CopperSpice API  1.7.2
QStyledItemDelegate Class Reference

Display and editing facilities for data items from a model. More...

Inheritance diagram for QStyledItemDelegate:
QAbstractItemDelegate QObject

Public Methods

 QStyledItemDelegate (QObject *parent=nullptr)
 
 ~QStyledItemDelegate () = default
 
QWidgetcreateEditor (QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const override
 
virtual QString displayText (const QVariant &value, const QLocale &locale) const
 
QItemEditorFactoryitemEditorFactory () const
 
void paint (QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const override
 
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< QStringdynamicPropertyNames () const
 
virtual bool event (QEvent *event)
 
template<typename 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 &objName=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 QMetaObjectmetaObject () const
 
void moveToThread (QThread *targetThread)
 
QString objectName () const
 
QObject * parent () const
 
template<class T = QVariant>
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)
 
QThreadthread () const
 

Protected Methods

bool editorEvent (QEvent *event, QAbstractItemModel *model, const QStyleOptionViewItem &option, const QModelIndex &index) override
 
bool eventFilter (QObject *object, QEvent *event) override
 
virtual void initStyleOption (QStyleOptionViewItem *option, const QModelIndex &index) const
 
- 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)
 

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)
 
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 QMetaObjectstaticMetaObject ()
 
static QString tr (const char *text, const char *comment=nullptr, std::optional< int > numArg=std::optional< int >())
 
- Properties inherited from QObject
 objectName
 

Detailed Description

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

When displaying data from models in CopperSpice item views, e.g., a QTableView, the individual items are drawn by a delegate. Also, when an item is edited, it provides an editor widget, which is placed on top of the item view while editing takes place. QStyledItemDelegate is the default delegate for all CopperSpice item views, and is installed upon them when they are created.

The QStyledItemDelegate class is one of the Model/View Classes and is part of the Model/View Programming. The delegate allows the display and editing of items to be developed independently from the model and view.

The data of items in models are assigned an Qt::ItemDataRole, each item can store a QVariant for each role. QStyledItemDelegate implements display and editing for the most common datatypes expected by users, including booleans, integers, and strings.

The data will be drawn differently depending on which role they have in the model. The following table describes the roles and the data types the delegate can handle for each of them. It is often sufficient to ensure that the model returns appropriate data for each of the roles to determine the appearance of items in views.

RoleAccepted Types
Qt::BackgroundRoleQBrush
Qt::BackgroundColorRoleQColor (obsolete, Qt::BackgroundRole instead)
Qt::CheckStateRoleQt::CheckState
Qt::DecorationRoleQIcon, QPixmap, QImage and QColor
Qt::DisplayRoleQString and types with a string representation
Qt::EditRoleSee QItemEditorFactory for details
Qt::FontRoleQFont
Qt::SizeHintRoleQSize
Qt::TextAlignmentRoleQt::Alignment
Qt::ForegroundRoleQBrush
Qt::TextColorRoleQColor (obsolete, use Qt::ForegroundRole instead)

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. See the QItemEditorFactory class for a more high-level introduction to item editor factories.

Subclassing QStyledItemDelegate

If the delegate does not support painting of the data types you need or you want to customize the drawing of items, you need to subclass QStyledItemDelegate, and reimplement paint() and possibly sizeHint(). The paint() function is called individually for each item, and with sizeHint(), you can specify the hint for each of them.

When reimplementing paint(), one would typically handle the datatypes one would like to draw and use the superclass implementation for other types.

The painting of check box indicators are performed by the current style. The style also specifies the size and the bounding rectangles in which to draw the data for the different data roles. The bounding rectangle of the item itself is also calculated by the style. When drawing already supported datatypes, it is therefore a good idea to ask the style for these bounding rectangles. The QStyle class description describes this in more detail.

If you wish to change any of the bounding rectangles calculated by the style or the painting of check box indicators, you can subclass QStyle. Note, however, that the size of the items can also be affected by reimplementing sizeHint().

It is possible for a custom delegate to provide editors without the use of an editor item factory. In this case, the following virtual functions must be reimplemented:

  • createEditor() returns the widget used to change data from the model and can be reimplemented to customize editing behavior.
  • setEditorData() provides the widget with data to manipulate.
  • updateEditorGeometry() ensures that the editor is displayed correctly with respect to the item view.
  • setModelData() returns updated data to the model.

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.

If you wish to customize the painting of item views, you should implement a custom style. Please see the QStyle class documentation for details.

See also
Delegate Classes, QItemDelegate, QAbstractItemDelegate, QStyle

Constructor & Destructor Documentation

QStyledItemDelegate::QStyledItemDelegate ( QObject parent = nullptr)
explicit

Constructs an item delegate with the given parent.

QStyledItemDelegate::~QStyledItemDelegate ( )
default

Destroys the item delegate.

Method Documentation

QWidget * QStyledItemDelegate::createEditor ( QWidget parent,
const QStyleOptionViewItem option,
const QModelIndex index 
) const
overridevirtual

Reimplemented from QAbstractItemDelegate::createEditor().

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.

QString QStyledItemDelegate::displayText ( const QVariant value,
const QLocale locale 
) const
virtual

This function returns the string that the delegate will use to display the Qt::DisplayRole of the model in locale. value is the value of the Qt::DisplayRole provided by the model.

The default implementation uses the QLocale::toString to convert value into a QString.

This function is not called for empty model indices, i.e., indices for which the model returns an invalid QVariant.

See also
QAbstractItemModel::data()
bool QStyledItemDelegate::editorEvent ( QEvent event,
QAbstractItemModel model,
const QStyleOptionViewItem option,
const QModelIndex index 
)
overrideprotectedvirtual

Reimplemented from QAbstractItemDelegate::editorEvent().

Reimplemented from QAbstractItemDelegate.

bool QStyledItemDelegate::eventFilter ( QObject object,
QEvent event 
)
overrideprotectedvirtual

Reimplemented from QObject::eventFilter().

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 object'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 object is closed without committing its data.

See also
commitData(), closeEditor()

Reimplemented from QObject.

void QStyledItemDelegate::initStyleOption ( QStyleOptionViewItem option,
const QModelIndex index 
) const
protectedvirtual

Initialize option with the values using the index index. This method is useful for subclasses when they need a QStyleOptionViewItem, but do not want to fill in all the information themselves.

See also
QStyleOption::initFrom()
QItemEditorFactory * QStyledItemDelegate::itemEditorFactory ( ) const

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

See also
setItemEditorFactory()
void QStyledItemDelegate::paint ( QPainter painter,
const QStyleOptionViewItem option,
const QModelIndex index 
) const
overridevirtual

Reimplemented from QAbstractItemDelegate::paint().

Renders the delegate using the given painter and style option for the item specified by index.

This function paints the item using the view's QStyle.

When reimplementing paint in a subclass. Use the initStyleOption() to set up the option in the same way as the QStyledItemDelegate; the option will always be an instance of QStyleOptionViewItemV4. Please see its class description for information on its contents.

Whenever possible, use the option while painting. Especially its rect variable to decide where to draw and its state to determine if it is enabled or selected.

After painting, you should ensure that the painter is returned to its the state it was supplied in when this function was called. For example, it may be useful to call QPainter::save() before painting and QPainter::restore() afterwards.

See also
QItemDelegate::paint(), QStyle::drawControl(), QStyle::CE_ItemViewItem

Implements QAbstractItemDelegate.

void QStyledItemDelegate::setEditorData ( QWidget editor,
const QModelIndex index 
) const
overridevirtual

Reimplemented from QAbstractItemDelegate::setEditorData().

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 editor widget's user property.

See also
QMetaProperty::isUser()

Reimplemented from QAbstractItemDelegate.

void QStyledItemDelegate::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 QStyledItemDelegate::setModelData ( QWidget editor,
QAbstractItemModel model,
const QModelIndex index 
) const
overridevirtual

Reimplemented from QAbstractItemDelegate::setModelData().

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.

QSize QStyledItemDelegate::sizeHint ( const QStyleOptionViewItem option,
const QModelIndex index 
) const
overridevirtual

Reimplemented from QAbstractItemDelegate::sizeHint().

Returns the size needed by the delegate to display the item specified by index, taking into account the style information provided by option.

This function uses the view's QStyle to determine the size of the item.

See also
QStyle::sizeFromContents(), QStyle::CT_ItemViewItem

Implements QAbstractItemDelegate.

void QStyledItemDelegate::updateEditorGeometry ( QWidget editor,
const QStyleOptionViewItem option,
const QModelIndex index 
) const
overridevirtual

Reimplemented from QAbstractItemDelegate::updateEditorGeometry().

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

Reimplemented from QAbstractItemDelegate.