The QItemDelegate class provides display and editing facilities for data items from a model. More...

Inheritance diagram for QItemDelegate:

Public Methods
	QItemDelegate (QObject *parent=nullptr)

	~QItemDelegate ()

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

bool	hasClipping () const

QItemEditorFactory *	itemEditorFactory () const

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

void	setClipping (bool enabled)

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

void	setItemEditorFactory (QItemEditorFactory *factory)

void	setModelData (QWidget editor, QAbstractItemModel model, const QModelIndex &index) const override

QSize	sizeHint (const QStyleOptionViewItem &option, const QModelIndex &index) const override

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

Public Methods inherited from QAbstractItemDelegate
	QAbstractItemDelegate (QObject *parent=nullptr)

virtual	~QAbstractItemDelegate ()

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

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

Public Methods inherited from QObject
	QObject (QObject *parent=nullptr)

	~QObject ()

bool	blockSignals (bool block)

const QList< QObject * > &	children () const

bool	connect (const QObject *sender, const QString &signalMethod, const QString &location, const QString &slotMethod, Qt::ConnectionType type=Qt::AutoConnection)

bool	connect (const QObject *sender, const QString &signalMethod, const QString &slotMethod, Qt::ConnectionType type=Qt::AutoConnection)

bool	disconnect (const QObject *receiver, const QString &slotMethod=QString ()) const

bool	disconnect (const QString &signalMethod, const QString &location, const QObject *receiver=nullptr, const QString &slotMethod=QString ()) const

bool	disconnect (const QString &signalMethod=QString (), const QObject *receiver=nullptr, const QString &slotMethod=QString ()) const

void	dumpObjectInfo ()

void	dumpObjectTree ()

QList< QString >	dynamicPropertyNames () const

virtual bool	event (QEvent *event)

template<typename T >
T	findChild (const QString &childName=QString ()) const

template<class T >
QList< T >	findChildren (const QRegularExpression &regExp, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const

template<class T >
QList< T >	findChildren (const QString &childName=QString (), Qt::FindChildOptions options=Qt::FindChildrenRecursively) const

bool	inherits (const QString &className) const

void	installEventFilter (QObject *filterObj)

bool	isWidgetType () const

bool	isWindowType () const

void	killTimer (int id)

const QMetaObject *	metaObject () const

void	moveToThread (QThread *targetThread)

QString	objectName () const

QObject *	parent () const

template<class T = QVariant>
T	property (const QString &name) const

void	removeEventFilter (QObject *obj)

void	setObjectName (const QString &name)

void	setParent (QObject *parent)

bool	setProperty (const QString &name, const QVariant &value)

bool	signalsBlocked () const

int	startTimer (int interval, Qt::TimerType timerType=Qt::CoarseTimer)

QThread *	thread () const

Protected Methods
void	drawBackground (QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const

virtual void	drawCheck (QPainter *painter, const QStyleOptionViewItem &option, const QRect &rect, Qt::CheckState state) const

virtual void	drawDecoration (QPainter *painter, const QStyleOptionViewItem &option, const QRect &rect, const QPixmap &pixmap) const

virtual void	drawDisplay (QPainter *painter, const QStyleOptionViewItem &option, const QRect &rect, const QString &text) const

virtual void	drawFocus (QPainter *painter, const QStyleOptionViewItem &option, const QRect &rect) const

bool	editorEvent (QEvent event, QAbstractItemModel model, const QStyleOptionViewItem &option, const QModelIndex &index) override

bool	eventFilter (QObject object, QEvent event) override

Protected Methods inherited from QObject
virtual void	childEvent (QChildEvent *event)

virtual void	connectNotify (const QMetaMethod &signalMethod) const

virtual void	customEvent (QEvent *event)

virtual void	disconnectNotify (const QMetaMethod &signalMethod) const

bool	isSignalConnected (const QMetaMethod &signalMethod) const

int	receivers (const QString &signal) const

QObject *	sender () const

int	senderSignalIndex () const

virtual void	timerEvent (QTimerEvent *event)

Properties
	clipping

Properties inherited from QObject
	objectName

Additional Inherited Members
Public Types inherited from QAbstractItemDelegate
enum	EndEditHint

Public Signals inherited from QAbstractItemDelegate
void	closeEditor (QWidget *editor, QAbstractItemDelegate::EndEditHint hint=NoHint)

void	commitData (QWidget *editor)

void	sizeHintChanged (const QModelIndex &index)

Public Signals inherited from QObject
void	destroyed (QObject *obj=nullptr)

void	objectNameChanged (const QString &objectName)

Public Slots inherited from QObject
void	deleteLater ()

Static Public Methods inherited from QAbstractItemDelegate
static QString	elidedText (const QFontMetrics &fontMetrics, int width, Qt::TextElideMode mode, const QString &text)

Static Public Methods inherited from QObject
static bool	connect (const QObject sender, const QMetaMethod &signalMethod, const QObject receiver, const QMetaMethod &slotMethod, Qt::ConnectionType type=Qt::AutoConnection)

static bool	connect (const QObject sender, const QString &signalMethod, const QObject receiver, const QString &slotMethod, Qt::ConnectionType type=Qt::AutoConnection, const QString &location=QString ())

static bool	connect (const QObject sender, const QString &signalMethod, const QString &location, const QObject receiver, const QString &slotMethod, Qt::ConnectionType type=Qt::AutoConnection)

template<class Sender , class SignalClass , class... SignalArgs, class Receiver , class SlotClass , class... SlotArgs, class SlotReturn >
static bool	connect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver receiver, SlotReturn (SlotClass::slotMethod)(SlotArgs...), Qt::ConnectionType type=Qt::AutoConnection)

template<class Sender , class SignalClass , class... SignalArgs, class Receiver , class T >
static bool	connect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver *receiver, T slotLambda, Qt::ConnectionType type=Qt::AutoConnection)

static bool	disconnect (const QObject sender, const QMetaMethod &signalMethod, const QObject receiver, const QMetaMethod &slotMethod)

static bool	disconnect (const QObject sender, const QString &signalMethod, const QObject receiver, const QString &slotMethod)

static bool	disconnect (const QObject sender, const QString &signalMethod, const QString &location, const QObject receiver, const QString &slotMethod)

static bool	disconnect (const QObject sender, std::nullptr_t, const QObject receiver, std::nullptr_t)

template<class Sender , class SignalClass , class... SignalArgs, class Receiver , class SlotClass , class... SlotArgs, class SlotReturn >
static bool	disconnect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver receiver, SlotReturn (SlotClass::slotMethod)(SlotArgs...))

template<class Sender , class SignalClass , class... SignalArgs, class Receiver >
static bool	disconnect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver *receiver, std::nullptr_t slotMethod=nullptr)

template<class Sender , class SignalClass , class... SignalArgs, class Receiver , class T >
static bool	disconnect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver *receiver, T slotMethod)

static QMetaObject &	staticMetaObject ()

static QString	tr (const char text, const char comment=nullptr, std::optional< int > numArg=std::optional< int >())

Related Functions inherited from QObject
T	qobject_cast (QObject *object)

	QObjectList

Detailed Description

The QItemDelegate class provides display and editing facilities for data items from a model.

QItemDelegate can be used to provide custom display features and editor widgets for item views based on QAbstractItemView subclasses. Using a delegate for this purpose allows the display and editing mechanisms to be customized and developed independently from the model and view.

The QStyledItemDelegate is used for all drawing in the item view classes. You should inherit from QStyledItemDelegate when creating a new delegate.

When displaying items from a custom model in a standard view, it is often sufficient to simply ensure that the model returns appropriate data for each of the roles which determine the appearance of items in views. The default delegate used by the CopperSpice standard views uses this role information to display items in most of the common forms expected by users. However, it is sometimes necessary to have even more control over the appearance of items than the default delegate can provide.

This class provides default implementations of the functions for painting item data in a view and editing data from item models. Default implementations of the paint() and sizeHint() virtual functions, defined in QAbstractItemDelegate, are provided to ensure that the delegate implements the correct basic behavior expected by views. You can reimplement these functions in subclasses to customize the appearance of items.

When editing data in an item view, QItemDelegate provides an editor widget, which is a widget that is placed on top of the view while editing takes place. Editors are created with a QItemEditorFactory; a default static instance provided by QItemEditorFactory is installed on all item delegates. You can set a custom factory using setItemEditorFactory() or set a new default factory with QItemEditorFactory::setDefaultFactory(). It is the data stored in the item model with the Qt::EditRole that is edited.

Only the standard editing methods for widget-based delegates are reimplemented.

createEditor(): Returns the widget used to edit data from the model
setEditorData(): Provides the widget with existing data from the model
updateEditorGeometry(): Ensures the editor is displayed correctly with respect to the view
setModelData(): Stores the updated data back into the model

The closeEditor() signal indicates the user has completed editing the data and the editor widget can be destroyed.

Standard Roles and Data Types

The default delegate used by the standard views supplied with CopperSpice associates each standard role (defined by Qt::ItemDataRole) with certain data types. Models that return data in these types can influence the appearance of the delegate as described in the following table.

Role	Accepted Types
Qt::BackgroundRole	QBrush
Qt::BackgroundColorRole	QColor (obsolete, use Qt::BackgroundRole instead)
Qt::CheckStateRole	Qt::CheckState
Qt::DecorationRole	QIcon, QPixmap and QColor
Qt::DisplayRole	QString and types with a string representation
Qt::EditRole	See QItemEditorFactory for details
Qt::FontRole	QFont
Qt::SizeHintRole	QSize
Qt::TextAlignmentRole	Qt::Alignment
Qt::ForegroundRole	QBrush
Qt::TextColorRole	QColor (obsolete, use Qt::ForegroundRole instead)

If the default delegate does not allow the level of customization that you need, either for display purposes or for editing data, it is possible to subclass QItemDelegate to implement the desired behavior.

Subclassing

When subclassing QItemDelegate to create a delegate that displays items using a custom renderer, it is important to ensure that the delegate can render items suitably for all the required states; e.g. selected, disabled, checked. The documentation for the paint() function contains some hints to show how this can be achieved.

You can provide custom editors by using a QItemEditorFactory. There is no need to subclass QItemDelegate. An alternative is to reimplement createEditor(), setEditorData(), setModelData(), and updateEditorGeometry().

QStyledItemDelegate vs. QItemDelegate

There are two delegate classes: QItemDelegate and QStyledItemDelegate. However, the default delegate is QStyledItemDelegate. These two classes are independent alternatives to painting and providing editors for items in views. The difference between them is that QStyledItemDelegate uses the current style to paint its items. We therefore recommend using QStyledItemDelegate as the base class when implementing custom delegates or when working with CopperSpice style sheets. The code required for either class should be equal unless the custom delegate needs to use the style for drawing.

See also: QStyledItemDelegate, QAbstractItemDelegate, Model/View Architecture, Delegate Classes

Constructor & Destructor Documentation

QItemDelegate::QItemDelegate ( QObject * parent = nullptr )

explicit

Constructs an item delegate with the given parent.

QItemDelegate::~QItemDelegate ( )

Destroys the item delegate.

Method Documentation

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

overridevirtual

Returns the widget used to edit the item specified by index for editing. The parent widget and style option are used to control how the editor widget appears.

See also: QAbstractItemDelegate::createEditor()

Reimplemented from QAbstractItemDelegate::createEditor()

Reimplemented in QSqlRelationalDelegate::createEditor()

void QItemDelegate::drawBackground	(	QPainter *	painter,
		const QStyleOptionViewItem &	option,
		const QModelIndex &	index
	)		const

protected

Renders the item background for the given index, using the given painter and style option.

void QItemDelegate::drawCheck	(	QPainter *	painter,
		const QStyleOptionViewItem &	option,
		const QRect &	rect,
		Qt::CheckState	state
	)		const

protectedvirtual

Renders a check indicator within the rectangle specified by rect, using the given painter and style option, using the given state.

void QItemDelegate::drawDecoration	(	QPainter *	painter,
		const QStyleOptionViewItem &	option,
		const QRect &	rect,
		const QPixmap &	pixmap
	)		const

protectedvirtual

Renders the decoration pixmap within the rectangle specified by rect using the given painter and style option.

void QItemDelegate::drawDisplay	(	QPainter *	painter,
		const QStyleOptionViewItem &	option,
		const QRect &	rect,
		const QString &	text
	)		const

protectedvirtual

Renders the item view text within the rectangle specified by rect using the given painter and style option.

void QItemDelegate::drawFocus	(	QPainter *	painter,
		const QStyleOptionViewItem &	option,
		const QRect &	rect
	)		const

protectedvirtual

Renders the region within the rectangle specified by rect, indicating that it has the focus, using the given painter and style option.

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

overrideprotectedvirtual

Reimplemented from QAbstractItemDelegate::editorEvent()

bool QItemDelegate::eventFilter	(	QObject *	object,
		QEvent *	event
	)

overrideprotectedvirtual

Returns true if the given object is a valid QWidget and the given event is handled, otherwise returns false. The following key press events are handled by default:

Tab
Backtab
Enter
Return
Esc

In the case of Tab, Backtab, Enter and Return key press events, the editor's data is committed to the model and the editor is closed. If the event is a Tab key press the view will open an editor on the next item in the view. Likewise, if the event is a Backtab key press the view will open an editor on the previous item in the view.

If the event is a Esc key press event, the editor is closed without committing its data.

See also: commitData(), closeEditor()

Reimplemented from QObject::eventFilter()

bool QItemDelegate::hasClipping ( ) const

Returns the value of the QItemDelegate::clipping property.

See also: setClipping()

QItemEditorFactory * QItemDelegate::itemEditorFactory ( ) const

Returns the editor factory used by the item delegate. If no editor factory is set, the function will return null.

See also: setItemEditorFactory()

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

overridevirtual

Renders the delegate using the given painter and style option for the item specified by index. When reimplementing this method in an inherited class make sure to update the area held by the option's rect variable, using the option's state variable to determine the state of the item to be displayed and adjust the way it is painted accordingly.

For example, a selected item may need to be displayed differently to unselected items, as shown in the following code. After painting, you should ensure that the painter is returned to the state it was supplied in when this method was called. It is a good idea to call QPainter::save() before painting and QPainter::restore() afterwards.

if (option.state & QStyle::State_Selected) {
   painter->fillRect(option.rect, option.palette.highlight());
}
 
int size = qMin(option.rect.width(), option.rect.height());
int brightness = index.model()->data(index, Qt::DisplayRole).toInt();
double radius = (size/2.0) - (brightness/255.0 * size/2.0);
 
if (radius == 0.0) {
   return;
}
 
painter->save();
painter->setRenderHint(QPainter::Antialiasing, true);
painter->setPen(Qt::NoPen);
 
if (option.state & QStyle::State_Selected) {
   painter->setBrush(option.palette.highlightedText());
} else {
   // do something
}

See also: QStyle::State

Implements QAbstractItemDelegate::paint()

void QItemDelegate::setClipping ( bool enabled )

Sets the value of the QItemDelegate::clipping property to enabled.

See also: hasClipping()

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

overridevirtual

Sets the data to be displayed and edited by the editor from the data model item specified by the model index. The default implementation stores the data in the user property for the given editor.

See also: QMetaProperty::isUser()

Reimplemented from QAbstractItemDelegate::setEditorData()

Reimplemented in QSqlRelationalDelegate::setEditorData()

void QItemDelegate::setItemEditorFactory ( QItemEditorFactory * factory )

Sets the editor factory to be used by the item delegate to be the factory specified. If no editor factory is set, the item delegate will use the default editor factory.

See also: itemEditorFactory()

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

overridevirtual

Gets data from the editor widget and stores it in the specified model at the item index. The default implementation gets the value to be stored in the data model from the editor widget's user property.

See also: QMetaProperty::isUser()

Reimplemented from QAbstractItemDelegate::setModelData()

Reimplemented in QSqlRelationalDelegate::setModelData()

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

overridevirtual

Returns the size needed by the delegate to display the item specified by index, taking into account the style information provided by option. When reimplementing this method for text items QItemDelegate adds a margin of 2 * QStyle::PM_FocusFrameHMargi) to the length of the text.

Implements QAbstractItemDelegate::sizeHint()

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

overridevirtual

Updates the editor for the item specified by index according to the style option given.

Reimplemented from QAbstractItemDelegate::updateEditorGeometry()

Property Documentation

QItemDelegate::clipping

This property holds if the delegate should clip the paint events. This property will set the paint clip to the size of the item. The default value is on. It is useful for cases such as when images are larger than the size of the item.

Properties	Class Methods
read	hasClipping
write	setClipping

Public Methods

Protected Methods

Properties

Additional Inherited Members

Detailed Description

Standard Roles and Data Types

Subclassing

QStyledItemDelegate vs. QItemDelegate

Constructor & Destructor Documentation

Method Documentation

Property Documentation