KViewStateSerializer Class Reference

#include <KViewStateSerializer>

Inheritance diagram for KViewStateSerializer:

Public Member Functions
	KViewStateSerializer (QObject *parent=nullptr)
	~KViewStateSerializer () override
QString	currentIndexKey () const
QStringList	expansionKeys () const
void	restoreCurrentItem (const QString &indexString)
void	restoreExpanded (const QStringList &indexStrings)
void	restoreScrollState (int verticalScoll, int horizontalScroll)
void	restoreSelection (const QStringList &indexStrings)
QPair< int, int >	scrollState () const
QStringList	selectionKeys () const
QItemSelectionModel *	selectionModel () const
void	setSelectionModel (QItemSelectionModel *selectionModel)
void	setView (QAbstractItemView *view)
QAbstractItemView *	view () const
Public Member Functions inherited from QObject
	QObject (QObject *parent)
QBindable< QString >	bindableObjectName ()
bool	blockSignals (bool block)
const QObjectList &	children () const const
QMetaObject::Connection	connect (const QObject *sender, const char *signal, const char *method, Qt::ConnectionType type) const const
void	deleteLater ()
void	destroyed (QObject *obj)
bool	disconnect (const char *signal, const QObject *receiver, const char *method) const const
bool	disconnect (const QObject *receiver, const char *method) const const
void	dumpObjectInfo () const const
void	dumpObjectTree () const const
QList< QByteArray >	dynamicPropertyNames () const const
virtual bool	event (QEvent *e)
virtual bool	eventFilter (QObject *watched, QEvent *event)
T	findChild (const QString &name, Qt::FindChildOptions options) const const
QList< T >	findChildren (const QRegularExpression &re, Qt::FindChildOptions options) const const
QList< T >	findChildren (const QString &name, Qt::FindChildOptions options) const const
QList< T >	findChildren (Qt::FindChildOptions options) const const
bool	inherits (const char *className) const const
void	installEventFilter (QObject *filterObj)
bool	isQuickItemType () const const
bool	isWidgetType () const const
bool	isWindowType () const const
void	killTimer (int id)
virtual const QMetaObject *	metaObject () const const
void	moveToThread (QThread *targetThread)
QString	objectName () const const
void	objectNameChanged (const QString &objectName)
QObject *	parent () const const
QVariant	property (const char *name) const const
	Q_CLASSINFO (Name, Value)
	Q_EMIT Q_EMIT
	Q_ENUM (...)
	Q_ENUM_NS (...)
	Q_ENUMS (...)
	Q_FLAG (...)
	Q_FLAG_NS (...)
	Q_FLAGS (...)
	Q_GADGET Q_GADGET
	Q_GADGET_EXPORT (EXPORT_MACRO)
	Q_INTERFACES (...)
	Q_INVOKABLE Q_INVOKABLE
	Q_MOC_INCLUDE Q_MOC_INCLUDE
	Q_NAMESPACE Q_NAMESPACE
	Q_NAMESPACE_EXPORT (EXPORT_MACRO)
	Q_OBJECT Q_OBJECT
	Q_PROPERTY (...)
	Q_REVISION Q_REVISION
	Q_SET_OBJECT_NAME (Object)
	Q_SIGNAL Q_SIGNAL
	Q_SIGNALS Q_SIGNALS
	Q_SLOT Q_SLOT
	Q_SLOTS Q_SLOTS
T	qobject_cast (const QObject *object)
T	qobject_cast (QObject *object)
	QT_NO_NARROWING_CONVERSIONS_IN_CONNECT QT_NO_NARROWING_CONVERSIONS_IN_CONNECT
void	removeEventFilter (QObject *obj)
void	setObjectName (const QString &name)
void	setObjectName (QAnyStringView name)
void	setParent (QObject *parent)
bool	setProperty (const char *name, const QVariant &value)
bool	setProperty (const char *name, QVariant &&value)
bool	signalsBlocked () const const
int	startTimer (int interval, Qt::TimerType timerType)
int	startTimer (std::chrono::milliseconds interval, Qt::TimerType timerType)
QThread *	thread () const const

Protected Member Functions
virtual QModelIndex	indexFromConfigString (const QAbstractItemModel *model, const QString &key) const =0
virtual QString	indexToConfigString (const QModelIndex &index) const =0
void	restoreState ()
Protected Member Functions inherited from QObject
virtual void	childEvent (QChildEvent *event)
virtual void	connectNotify (const QMetaMethod &signal)
virtual void	customEvent (QEvent *event)
virtual void	disconnectNotify (const QMetaMethod &signal)
bool	isSignalConnected (const QMetaMethod &signal) const const
int	receivers (const char *signal) const const
QObject *	sender () const const
int	senderSignalIndex () const const
virtual void	timerEvent (QTimerEvent *event)

Additional Inherited Members
Properties inherited from QObject
	objectName
Static Public Member Functions inherited from QObject
QMetaObject::Connection	connect (const QObject *sender, const char *signal, const QObject *receiver, const char *method, Qt::ConnectionType type)
QMetaObject::Connection	connect (const QObject *sender, const QMetaMethod &signal, const QObject *receiver, const QMetaMethod &method, Qt::ConnectionType type)
QMetaObject::Connection	connect (const QObject *sender, PointerToMemberFunction signal, const QObject *context, Functor functor, Qt::ConnectionType type)
QMetaObject::Connection	connect (const QObject *sender, PointerToMemberFunction signal, const QObject *receiver, PointerToMemberFunction method, Qt::ConnectionType type)
QMetaObject::Connection	connect (const QObject *sender, PointerToMemberFunction signal, Functor functor)
bool	disconnect (const QMetaObject::Connection &connection)
bool	disconnect (const QObject *sender, const char *signal, const QObject *receiver, const char *method)
bool	disconnect (const QObject *sender, const QMetaMethod &signal, const QObject *receiver, const QMetaMethod &method)
bool	disconnect (const QObject *sender, PointerToMemberFunction signal, const QObject *receiver, PointerToMemberFunction method)
QString	tr (const char *sourceText, const char *disambiguation, int n)
Public Attributes inherited from QObject
typedef	QObjectList

Detailed Description

Object for saving and restoring state in QTreeViews and QItemSelectionModels.

Implement the indexFromConfigString and indexToConfigString methods to handle the model in the view whose state is being saved. These implementations can be quite trivial:

QModelIndex DynamicTreeStateSaver::indexFromConfigString(const QAbstractItemModel* model,
                                                         const QString& key) const
{
    QModelIndexList list = model->match(model->index(0, 0),
                                        DynamicTreeModel::DynamicTreeModelId,
                                        key.toInt(), 1, Qt::MatchRecursive);
    if (list.isEmpty()) {
        return QModelIndex();
    }
    return list.first();
}
 
QString DynamicTreeStateSaver::indexToConfigString(const QModelIndex& index) const
{
    return index.data(DynamicTreeModel::DynamicTreeModelId).toString();
}

It is possible to restore the state of a QTreeView (that is, the expanded state and selected state of all indexes as well as the horizontal and vertical scroll state) by using setTreeView.

If there is no tree view state to restore (for example if using QML), the selection state of a QItemSelectionModel can be saved or restored instead.

The state of any QAbstractScrollArea can also be saved and restored.

A KViewStateSerializer should be created on the stack when saving and on the heap when restoring. The model may be populated dynamically between several event loops, so it may not be immediate for the indexes that should be selected to be in the model. The saver should not be persisted as a member. The saver will destroy itself when it has completed the restoration specified in the config group, or a small amount of time has elapsed.

MyWidget::MyWidget(Qobject *parent)
  : QWidget(parent)
{
    ...
 
    m_view = new QTreeView(splitter);
    m_view->setModel(model);
 
    connect(model, &QAbstractItemModel::modelAboutToBeReset, this, [this]() { saveState(); });
    connect(model, &QAbstractItemModel::modelReset, [this]() { restoreState(); });
    connect(qApp, &QApplication::aboutToQuit, this, [this]() { saveState(); });
 
    restoreState();
}
 
void StateSaverWidget::saveState()
{
    ConcreteStateSaver saver;
    saver.setTreeView(m_view);
 
    KConfigGroup cfg(KSharedConfig::openConfig(), "ExampleViewState");
    saver.saveState(cfg);
    cfg.sync();
}
 
void StateSaverWidget::restoreState()
{
    // Will delete itself.
    ConcreteTreeStateSaver *saver = new ConcreteStateSaver();
    saver->setTreeView(m_view);
    KConfigGroup cfg(KSharedConfig::openConfig(), "ExampleViewState");
    saver->restoreState(cfg);
}

After creating a saver, the state can be saved using a KConfigGroup.

It is also possible to save and restore state directly by using the restoreSelection, restoreExpanded etc methods. Note that the implementation of these methods should return strings that the indexFromConfigString implementation can handle.

class DynamicTreeStateSaver : public KViewStateSerializer
{
    Q_OBJECT
public:
  // ...
 
    void selectItems(const QList<qint64> &items)
    {
        QStringList itemStrings;
        for (qint64 item : items) {
            itemStrings << QString::number(item);
        }
        restoreSelection(itemStrings);
    }
 
    void expandItems(const QList<qint64> &items)
    {
        QStringList itemStrings;
        for (qint64 item : items) {
            itemStrings << QString::number(item);
        }
        restoreSelection(itemStrings);
    }
};

Note that a single instance of this class should be used with only one widget. That is don't do this:

saver->setTreeView(treeView1);
saver->setSelectionModel(treeView2->selectionModel());
saver->setScrollArea(treeView3);

To save the state of 3 different widgets, use three savers, even if they operate on the same root model.

saver1->setTreeView(treeView1);
saver2->setSelectionModel(treeView2->selectionModel());
saver3->setScrollArea(treeView3);

Note

The KViewStateSerializer does not take ownership of any widgets set on it.

It is recommended to restore the state on application startup and after the model has been reset, and to save the state on application close and before the model has been reset.

See also

QAbstractItemModel::modelAboutToBeReset QAbstractItemModel::modelReset

Author

Stephen Kelly steph.nosp@m.en@k.nosp@m.dab.c.nosp@m.om

Since

4.5

Definition at line 168 of file kviewstateserializer.h.

Constructor & Destructor Documentation

KViewStateSerializer()

KViewStateSerializer::KViewStateSerializer ( QObject * parent = nullptr )

explicit

Constructor.

Definition at line 96 of file kviewstateserializer.cpp.

~KViewStateSerializer()

KViewStateSerializer::~KViewStateSerializer ( )

overridedefault

Destructor.

Member Function Documentation

currentIndexKey()

QString KViewStateSerializer::currentIndexKey

(

)

const

Returns a QString describing the current index in the selection model.

Definition at line 307 of file kviewstateserializer.cpp.

expansionKeys()

QStringList KViewStateSerializer::expansionKeys

(

)

const

Returns a QStringList representing the expanded indexes in the QTreeView.

Definition at line 316 of file kviewstateserializer.cpp.

indexFromConfigString()

virtual QModelIndex KViewStateSerializer::indexFromConfigString ( const QAbstractItemModel * model, const QString & key ) const

protectedpure virtual

Reimplement to return an index in the model described by the unique key key.

indexToConfigString()

virtual QString KViewStateSerializer::indexToConfigString ( const QModelIndex & index ) const

protectedpure virtual

Reimplement to return a unique string for the index.

restoreCurrentItem()

void KViewStateSerializer::restoreCurrentItem

(

const QString &

indexString

)

Make the index described by indexString the currentIndex in the selectionModel.

Definition at line 202 of file kviewstateserializer.cpp.

restoreExpanded()

void KViewStateSerializer::restoreExpanded

(

const QStringList &

indexStrings

)

Expand the indexes described by indexStrings in the QTreeView.

Definition at line 236 of file kviewstateserializer.cpp.

restoreScrollState()

void KViewStateSerializer::restoreScrollState	(	int	verticalScoll,
		int	horizontalScroll )

Restores the scroll state of the QAbstractScrollArea to the verticalScoll and horizontalScroll.

Definition at line 255 of file kviewstateserializer.cpp.

restoreSelection()

void KViewStateSerializer::restoreSelection

(

const QStringList &

indexStrings

)

Select the indexes described by indexStrings.

Definition at line 287 of file kviewstateserializer.cpp.

restoreState()

void KViewStateSerializer::restoreState ( )

protected

Definition at line 349 of file kviewstateserializer.cpp.

scrollState()

QPair< int, int > KViewStateSerializer::scrollState

(

)

const

Returns the vertical and horizontal scroll of the QAbstractScrollArea.

Definition at line 343 of file kviewstateserializer.cpp.

selectionKeys()

QStringList KViewStateSerializer::selectionKeys

(

)

const

Returns a QStringList describing the selection in the selectionModel.

Definition at line 326 of file kviewstateserializer.cpp.

selectionModel()

QItemSelectionModel * KViewStateSerializer::selectionModel

(

)

const

The QItemSelectionModel whose state is persisted.

Definition at line 126 of file kviewstateserializer.cpp.

setSelectionModel()

void KViewStateSerializer::setSelectionModel

(

QItemSelectionModel *

selectionModel

)

Sets the QItemSelectionModel whose state is persisted.

Definition at line 132 of file kviewstateserializer.cpp.

setView()

void KViewStateSerializer::setView

(

QAbstractItemView *

view

)

Sets the view whose state is persisted.

Definition at line 106 of file kviewstateserializer.cpp.

view()

QAbstractItemView * KViewStateSerializer::view

(

)

const

The view whose state is persisted.

Definition at line 120 of file kviewstateserializer.cpp.

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

• kviewstateserializer.h
• kviewstateserializer.cpp