page 2"));
    pageComboBox->addItem(tr("Page 3"));
    connect(pageComboBox, QOverload<int>::of(&QComboBox::activated),
            stackedWidget, &QStackedWidget::setCurrentIndex);

When populating a stacked widget, the widgets are added to an internal list. The indexOf() function returns the index of a widget in that list. The widgets can either be added to the end of the list using the addWidget() function, or inserted at a given index using the insertWidget() function. The removeWidget() function removes a widget from the stacked widget. The number of widgets contained in the stacked widget can be obtained using the count() function.

The widget() function returns the widget at a given index position. The index of the widget that is shown on screen is given by currentIndex() and can be changed using setCurrentIndex(). In a similar manner, the currently shown widget can be retrieved using the currentWidget() function, and altered using the setCurrentWidget() function.

Whenever the current widget in the stacked widget changes or a widget is removed from the stacked widget, the currentChanged() and widgetRemoved() signals are emitted respectively.

See also QStackedLayout and QTabWidget.

Property Documentation

count : const int

This property holds the number of widgets contained by this stacked widget

By default, this property contains a value of 0.

Access functions:

int count() const

See also currentIndex() and widget().

currentIndex : int

This property holds the index position of the widget that is visible

The current index is -1 if there is no current widget.

By default, this property contains a value of -1 because the stack is initially empty.

Access functions:

int currentIndex() const
void setCurrentIndex(int index)

Notifier signal:

void currentChanged(int index)

See also currentWidget() and indexOf().

Member Function Documentation

QStackedWidget::QStackedWidget(QWidget *parent = nullptr)

Constructs a QStackedWidget with the given parent.

See also addWidget() and insertWidget().

[signal] void QStackedWidget::currentChanged(int index)

This signal is emitted whenever the current widget changes.

The parameter holds the index of the new current widget, or -1 if there isn't a new one (for example, if there are no widgets in the QStackedWidget).

Note: Notifier signal for property currentIndex.

See also currentWidget() and setCurrentWidget().

[slot] void QStackedWidget::setCurrentWidget(QWidget *widget)

Sets the current widget to be the specified widget. The new current widget must already be contained in this stacked widget.

See also currentWidget() and setCurrentIndex().

[signal] void QStackedWidget::widgetRemoved(int index)

This signal is emitted whenever a widget is removed. The widget's index is passed as parameter.

See also removeWidget().

[virtual] QStackedWidget::~QStackedWidget()

Destroys this stacked widget, and frees any allocated resources.

int QStackedWidget::addWidget(QWidget *widget)

Appends the given widget to the QStackedWidget and returns the index position. Ownership of widget is passed on to the QStackedWidget.

If the QStackedWidget is empty before this function is called, widget becomes the current widget.

See also insertWidget(), removeWidget(), and setCurrentWidget().

QWidget *QStackedWidget::currentWidget() const

Returns the current widget, or nullptr if there are no child widgets.

See also currentIndex() and setCurrentWidget().

[override virtual protected] bool QStackedWidget::event(QEvent *e)

Reimplements: QFrame::event(QEvent *e).

int QStackedWidget::indexOf(QWidget *widget) const

Returns the index of the given widget, or -1 if the given widget is not a child of the QStackedWidget.

See also currentIndex() and widget().

int QStackedWidget::insertWidget(int index, QWidget *widget)

Inserts the given widget at the given index in the QStackedWidget. Ownership of widget is passed on to the QStackedWidget. If index is out of range, the widget is appended (in which case it is the actual index of the widget that is returned).

If the QStackedWidget was empty before this function is called, the given widget becomes the current widget.

Inserting a new widget at an index less than or equal to the current index will increment the current index, but keep the current widget.

See also addWidget(), removeWidget(), and setCurrentWidget().

void QStackedWidget::removeWidget(QWidget *widget)

Removes widget from the QStackedWidget. i.e., widget is not deleted but simply removed from the stacked layout, causing it to be hidden.

Note: Parent object and parent widget of widget will remain the QStackedWidget. If the application wants to reuse the removed widget, then it is recommended to re-parent it.

See also addWidget(), insertWidget(), and currentWidget().

QWidget *QStackedWidget::widget(int index) const

Returns the widget at the given index, or nullptr if there is no such widget.

See also currentWidget() and indexOf().

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