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

#include <qabstractitemdelegate.h>

Inheritance 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...

Public Slots
bool	helpEvent (QHelpEvent event, QAbstractItemView view, const QStyleOptionViewItem &option, const QModelIndex &index)
	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. More...

Public Slots inherited from QObject
void	deleteLater ()
	Schedules this object for deletion. More...

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

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. More...

void	sizeHintChanged (const QModelIndex &)
	This signal must be emitted when the sizeHint() of index changed. More...

Signals inherited from QObject
void	destroyed (QObject *=0)
	This signal is emitted immediately before the object obj is destroyed, and can not be blocked. More...

Public Functions
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. More...

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. More...

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. More...

	QAbstractItemDelegate (QObject *parent=0)
	Creates a new abstract item delegate with the given parent. More...

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. More...

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. More...

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. More...

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. More...

virtual	~QAbstractItemDelegate ()
	Destroys the abstract item delegate. More...

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

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

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

bool	disconnect (const char signal=0, const QObject receiver=0, const char *member=0)

bool	disconnect (const QObject receiver, const char member=0)

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

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

QList< QByteArray >	dynamicPropertyNames () const
	Returns the names of all properties that were dynamically added to the object using setProperty(). More...

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

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

template<typename T >
T	findChild (const QString &aName=QString()) const
	Returns the child of this object that can be cast into type T and that is called name, or 0 if there is no such object. More...

template<typename T >
QList< T >	findChildren (const QString &aName=QString()) 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. More...

template<typename T >
QList< T >	findChildren (const QRegExp &re) const

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. More...

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

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

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

virtual const QMetaObject *	metaObject () const
	Returns a pointer to the meta-object of this object. More...

void	moveToThread (QThread *thread)
	Changes the thread affinity for this object and its children. More...

QString	objectName () const

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

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

Q_INVOKABLE	QObject (QObject *parent=0)
	Constructs an object with parent object parent. More...

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

void	setObjectName (const QString &name)

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

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

void	setUserData (uint id, QObjectUserData *data)

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

int	startTimer (int interval)
	Starts a timer and returns a timer identifier, or returns zero if it could not start a timer. More...

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

QObjectUserData *	userData (uint id) const

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

Static Public Functions
static QString	elidedText (const QFontMetrics &fontMetrics, int width, Qt::TextElideMode mode, const QString &text)
	Use QFontMetrics::elidedText() instead. More...

Static Public Functions inherited from QObject
static bool	connect (const QObject sender, const char signal, const QObject receiver, const char member, Qt::ConnectionType=Qt::AutoConnection)
	Creates a connection of the given type from the signal in the sender object to the method in the receiver object. More...

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

static bool	disconnect (const QObject sender, const char signal, const QObject receiver, const char member)
	Disconnects signal in object sender from method in object receiver. More...

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

static uint	registerUserData ()

static QString	tr (const char sourceText, const char comment=0, int n=-1)

static QString	trUtf8 (const char sourceText, const char comment=0, int n=-1)

Protected Functions
	QAbstractItemDelegate (QObjectPrivate &, QObject *parent=0)
	Creates a new abstract item delegate with the given parent. More...

Protected Functions inherited from QObject
virtual void	childEvent (QChildEvent *)
	This event handler can be reimplemented in a subclass to receive child events. More...

virtual void	connectNotify (const char *signal)
	This virtual function is called when something has been connected to signal in this object. More...

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

virtual void	disconnectNotify (const char *signal)
	This virtual function is called when something has been disconnected from signal in this object. More...

	QObject (QObjectPrivate &dd, QObject *parent=0)

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

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 0. More...

int	senderSignalIndex () const

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

Additional Inherited Members
Static Public Variables inherited from QObject
static const QMetaObject	staticMetaObject
	This variable stores the meta-object for the class. More...

Protected Variables inherited from QObject
QScopedPointer< QObjectData >	d_ptr

Static Protected Variables inherited from QObject
static const QMetaObject	staticQtMetaObject

Related Functions inherited from QObject
T	qFindChildqFindChildren (const QObject *obj, const QString &name)()

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

QList< T >	qFindChildrenqFindChildren (const QObject *obj, const QRegExp &regExp)()

T *	qobject_cast (QObject *object)

	QObjectList

void *	qt_find_obj_child (QObject parent, const char type, const QString &name)
	Returns a pointer to the object named name that inherits type and with a given parent. More...

Detailed Description

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

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 Model/View Classes and is part of Qt's Model/View Programming{model/view framework}.

To render an item in a custom way, you must implement paint() and sizeHint(). The QItemDelegate 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}, QItemDelegate, {Pixelator Example}, QStyledItemDelegate, QStyle

Definition at line 62 of file qabstractitemdelegate.h.

Enumerations

◆ 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.

NoHint There is no recommended action to be performed.

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

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

SubmitModelCache If the model caches data, it should write out cached data to the underlying data store.
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 68 of file qabstractitemdelegate.h.

                      {
         NoHint,
         EditNextItem,
         EditPreviousItem,
         SubmitModelCache,
         RevertModelCache
     };

Constructors and Destructors

◆ QAbstractItemDelegate() [1/2]

QAbstractItemDelegate::QAbstractItemDelegate ( QObject * parent = 0 )

explicit

Creates a new abstract item delegate with the given parent.

Definition at line 184 of file qabstractitemdelegate.cpp.

     : QObject(parent)
 {
 
 }

◆ ~QAbstractItemDelegate()

QAbstractItemDelegate::~QAbstractItemDelegate ( )

virtual

Destroys the abstract item delegate.

Definition at line 207 of file qabstractitemdelegate.cpp.

 {
 
 }

◆ QAbstractItemDelegate() [2/2]

QAbstractItemDelegate::QAbstractItemDelegate	(	QObjectPrivate &	dd,
		QObject *	parent = `0`
	)

protected

Creates a new abstract item delegate with the given parent.

Warning: This function is not part of the public interface.

Definition at line 198 of file qabstractitemdelegate.cpp.

     : QObject(dd, parent)
 {
 
 }

Functions

◆ 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 QStyledItemDelegate::eventFilter(), and QItemDelegate::eventFilter().

◆ 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 QStyledItemDelegate::eventFilter(), and QItemDelegate::eventFilter().

◆ 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 0. If you want custom editing you will need to reimplement this function.

The returned editor widget should have Qt::StrongFocus; otherwise, QMouseEvent 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 QWidget::setAutoFillBackground()).

See also: setModelData() setEditorData()

Reimplemented in QPPDOptionsEditor, QScriptBreakpointsItemDelegate, QScriptDebuggerLocalsItemDelegate, QItemDelegate, and QStyledItemDelegate.

Definition at line 252 of file qabstractitemdelegate.cpp.

Referenced by QAbstractItemViewPrivate::editor().

 {
     return 0;
 }

◆ 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, and QStyledItemDelegate.

Definition at line 321 of file qabstractitemdelegate.cpp.

Referenced by QAbstractItemViewPrivate::sendDelegateEvent().

 {
     // do nothing
     return false;
 }

◆ elidedText()

QString QAbstractItemDelegate::elidedText	(	const QFontMetrics &	fontMetrics,
		int	width,
		Qt::TextElideMode	mode,
		const QString &	text
	)

static

Use QFontMetrics::elidedText() instead.

QFontMetrics fm = ... QString str = QAbstractItemDelegate::elidedText(fm, width, mode, text); QFontMetrics fm = ... QString str = fm.elidedText(text, mode, width);

Definition at line 347 of file qabstractitemdelegate.cpp.

Referenced by QScriptDebuggerLocalsItemDelegate::paint().

 {
     return fontMetrics.elidedText(text, mode, width);
 }

◆ helpEvent

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

slot

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.

Since: 4.3

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 372 of file qabstractitemdelegate.cpp.

 {
     Q_UNUSED(option);
 
     if (!event || !view)
         return false;
     switch (event->type()) {
 #ifndef QT_NO_TOOLTIP
     case QEvent::ToolTip: {
         QHelpEvent *he = static_cast<QHelpEvent*>(event);
         QVariant tooltip = index.data(Qt::ToolTipRole);
         if (tooltip.canConvert<QString>()) {
             QToolTip::showText(he->globalPos(), tooltip.toString(), view);
             return true;
         }
         break;}
 #endif
 #ifndef QT_NO_WHATSTHIS
     case QEvent::QueryWhatsThis: {
         if (index.data(Qt::WhatsThisRole).isValid())
             return true;
         break; }
     case QEvent::WhatsThis: {
         QHelpEvent *he = static_cast<QHelpEvent*>(event);
         QVariant whatsthis = index.data(Qt::WhatsThisRole);
         if (whatsthis.canConvert<QString>()) {
             QWhatsThis::showText(he->globalPos(), whatsthis.toString(), view);
             return true;
         }
         break ; }
 #endif
     default:
         break;
     }
     return false;
 }

◆ 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 QCalendarDelegate, QComboBoxDelegate, QComboMenuDelegate, QScriptDebuggerLocalsItemDelegate, QCompleterItemDelegate, QColumnViewDelegate, QFontFamilyDelegate, QItemDelegate, and QStyledItemDelegate.

◆ 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 QPPDOptionsEditor, QItemDelegate, and QStyledItemDelegate.

Definition at line 269 of file qabstractitemdelegate.cpp.

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

 {
     // do nothing
 }

◆ 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 QPPDOptionsEditor, QScriptBreakpointsItemDelegate, QScriptDebuggerLocalsItemDelegate, QItemDelegate, and QStyledItemDelegate.

Definition at line 284 of file qabstractitemdelegate.cpp.

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

 {
     // do nothing
 }

◆ 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 QComboBoxDelegate, QComboMenuDelegate, QFontFamilyDelegate, QItemDelegate, and QStyledItemDelegate.

Referenced by QListViewPrivate::itemSize(), and QTreeViewPrivate::paintAlternatingRowColors().

◆ sizeHintChanged

void QAbstractItemDelegate::sizeHintChanged ( const QModelIndex & index )

signal

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

Since: 4.4

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 QItemDelegate, and QStyledItemDelegate.

Definition at line 301 of file qabstractitemdelegate.cpp.

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

 {
     // do nothing
 }

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

/src/gui/itemviews/qabstractitemdelegate.h
/src/gui/itemviews/qabstractitemdelegate.cpp

Public Types

Public Slots

Signals

Public Functions

Static Public Functions

Protected Functions

Additional Inherited Members

Detailed Description

Enumerations

◆ EndEditHint

Constructors and Destructors

◆ QAbstractItemDelegate() [1/2]

◆ ~QAbstractItemDelegate()

◆ QAbstractItemDelegate() [2/2]

Functions

◆ closeEditor

◆ commitData

◆ createEditor()

◆ editorEvent()

◆ elidedText()

◆ helpEvent

◆ paint()

◆ setEditorData()

◆ setModelData()

◆ sizeHint()

◆ sizeHintChanged

◆ updateEditorGeometry()