The QAbstractItemDelegate class is used to display and edit data items from a model. More...

#include <qabstractitemdelegate.h>

Inheritance diagram for QAbstractItemDelegate:

Collaboration diagram for QAbstractItemDelegate:

Public Types
enum	EndEditHint { NoHint , EditNextItem , EditPreviousItem , SubmitModelCache , RevertModelCache }
	This enum describes the different hints that the delegate can give to the model and view components to make editing data in a model a comfortable experience for the user. More...

Signals
void	commitData (QWidget *editor)
	This signal must be emitted when the editor widget has completed editing the data, and wants to write it back into the model.

void	closeEditor (QWidget *editor, QAbstractItemDelegate::EndEditHint hint=NoHint)
	This signal is emitted when the user has finished editing an item using the specified editor.

void	sizeHintChanged (const QModelIndex &)

Signals inherited from QObject
void	destroyed (QObject *=nullptr)
	This signal is emitted immediately before the object obj is destroyed, after any instances of QPointer have been notified, and cannot be blocked.

void	objectNameChanged (const QString &objectName, QPrivateSignal)
	This signal is emitted after the object's name has been changed.

Public Member Functions
	QAbstractItemDelegate (QObject *parent=nullptr)
	Creates a new abstract item delegate with the given parent.

virtual	~QAbstractItemDelegate ()
	Destroys the abstract item delegate.

virtual void	paint (QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const =0
	This pure abstract function must be reimplemented if you want to provide custom rendering.

virtual QSize	sizeHint (const QStyleOptionViewItem &option, const QModelIndex &index) const =0
	This pure abstract function must be reimplemented if you want to provide custom rendering.

virtual QWidget *	createEditor (QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const
	Returns the editor to be used for editing the data item with the given index.

virtual void	destroyEditor (QWidget *editor, const QModelIndex &index) const
	Called when the editor is no longer needed for editing the data item with the given index and should be destroyed.

virtual void	setEditorData (QWidget *editor, const QModelIndex &index) const
	Sets the contents of the given editor to the data for the item at the given index.

virtual void	setModelData (QWidget editor, QAbstractItemModel model, const QModelIndex &index) const
	Sets the data for the item at the given index in the model to the contents of the given editor.

virtual void	updateEditorGeometry (QWidget *editor, const QStyleOptionViewItem &option, const QModelIndex &index) const
	Updates the geometry of the editor for the item with the given index, according to the rectangle specified in the option.

virtual bool	editorEvent (QEvent event, QAbstractItemModel model, const QStyleOptionViewItem &option, const QModelIndex &index)
	When editing of an item starts, this function is called with the event that triggered the editing, the model, the index of the item, and the option used for rendering the item.

virtual bool	helpEvent (QHelpEvent event, QAbstractItemView view, const QStyleOptionViewItem &option, const QModelIndex &index)

virtual QList< int >	paintingRoles () const

Public Member Functions inherited from QObject
Q_INVOKABLE	QObject (QObject *parent=nullptr)
	Constructs an object with parent object parent.

virtual	~QObject ()
	Destroys the object, deleting all its child objects.

virtual bool	event (QEvent *event)
	This virtual function receives events to an object and should return true if the event e was recognized and processed.

virtual bool	eventFilter (QObject watched, QEvent event)
	Filters events if this object has been installed as an event filter for the watched object.

QString	objectName () const

Q_WEAK_OVERLOAD void	setObjectName (const QString &name)
	Sets the object's name to name.

void	setObjectName (QAnyStringView name)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

QBindable< QString >	bindableObjectName ()

bool	isWidgetType () const
	Returns `true` if the object is a widget; otherwise returns `false`.

bool	isWindowType () const
	Returns `true` if the object is a window; otherwise returns `false`.

bool	isQuickItemType () const
	Returns `true` if the object is a QQuickItem; otherwise returns `false`.

bool	signalsBlocked () const noexcept
	Returns `true` if signals are blocked; otherwise returns `false`.

bool	blockSignals (bool b) noexcept
	If block is true, signals emitted by this object are blocked (i.e., emitting a signal will not invoke anything connected to it).

QThread *	thread () const
	Returns the thread in which the object lives.

bool	moveToThread (QThread *thread QT6_DECL_NEW_OVERLOAD_TAIL)
	Changes the thread affinity for this object and its children and returns `true` on success.

int	startTimer (int interval, Qt::TimerType timerType=Qt::CoarseTimer)
	This is an overloaded function that will start a timer of type timerType and a timeout of interval milliseconds.

int	startTimer (std::chrono::nanoseconds time, Qt::TimerType timerType=Qt::CoarseTimer)

void	killTimer (int id)
	Kills the timer with timer identifier, id.

void	killTimer (Qt::TimerId id)

template<typename T >
T	findChild (QAnyStringView aName, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	Returns the child of this object that can be cast into type T and that is called name, or \nullptr if there is no such object.

template<typename T >
QList< T >	findChildren (QAnyStringView aName, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	Returns all children of this object with the given name that can be cast to type T, or an empty list if there are no such objects.

template<typename T >
T	findChild (Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

template<typename T >
QList< T >	findChildren (Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

const QObjectList &	children () const
	Returns a list of child objects.

void	setParent (QObject *parent)
	Makes the object a child of parent.

void	installEventFilter (QObject *filterObj)
	Installs an event filter filterObj on this object.

void	removeEventFilter (QObject *obj)
	Removes an event filter object obj from this object.

QMetaObject::Connection	connect (const QObject sender, const char signal, const char *member, Qt::ConnectionType type=Qt::AutoConnection) const

bool	disconnect (const char signal=nullptr, const QObject receiver=nullptr, const char *member=nullptr) const

bool	disconnect (const QObject receiver, const char member=nullptr) const

void	dumpObjectTree () const
	Dumps a tree of children to the debug output.

void	dumpObjectInfo () const
	Dumps information about signal connections, etc.

bool	setProperty (const char *name, const QVariant &value)
	Sets the value of the object's name property to value.

bool	setProperty (const char *name, QVariant &&value)

QVariant	property (const char *name) const
	Returns the value of the object's name property.

QList< QByteArray >	dynamicPropertyNames () const

QBindingStorage *	bindingStorage ()

const QBindingStorage *	bindingStorage () const

QObject *	parent () const
	Returns a pointer to the parent object.

bool	inherits (const char *classname) const
	Returns `true` if this object is an instance of a class that inherits className or a QObject subclass that inherits className; otherwise returns `false`.

Protected Member Functions
	QAbstractItemDelegate (QObjectPrivate &, QObject *parent=nullptr)

Protected Member Functions inherited from QObject
QObject *	sender () const
	Returns a pointer to the object that sent the signal, if called in a slot activated by a signal; otherwise it returns \nullptr.

int	senderSignalIndex () const

int	receivers (const char *signal) const
	Returns the number of receivers connected to the signal.

bool	isSignalConnected (const QMetaMethod &signal) const

virtual void	timerEvent (QTimerEvent *event)
	This event handler can be reimplemented in a subclass to receive timer events for the object.

virtual void	childEvent (QChildEvent *event)
	This event handler can be reimplemented in a subclass to receive child events.

virtual void	customEvent (QEvent *event)
	This event handler can be reimplemented in a subclass to receive custom events.

virtual void	connectNotify (const QMetaMethod &signal)

virtual void	disconnectNotify (const QMetaMethod &signal)

	QObject (QObjectPrivate &dd, QObject *parent=nullptr)

Additional Inherited Members
Public Slots inherited from QObject
void	deleteLater ()
	\threadsafe

Static Public Member Functions inherited from QObject
static QMetaObject::Connection	connect (const QObject sender, const char signal, const QObject receiver, const char member, Qt::ConnectionType=Qt::AutoConnection)
	\threadsafe

static QMetaObject::Connection	connect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &method, Qt::ConnectionType type=Qt::AutoConnection)

template<typename Func1 , typename Func2 >
static QMetaObject::Connection	connect (const typename QtPrivate::FunctionPointer< Func1 >::Object sender, Func1 signal, const typename QtPrivate::ContextTypeForFunctor< Func2 >::ContextType context, Func2 &&slot, Qt::ConnectionType type=Qt::AutoConnection)

template<typename Func1 , typename Func2 >
static QMetaObject::Connection	connect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, Func2 &&slot)

static bool	disconnect (const QObject sender, const char signal, const QObject receiver, const char member)
	\threadsafe

static bool	disconnect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &member)

static bool	disconnect (const QMetaObject::Connection &)
	Disconnect a connection.

template<typename Func1 , typename Func2 >
static bool	disconnect (const typename QtPrivate::FunctionPointer< Func1 >::Object sender, Func1 signal, const typename QtPrivate::FunctionPointer< Func2 >::Object receiver, Func2 slot)

template<typename Func1 >
static bool	disconnect (const typename QtPrivate::FunctionPointer< Func1 >::Object sender, Func1 signal, const QObject receiver, void **zero)

Protected Attributes inherited from QObject
QScopedPointer< QObjectData >	d_ptr

Properties inherited from QObject
QString	objectName
	the name of this object

Related Symbols inherited from QObject
template< class T > T	qobject_cast (const QObject *object)
	Returns the given object cast to type T if the object is of type T (or of a subclass); otherwise returns \nullptr.

template< typename T > T	qFindChildqFindChildren (const QObject *obj, const QString &name)()

template< typename T > QList< T >	qFindChildrenqFindChildren (const QObject *obj, const QString &name)()

	QObjectList
	\macro Q_CLASSINFO(Name, Value)

Detailed Description

The QAbstractItemDelegate class is used to display and edit data items from a model.

\inmodule QtWidgets

A QAbstractItemDelegate provides the interface and common functionality for delegates in the model/view architecture. Delegates display individual items in views, and handle the editing of model data.

The QAbstractItemDelegate class is one of the \l{Model/View Classes} and is part of Qt's \l{Model/View Programming}{model/view framework}.

To render an item in a custom way, you must implement paint() and sizeHint(). The QStyledItemDelegate class provides default implementations for these functions; if you do not need custom rendering, subclass that class instead.

We give an example of drawing a progress bar in items; in our case for a package management program.

We create the WidgetDelegate class, which inherits from QStyledItemDelegate. We do the drawing in the paint() function:

void WidgetDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option,
                           const QModelIndex &index) const
{
    if (index.column() == 1) {
        int progress = index.data().toInt();
 
        QStyleOptionProgressBar progressBarOption;
        progressBarOption.rect = option.rect;
        progressBarOption.minimum = 0;
        progressBarOption.maximum = 100;
        progressBarOption.progress = progress;
        progressBarOption.text = QString::number(progress) + "%";
        progressBarOption.textVisible = true;
 
        QApplication::style()->drawControl(QStyle::CE_ProgressBar,
                                           &progressBarOption, painter);
    } else
        QStyledItemDelegate::paint(painter, option, index);
 

Notice that we use a QStyleOptionProgressBar and initialize its members. We can then use the current QStyle to draw it.

To provide custom editing, there are two approaches that can be used. The first approach is to create an editor widget and display it directly on top of the item. To do this you must reimplement createEditor() to provide an editor widget, setEditorData() to populate the editor with the data from the model, and setModelData() so that the delegate can update the model with data from the editor.

The second approach is to handle user events directly by reimplementing editorEvent().

See also: {model-view-programming}{Model/View Programming}, QStyledItemDelegate, QStyle

Definition at line 22 of file qabstractitemdelegate.h.

Member Enumeration Documentation

◆ EndEditHint

enum QAbstractItemDelegate::EndEditHint

This enum describes the different hints that the delegate can give to the model and view components to make editing data in a model a comfortable experience for the user.

\value NoHint There is no recommended action to be performed.

These hints let the delegate influence the behavior of the view:

\value EditNextItem The view should use the delegate to open an editor on the next item in the view. \value EditPreviousItem The view should use the delegate to open an editor on the previous item in the view.

Note that custom views may interpret the concepts of next and previous differently.

The following hints are most useful when models are used that cache data, such as those that manipulate data locally in order to increase performance or conserve network bandwidth.

\value SubmitModelCache If the model caches data, it should write out cached data to the underlying data store. \value RevertModelCache If the model caches data, it should discard cached data and replace it with data from the underlying data store.

Although models and views should respond to these hints in appropriate ways, custom components may ignore any or all of them if they are not relevant.

Enumerator
NoHint
EditNextItem
EditPreviousItem
SubmitModelCache
RevertModelCache

Definition at line 28 of file qabstractitemdelegate.h.

Constructor & Destructor Documentation

◆ QAbstractItemDelegate() [1/2]

QAbstractItemDelegate::QAbstractItemDelegate ( QObject * parent = nullptr )

explicit

Creates a new abstract item delegate with the given parent.

Definition at line 158 of file qabstractitemdelegate.cpp.

◆ ~QAbstractItemDelegate()

QAbstractItemDelegate::~QAbstractItemDelegate ( )

virtual

Destroys the abstract item delegate.

Definition at line 178 of file qabstractitemdelegate.cpp.

◆ QAbstractItemDelegate() [2/2]

QAbstractItemDelegate::QAbstractItemDelegate	(	QObjectPrivate &	dd,
		QObject *	parent = nullptr )

protected

Creates a new abstract item delegate with the given parent.

Definition at line 169 of file qabstractitemdelegate.cpp.

Member Function Documentation

◆ closeEditor

void QAbstractItemDelegate::closeEditor	(	QWidget *	editor,
		QAbstractItemDelegate::EndEditHint	hint = NoHint )

signal

This signal is emitted when the user has finished editing an item using the specified editor.

The hint provides a way for the delegate to influence how the model and view behave after editing is completed. It indicates to these components what action should be performed next to provide a comfortable editing experience for the user. For example, if EditNextItem is specified, the view should use a delegate to open an editor on the next item in the model.

See also: EndEditHint

Referenced by QDataWidgetMapper::setItemDelegate().

Here is the caller graph for this function:

◆ commitData

void QAbstractItemDelegate::commitData ( QWidget * editor )

signal

This signal must be emitted when the editor widget has completed editing the data, and wants to write it back into the model.

Referenced by QDataWidgetMapper::setItemDelegate().

Here is the caller graph for this function:

◆ createEditor()

QWidget * QAbstractItemDelegate::createEditor	(	QWidget *	parent,
		const QStyleOptionViewItem &	option,
		const QModelIndex &	index ) const

virtual

Returns the editor to be used for editing the data item with the given index.

Note that the index contains information about the model being used. The editor's parent widget is specified by parent, and the item options by option.

The base implementation returns \nullptr. If you want custom editing you will need to reimplement this function.

The returned editor widget should have Qt::StrongFocus; otherwise, \l{QMouseEvent}s received by the widget will propagate to the view. The view's background will shine through unless the editor paints its own background (e.g., with \l{QWidget::}{setAutoFillBackground()}).

See also: destroyEditor(), setModelData(), setEditorData()

Reimplemented in SpinBoxDelegate, QItemDelegate, and QStyledItemDelegate.

Definition at line 220 of file qabstractitemdelegate.cpp.

Referenced by QAbstractItemViewPrivate::editor().

Here is the caller graph for this function:

◆ destroyEditor()

void QAbstractItemDelegate::destroyEditor	(	QWidget *	editor,
		const QModelIndex &	index ) const

virtual

Called when the editor is no longer needed for editing the data item with the given index and should be destroyed.

The default behavior is a call to deleteLater on the editor. It is possible e.g. to avoid this delete by reimplementing this function.

Since: 5.0

See also: createEditor()

Definition at line 237 of file qabstractitemdelegate.cpp.

References Q_UNUSED.

Referenced by QAbstractItemViewPrivate::releaseEditor().

Here is the caller graph for this function:

◆ editorEvent()

bool QAbstractItemDelegate::editorEvent	(	QEvent *	event,
		QAbstractItemModel *	model,
		const QStyleOptionViewItem &	option,
		const QModelIndex &	index )

virtual

When editing of an item starts, this function is called with the event that triggered the editing, the model, the index of the item, and the option used for rendering the item.

Mouse events are sent to editorEvent() even if they don't start editing of the item. This can, for instance, be useful if you wish to open a context menu when the right mouse button is pressed on an item.

The base implementation returns false (indicating that it has not handled the event).

Reimplemented in QItemDelegate, QStyledItemDelegate, and QComboMenuDelegate.

Definition at line 305 of file qabstractitemdelegate.cpp.

Referenced by QAbstractItemViewPrivate::sendDelegateEvent().

Here is the caller graph for this function:

◆ helpEvent()

bool QAbstractItemDelegate::helpEvent	(	QHelpEvent *	event,
		QAbstractItemView *	view,
		const QStyleOptionViewItem &	option,
		const QModelIndex &	index )

virtual

Since: 4.3 Whenever a help event occurs, this function is called with the event view option and the index that corresponds to the item where the event occurs.

Returns true if the delegate can handle the event; otherwise returns false. A return value of true indicates that the data obtained using the index had the required role.

For QEvent::ToolTip and QEvent::WhatsThis events that were handled successfully, the relevant popup may be shown depending on the user's system configuration.

See also: QHelpEvent

Definition at line 329 of file qabstractitemdelegate.cpp.

References d, QObject::inherits(), QString::isEmpty(), QEvent::None, Q_UNUSED, QEvent::QueryWhatsThis, QWhatsThis::showText(), QToolTip::showText(), QEvent::ToolTip, Qt::ToolTipRole, view, QEvent::WhatsThis, and Qt::WhatsThisRole.

Referenced by QAbstractItemView::viewportEvent().

Here is the call graph for this function:

Here is the caller graph for this function:

◆ paint()

void QAbstractItemDelegate::paint	(	QPainter *	painter,
		const QStyleOptionViewItem &	option,
		const QModelIndex &	index ) const

pure virtual

This pure abstract function must be reimplemented if you want to provide custom rendering.

Use the painter and style option to render the item specified by the item index.

If you reimplement this you must also reimplement sizeHint().

Implemented in QCompleterItemDelegate, QColumnViewDelegate, QItemDelegate, QStyledItemDelegate, QtPrivate::QCalendarDelegate, QComboMenuDelegate, QComboBoxDelegate, and QFontFamilyDelegate.

◆ paintingRoles()

QList< int > QAbstractItemDelegate::paintingRoles ( ) const

virtual

This virtual method is reserved and will be used in Qt 5.1.

Definition at line 380 of file qabstractitemdelegate.cpp.

◆ setEditorData()

void QAbstractItemDelegate::setEditorData	(	QWidget *	editor,
		const QModelIndex &	index ) const

virtual

Sets the contents of the given editor to the data for the item at the given index.

Note that the index contains information about the model being used.

The base implementation does nothing. If you want custom editing you will need to reimplement this function.

See also: setModelData()

Reimplemented in SpinBoxDelegate, QItemDelegate, and QStyledItemDelegate.

Definition at line 253 of file qabstractitemdelegate.cpp.

Referenced by QAbstractItemView::dataChanged(), QAbstractItemViewPrivate::editor(), QAbstractItemView::inputMethodEvent(), QDataWidgetMapperPrivate::populate(), and QAbstractItemViewPrivate::updateEditorData().

Here is the caller graph for this function:

◆ setModelData()

void QAbstractItemDelegate::setModelData	(	QWidget *	editor,
		QAbstractItemModel *	model,
		const QModelIndex &	index ) const

virtual

Sets the data for the item at the given index in the model to the contents of the given editor.

The base implementation does nothing. If you want custom editing you will need to reimplement this function.

See also: setEditorData()

Reimplemented in SpinBoxDelegate, QItemDelegate, and QStyledItemDelegate.

Definition at line 268 of file qabstractitemdelegate.cpp.

Referenced by QDataWidgetMapperPrivate::commit(), and QAbstractItemView::commitData().

Here is the caller graph for this function:

◆ sizeHint()

QSize QAbstractItemDelegate::sizeHint	(	const QStyleOptionViewItem &	option,
		const QModelIndex &	index ) const

pure virtual

This pure abstract function must be reimplemented if you want to provide custom rendering.

The options are specified by option and the model item by index.

If you reimplement this you must also reimplement paint().

Implemented in QItemDelegate, QStyledItemDelegate, QComboMenuDelegate, QComboBoxDelegate, and QFontFamilyDelegate.

Referenced by QListViewPrivate::itemSize(), QTreeViewPrivate::paintAlternatingRowColors(), QAbstractItemView::sizeHintForColumn(), QAbstractItemView::sizeHintForIndex(), and QAbstractItemView::sizeHintForRow().

Here is the caller graph for this function:

◆ sizeHintChanged

void QAbstractItemDelegate::sizeHintChanged ( const QModelIndex & index )

signal

Since: 4.4

This signal must be emitted when the sizeHint() of index changed.

Views automatically connect to this signal and relayout items as necessary.

◆ updateEditorGeometry()

void QAbstractItemDelegate::updateEditorGeometry	(	QWidget *	editor,
		const QStyleOptionViewItem &	option,
		const QModelIndex &	index ) const

virtual

Updates the geometry of the editor for the item with the given index, according to the rectangle specified in the option.

If the item has an internal layout, the editor will be laid out accordingly. Note that the index contains information about the model being used.

The base implementation does nothing. If you want custom editing you must reimplement this function.

Reimplemented in SpinBoxDelegate, QItemDelegate, and QStyledItemDelegate.

Definition at line 285 of file qabstractitemdelegate.cpp.

Referenced by QAbstractItemViewPrivate::editor(), and QAbstractItemView::updateEditorGeometries().

Here is the caller graph for this function:

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

qtbase/src/widgets/itemviews/qabstractitemdelegate.h (05fc3aef53348fb58be6308076e000825b704e58)
qtbase/src/widgets/itemviews/qabstractitemdelegate.cpp (faae3dc6b15e3d8754b15a7cfb22b6a797fd2e36)

Public Types

Signals

Public Member Functions

Protected Member Functions

Additional Inherited Members

Detailed Description

Member Enumeration Documentation

◆ EndEditHint

Constructor & Destructor Documentation

◆ QAbstractItemDelegate() [1/2]

◆ ~QAbstractItemDelegate()

◆ QAbstractItemDelegate() [2/2]

Member Function Documentation

◆ closeEditor

◆ commitData

◆ createEditor()

◆ destroyEditor()

◆ editorEvent()

◆ helpEvent()

◆ paint()

◆ paintingRoles()

◆ setEditorData()

◆ setModelData()

◆ sizeHint()

◆ sizeHintChanged

◆ updateEditorGeometry()