com.trolltech.qt.gui
Class QStyledItemDelegate

java.lang.Object
  extended by com.trolltech.qt.internal.QSignalEmitterInternal
      extended by com.trolltech.qt.QSignalEmitter
          extended by com.trolltech.qt.QtJambiObject
              extended by com.trolltech.qt.core.QObject
                  extended by com.trolltech.qt.gui.QAbstractItemDelegate
                      extended by com.trolltech.qt.gui.QStyledItemDelegate
All Implemented Interfaces:
QtJambiInterface

public class QStyledItemDelegate
extends QAbstractItemDelegate

The QStyledItemDelegate class provides display and editing facilities for data items from a model. When displaying data from models in Qt 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 Qt 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 Qt's model/view framework. 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 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.

Role
Accepted Types
Qt::BackgroundRole QBrush
Qt::BackgroundColorRole QColor (obsolete; use Qt::BackgroundRole instead)
Qt::CheckStateRole Qt::CheckState
Qt::DecorationRole QIcon 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)
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 EditRole that is edited. See the QItemEditorFactory class for a more high-level introduction to item editor factories. The Color Editor Factory example shows how to create custom editors with a factory.

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:

The Star Delegate example creates editors by reimplementing these methods.

QStyledItemDelegate and QItemDelegate

QStyledItemDelegate has taken over the job as default delegate - leaving
QItemDelegate behind. They will now co-exist peacefully as independent alternatives to painting and providing editors for items in views. The difference between them is that the new delegate uses the current style to paint its items. We therefore recommend using QStyledItemDelegate as base when implementing custom delegates. The code required should be equal unless the custom delegate also wishes 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, Spin Box Delegate Example, Star Delegate Example, and Color Editor Factory Example.


Nested Class Summary
 
Nested classes/interfaces inherited from class com.trolltech.qt.gui.QAbstractItemDelegate
QAbstractItemDelegate.EndEditHint
 
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
QSignalEmitter.AbstractSignal, QSignalEmitter.PrivateSignal0, QSignalEmitter.PrivateSignal1, QSignalEmitter.PrivateSignal2, QSignalEmitter.PrivateSignal3, QSignalEmitter.PrivateSignal4, QSignalEmitter.PrivateSignal5, QSignalEmitter.PrivateSignal6, QSignalEmitter.PrivateSignal7, QSignalEmitter.PrivateSignal8, QSignalEmitter.PrivateSignal9, QSignalEmitter.Signal0, QSignalEmitter.Signal1, QSignalEmitter.Signal2, QSignalEmitter.Signal3, QSignalEmitter.Signal4, QSignalEmitter.Signal5, QSignalEmitter.Signal6, QSignalEmitter.Signal7, QSignalEmitter.Signal8, QSignalEmitter.Signal9
 
Nested classes/interfaces inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
com.trolltech.qt.internal.QSignalEmitterInternal.AbstractSignalInternal
 
Field Summary
 
Fields inherited from class com.trolltech.qt.gui.QAbstractItemDelegate
closeEditor, commitData, sizeHintChanged
 
Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
currentSender
 
Constructor Summary
QStyledItemDelegate()
          Constructs an item delegate with the given parent.
QStyledItemDelegate(QObject parent)
          Constructs an item delegate with the given parent.
 
Method Summary
 java.lang.String displayText(java.lang.Object value, QLocale locale)
          This function returns the string that the delegate will use to display the Qt::DisplayRole of the model in locale.
protected  void initStyleOption(QStyleOptionViewItem option, com.trolltech.qt.core.QModelIndex index)
          Initialize option with the values using the index index.
 QItemEditorFactory itemEditorFactory()
          Returns the editor factory used by the item delegate.
 void setItemEditorFactory(QItemEditorFactory factory)
          Sets the editor factory to be used by the item delegate to be the factory specified.
 
Methods inherited from class com.trolltech.qt.gui.QAbstractItemDelegate
createEditor, editorEvent, helpEvent, paint, setEditorData, setModelData, sizeHint, updateEditorGeometry
 
Methods inherited from class com.trolltech.qt.core.QObject
childEvent, children, connectSlotsByName, customEvent, disposeLater, dumpObjectInfo, dumpObjectTree, dynamicPropertyNames, event, eventFilter, findChild, findChild, findChild, findChildren, findChildren, findChildren, findChildren, indexOfProperty, installEventFilter, isWidgetType, killTimer, moveToThread, objectName, parent, properties, property, removeEventFilter, setObjectName, setParent, setProperty, startTimer, timerEvent, toString, userProperty
 
Methods inherited from class com.trolltech.qt.QtJambiObject
dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr
 
Methods inherited from class com.trolltech.qt.QSignalEmitter
blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread
 
Methods inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
__qt_signalInitialization
 
Methods inherited from class java.lang.Object
clone, getClass, hashCode, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface com.trolltech.qt.QtJambiInterface
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership
 

Constructor Detail

QStyledItemDelegate

public QStyledItemDelegate()
Constructs an item delegate with the given parent.


QStyledItemDelegate

public QStyledItemDelegate(QObject parent)
Constructs an item delegate with the given parent.

Method Detail

itemEditorFactory

public final QItemEditorFactory itemEditorFactory()
Returns the editor factory used by the item delegate. If no editor factory is set, the function will return null.

See also:
setItemEditorFactory().


setItemEditorFactory

public final void 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().


displayText

public java.lang.String displayText(java.lang.Object value,
                                    QLocale locale)
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.


initStyleOption

protected void initStyleOption(QStyleOptionViewItem option,
                               com.trolltech.qt.core.QModelIndex index)
Initialize option with the values using the index index. This method is useful for subclasses when they need a QStyleOptionViewItem, but don't want to fill in all the information themselves. This function will check the version of the QStyleOptionViewItem and fill in the additional values for a QStyleOptionViewItemV2, QStyleOptionViewItemV3 and QStyleOptionViewItemV4.

See also:
QStyleOption::initFrom().