QStackedLayout Class Reference

#include <qstackedlayout.h>

Inheritance diagram for QStackedLayout:

[legend]Collaboration diagram for QStackedLayout:

[legend]List of all members.

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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:

snippets/qstackedlayout/main.cpp firstPageWidget QComboBox

QVBoxLayout QVBoxLayout mainLayout->addLayout setLayout

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:

snippets/qstackedlayout/main.cpp QComboBox SLOT

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, QTabWidget

Definition at line 35 of file qstackedlayout.h.

Public Slots
void	setCurrentIndex (int index)
void	setCurrentWidget (QWidget *w)
Signals
void	widgetRemoved (int index)
void	currentChanged (int index)
Public Member Functions
	QStackedLayout ()
	QStackedLayout (QWidget *parent)
	QStackedLayout (QLayout *parentLayout)
	~QStackedLayout ()
int	addWidget (QWidget *w)
int	insertWidget (int index, QWidget *w)
QWidget *	currentWidget () const
int	currentIndex () const
QWidget *	widget (int) const
int	count () const
void	addItem (QLayoutItem *item)
QSize	sizeHint () const
QSize	minimumSize () const
QLayoutItem *	itemAt (int) const
QLayoutItem *	takeAt (int)
void	setGeometry (const QRect &rect)

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Constructor & Destructor 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(), insertWidget()

Definition at line 125 of file qstackedlayout.cpp.

    : QLayout(*new QStackedLayoutPrivate, 0, 0)
{
}

QStackedLayout::QStackedLayout

(

QWidget *

parent

)

[explicit]

Constructs a new QStackedLayout with the given parent.

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

Definition at line 136 of file qstackedlayout.cpp.

    : QLayout(*new QStackedLayoutPrivate, 0, parent)
{
}

QStackedLayout::QStackedLayout

(

QLayout *

parentLayout

)

[explicit]

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

Definition at line 145 of file qstackedlayout.cpp.

    : QLayout(*new QStackedLayoutPrivate, parentLayout, 0)
{
}

QStackedLayout::~QStackedLayout

(

)

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

Definition at line 154 of file qstackedlayout.cpp.

References d, and qDeleteAll().

{
    Q_D(QStackedLayout);
    qDeleteAll(d->list);
}

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Member Function Documentation

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(), setCurrentWidget()

Reimplemented from QLayout.

Definition at line 169 of file qstackedlayout.cpp.

References d, insertWidget(), and QLayoutItem::widget().

Referenced by addItem().

{
    Q_D(QStackedLayout);
    return insertWidget(d->list.count(), widget);
}

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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(), setCurrentWidget()

Definition at line 189 of file qstackedlayout.cpp.

References QLayout::addChildWidget(), d, QWidget::hide(), QLayout::invalidate(), QWidget::lower(), qMin(), setCurrentIndex(), and QLayoutItem::widget().

Referenced by addWidget().

{
    Q_D(QStackedLayout);
    addChildWidget(widget);
    index = qMin(index, d->list.count());
    if (index < 0)
        index = d->list.count();
    QWidgetItem *wi = new QWidgetItem(widget);
    d->list.insert(index, wi);
    invalidate();
    if (d->index < 0) {
        setCurrentIndex(index);
    } else {
        if (index <= d->index)
            ++d->index;
        widget->hide();
        widget->lower();
    }
    return index;
}

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QWidget * QStackedLayout::currentWidget

(

)

const

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

See also:

currentIndex(), setCurrentWidget()

Definition at line 349 of file qstackedlayout.cpp.

References d.

Referenced by setCurrentIndex(), and setGeometry().

{
    Q_D(const QStackedLayout);
    return d->index >= 0 ? d->list.at(d->index)->widget() : 0;
}

int QStackedLayout::currentIndex

(

)

const

Definition at line 317 of file qstackedlayout.cpp.

References d.

{
    Q_D(const QStackedLayout);
    return d->index;
}

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(), indexOf()

Definition at line 361 of file qstackedlayout.cpp.

References d.

{
    Q_D(const QStackedLayout);
     if (index < 0 || index >= d->list.size())
        return 0;
    return d->list.at(index)->widget();
}

int QStackedLayout::count

(

)

const [virtual]

Must be implemented in subclasses to return the number of items in the layout.

See also:

itemAt()

Implements QLayout.

Definition at line 375 of file qstackedlayout.cpp.

References d.

{
    Q_D(const QStackedLayout);
    return d->list.size();
}

void QStackedLayout::addItem

(

QLayoutItem *

item

)

[virtual]

Implements QLayout.

Definition at line 385 of file qstackedlayout.cpp.

References addWidget(), qWarning(), and QLayoutItem::widget().

{
    QWidget *widget = item->widget();
    if (widget) {
        addWidget(widget);
        delete item;
    } else {
        qWarning("QStackedLayout::addItem: Only widgets can be added");
    }
}

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QSize QStackedLayout::sizeHint

(

)

const [virtual]

Implements QLayoutItem.

Definition at line 399 of file qstackedlayout.cpp.

References d, i, n, s, QWidget::sizeHint(), and QLayoutItem::widget().

{
    Q_D(const QStackedLayout);
    QSize s(0, 0);
    int n = d->list.count();

    for (int i = 0; i < n; ++i)
        if (QWidget *widget = d->list.at(i)->widget())
            s = s.expandedTo(widget->sizeHint());
    return s;
}

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QSize QStackedLayout::minimumSize

(

)

const [virtual]

Reimplemented from QLayout.

Definition at line 414 of file qstackedlayout.cpp.

References d, i, n, qSmartMinSize(), s, and QLayoutItem::widget().

{
    Q_D(const QStackedLayout);
    QSize s(0, 0);
    int n = d->list.count();

    for (int i = 0; i < n; ++i)
        if (QWidget *widget = d->list.at(i)->widget())
            s = s.expandedTo(qSmartMinSize(widget));
    return s;
}

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QLayoutItem * QStackedLayout::itemAt

(

int

index

)

const [virtual]

Implements QLayout.

Definition at line 213 of file qstackedlayout.cpp.

References d.

{
    Q_D(const QStackedLayout);
    return d->list.value(index);
}

QLayoutItem * QStackedLayout::takeAt

(

int

index

)

[virtual]

Implements QLayout.

Definition at line 235 of file qstackedlayout.cpp.

References d, emit, QWidget::hide(), qt_wasDeleted(), setCurrentIndex(), QLayoutItem::widget(), and widgetRemoved().

{
    Q_D(QStackedLayout);
    if (index <0 || index >= d->list.size())
        return 0;
    QLayoutItem *item = d->list.takeAt(index);
    if (index == d->index) {
        d->index = -1;
        if ( d->list.count() > 0 ) {
            int newIndex = (index == d->list.count()) ? index-1 : index;
            setCurrentIndex(newIndex);
        }
    } else if (index < d->index) {
        --d->index;
    }
    emit widgetRemoved(index);
    if (item->widget() && !qt_wasDeleted(item->widget()))
        item->widget()->hide();
    return item;
}

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void QStackedLayout::setGeometry

(

const QRect &

rect

)

[virtual]

Implements QLayout.

Definition at line 429 of file qstackedlayout.cpp.

References currentWidget(), QWidget::setGeometry(), and QLayoutItem::widget().

{
    QWidget *widget = currentWidget();
    if (widget)
        widget->setGeometry(rect);
}

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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()

Referenced by takeAt().

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.

See also:

currentWidget(), setCurrentWidget()

Referenced by setCurrentIndex().

void QStackedLayout::setCurrentIndex

(

int

index

)

[slot]

Definition at line 264 of file qstackedlayout.cpp.

References currentChanged(), currentWidget(), d, emit, QWidget::hide(), i, QWidget::isAncestorOf(), next, QObject::parent(), QLayout::parentWidget(), QWidget::setFocus(), Qt::TabFocus, and QLayoutItem::widget().

Referenced by insertWidget(), setCurrentWidget(), and takeAt().

{
    Q_D(QStackedLayout);
    QWidget *prev = currentWidget();
    QWidget *next = widget(index);
    if (!next || next == prev)
        return;

    bool reenableUpdates = false;
    QWidget *parent = parentWidget();

    if (parent && parent->updatesEnabled()) {
        reenableUpdates = true;
        parent->setUpdatesEnabled(false);
    }

    d->index = index;
    next->raise();
    next->show();

    // try to move focus onto the incoming widget if focus
    // was somewhere on the outgoing widget.

    if (parent) {
        QWidget * fw = parent->window()->focusWidget();
        if (fw && (prev && prev->isAncestorOf(fw))) { // focus was on old page
            // look for the best focus widget we can find
            if (QWidget *nfw = next->focusWidget())
                nfw->setFocus();
            else {
                // second best: first child widget in the focus chain
                QWidget *i = fw;
                while ((i = i->nextInFocusChain()) != fw) {
                    if (((i->focusPolicy() & Qt::TabFocus) == Qt::TabFocus)
                        && !i->focusProxy() && i->isVisibleTo(next) && i->isEnabled()
                        && next->isAncestorOf(i)) {
                        i->setFocus();
                        break;
                    }
                }
                // third best: incoming widget
                if (i == fw )
                    next->setFocus();
            }
        }
    }
    if (prev)
        prev->hide();
    if (reenableUpdates)
        parent->setUpdatesEnabled(true);
    emit currentChanged(index);
}

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(), currentWidget()

Definition at line 332 of file qstackedlayout.cpp.

References index, QLayout::indexOf(), qWarning(), setCurrentIndex(), and QLayoutItem::widget().

{
    int index = indexOf(widget);
  if (index == -1) {
    qWarning("QStackedLayout::setCurrentWidget: widget %p not contained in stack", widget);
    return;
  }
    setCurrentIndex(index);
}

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The documentation for this class was generated from the following files:

• src/gui/kernel/qstackedlayout.h
• src/gui/kernel/qstackedlayout.cpp

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