Qt 4.8: QStackedLayout Class Reference

Qt Reference Documentation

# QStackedLayout Class Reference

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

     #include <QStackedLayout>

Inherits: QLayout.

- List of all members, including inherited members

## Public Types

enum | StackingMode { StackOne, StackAll }

## Properties

- count : const int
- currentIndex : int
- stackingMode : StackingMode

- 2 properties inherited from QLayout
- 1 property inherited from QObject

## Public Functions

| QStackedLayout ()
| QStackedLayout ( QWidget * parent )
| QStackedLayout ( QLayout * parentLayout )
| ~QStackedLayout ()
int | addWidget ( QWidget * widget )
int | currentIndex () const
QWidget * | currentWidget () const
int | insertWidget ( int index, QWidget * widget )
void | setStackingMode ( StackingMode stackingMode )
StackingMode | stackingMode () const
QWidget * | widget ( int index ) const

## Reimplemented Public Functions

virtual void | addItem ( QLayoutItem * item )
virtual int | count () const
virtual QLayoutItem * | itemAt ( int index ) const
virtual QSize | minimumSize () const
virtual void | setGeometry ( const QRect & rect )
virtual QSize | sizeHint () const
virtual QLayoutItem * | takeAt ( int index )

- 35 public functions inherited from QLayout
- 29 public functions inherited from QObject
- 17 public functions inherited from QLayoutItem

## Public Slots

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

- 1 public slot inherited from QObject

## Signals

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

- 1 signal inherited from QObject

### Additional Inherited Members

- 1 static public member inherited from QLayout
- 7 static public members inherited from QObject
- 4 protected functions inherited from QLayout
- 8 protected functions inherited from QObject

## Detailed Description

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

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

A QStackedLayout can be populated with a number of child widgets ("pages"). For example:

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

         QStackedLayout *stackedLayout = new QStackedLayout;
         stackedLayout->addWidget(firstPageWidget);
         stackedLayout->addWidget(secondPageWidget);
         stackedLayout->addWidget(thirdPageWidget);

         QVBoxLayout *mainLayout = new QVBoxLayout;
         mainLayout->addLayout(stackedLayout);
         setLayout(mainLayout);

QStackedLayout 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 QStackedLayout'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, SIGNAL(activated(int)),
                 stackedLayout, SLOT(setCurrentIndex(int)));

When populating a layout, 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 the widget at the given index from the layout. The number of widgets contained in the layout, 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 layout changes or a widget is removed from the layout, the currentChanged() and widgetRemoved() signals are emitted respectively.

See also QStackedWidget and QTabWidget.

## Member Type Documentation

### enum QStackedLayout::StackingMode

This enum specifies how the layout handles its child widgets regarding their visibility.

Constant | Value | Description
--- | --- | ---
`QStackedLayout::StackOne` | `0` | Only the current widget is visible. This is the default.
`QStackedLayout::StackAll` | `1` | All widgets are visible. The current widget is merely raised.

This enum was introduced or modified in Qt 4.4.

## Property Documentation

### count : const int

This property holds the number of widgets contained in the layout.

Access functions:

virtual 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.

Access functions:

int | currentIndex () const
void | setCurrentIndex ( int index )

Notifier signal:

void | currentChanged ( int index )

See also currentWidget() and indexOf().

### stackingMode : StackingMode

This property determines the way visibility of child widgets are handled.

The default value is StackOne. Setting the property to StackAll allows you to make use of the layout for overlay widgets that do additional drawing on top of other widgets, for example, graphical editors.

This property was introduced in Qt 4.4.

Access functions:

StackingMode | stackingMode () const
void | setStackingMode ( StackingMode stackingMode )

## Member Function Documentation

### QStackedLayout::QStackedLayout ()

Constructs a QStackedLayout with no parent.

This QStackedLayout must be installed on a widget later on to become effective.

See also addWidget() and insertWidget().

### QStackedLayout::QStackedLayout ( QWidget * parent )

Constructs a new QStackedLayout with the given parent.

This layout will install itself on the parent widget and manage the geometry of its children.

### QStackedLayout::QStackedLayout ( QLayout * parentLayout )

Constructs a new QStackedLayout and inserts it into the given parentLayout.

### QStackedLayout::~QStackedLayout ()

Destroys this QStackedLayout. Note that the layout's widgets are not destroyed.

### void QStackedLayout::addItem ( QLayoutItem * item )`[virtual]`

Reimplemented from QLayout::addItem().

### int QStackedLayout::addWidget ( QWidget * widget )

Adds the given widget to the end of this layout and returns the index position of the widget.

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

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

### void QStackedLayout::currentChanged ( int index )`[signal]`

This signal is emitted whenever the current widget in the layout changes. The index specifies 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 QStackedLayout)

See also currentWidget() and setCurrentWidget().

### QWidget * QStackedLayout::currentWidget () const

Returns the current widget, or 0 if there are no widgets in this layout.

See also currentIndex() and setCurrentWidget().

### int QStackedLayout::insertWidget ( int index, QWidget * widget )

Inserts the given widget at the given index in this QStackedLayout. 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 QStackedLayout is 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().

### QLayoutItem * QStackedLayout::itemAt ( int index ) const`[virtual]`

Reimplemented from QLayout::itemAt().

### QSize QStackedLayout::minimumSize () const`[virtual]`

Reimplemented from QLayoutItem::minimumSize().

### void QStackedLayout::setCurrentWidget ( QWidget * widget )`[slot]`

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

See also setCurrentIndex() and currentWidget().

### void QStackedLayout::setGeometry ( const QRect & rect )`[virtual]`

Reimplemented from QLayoutItem::setGeometry().

### QSize QStackedLayout::sizeHint () const`[virtual]`

Reimplemented from QLayoutItem::sizeHint().

### QLayoutItem * QStackedLayout::takeAt ( int index )`[virtual]`

Reimplemented from QLayout::takeAt().

### QWidget * QStackedLayout::widget ( int index ) const

Returns the widget at the given index, or 0 if there is no widget at the given position.

See also currentWidget() and indexOf().

### void QStackedLayout::widgetRemoved ( int index )`[signal]`

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

See also removeWidget().