Qt 4.8: QTreeWidget Class Reference

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# QTreeWidget Class Reference

The QTreeWidget class provides a tree view that uses a predefined tree model. More...

     #include <QTreeWidget>

Inherits: QTreeView.

- List of all members, including inherited members
- Obsolete members

## Properties

- columnCount : int
- topLevelItemCount : const int

- 11 properties inherited from QTreeView
- 16 properties inherited from QAbstractItemView
- 2 properties inherited from QAbstractScrollArea
- 6 properties inherited from QFrame
- 58 properties inherited from QWidget
- 1 property inherited from QObject

## Public Functions

| QTreeWidget ( QWidget * parent = 0 )
| ~QTreeWidget ()
void | addTopLevelItem ( QTreeWidgetItem * item )
void | addTopLevelItems ( const QList<QTreeWidgetItem *> & items )
void | closePersistentEditor ( QTreeWidgetItem * item, int column = 0 )
int | columnCount () const
int | currentColumn () const
QTreeWidgetItem * | currentItem () const
void | editItem ( QTreeWidgetItem * item, int column = 0 )
QList<QTreeWidgetItem *> | findItems ( const QString & text, Qt::MatchFlags flags, int column = 0 ) const
QTreeWidgetItem * | headerItem () const
int | indexOfTopLevelItem ( QTreeWidgetItem * item ) const
void | insertTopLevelItem ( int index, QTreeWidgetItem * item )
void | insertTopLevelItems ( int index, const QList<QTreeWidgetItem *> & items )
QTreeWidgetItem * | invisibleRootItem () const
bool | isFirstItemColumnSpanned ( const QTreeWidgetItem * item ) const
QTreeWidgetItem * | itemAbove ( const QTreeWidgetItem * item ) const
QTreeWidgetItem * | itemAt ( const QPoint & p ) const
QTreeWidgetItem * | itemAt ( int x, int y ) const
QTreeWidgetItem * | itemBelow ( const QTreeWidgetItem * item ) const
QWidget * | itemWidget ( QTreeWidgetItem * item, int column ) const
void | openPersistentEditor ( QTreeWidgetItem * item, int column = 0 )
void | removeItemWidget ( QTreeWidgetItem * item, int column )
QList<QTreeWidgetItem *> | selectedItems () const
void | setColumnCount ( int columns )
void | setCurrentItem ( QTreeWidgetItem * item )
void | setCurrentItem ( QTreeWidgetItem * item, int column )
void | setCurrentItem ( QTreeWidgetItem * item, int column, QItemSelectionModel::SelectionFlags command )
void | setFirstItemColumnSpanned ( const QTreeWidgetItem * item, bool span )
void | setHeaderItem ( QTreeWidgetItem * item )
void | setHeaderLabel ( const QString & label )
void | setHeaderLabels ( const QStringList & labels )
void | setItemWidget ( QTreeWidgetItem * item, int column, QWidget * widget )
int | sortColumn () const
void | sortItems ( int column, Qt::SortOrder order )
QTreeWidgetItem * | takeTopLevelItem ( int index )
QTreeWidgetItem * | topLevelItem ( int index ) const
int | topLevelItemCount () const
QRect | visualItemRect ( const QTreeWidgetItem * item ) const

## Reimplemented Public Functions

virtual void | setSelectionModel ( QItemSelectionModel * selectionModel )

- 49 public functions inherited from QTreeView
- 57 public functions inherited from QAbstractItemView
- 17 public functions inherited from QAbstractScrollArea
- 14 public functions inherited from QFrame
- 221 public functions inherited from QWidget
- 29 public functions inherited from QObject
- 13 public functions inherited from QPaintDevice

## Public Slots

void | clear ()
void | collapseItem ( const QTreeWidgetItem * item )
void | expandItem ( const QTreeWidgetItem * item )
void | scrollToItem ( const QTreeWidgetItem * item, QAbstractItemView::ScrollHint hint = EnsureVisible )

- 8 public slots inherited from QTreeView
- 9 public slots inherited from QAbstractItemView
- 19 public slots inherited from QWidget
- 1 public slot inherited from QObject

## Signals

void | currentItemChanged ( QTreeWidgetItem * current, QTreeWidgetItem * previous )
void | itemActivated ( QTreeWidgetItem * item, int column )
void | itemChanged ( QTreeWidgetItem * item, int column )
void | itemClicked ( QTreeWidgetItem * item, int column )
void | itemCollapsed ( QTreeWidgetItem * item )
void | itemDoubleClicked ( QTreeWidgetItem * item, int column )
void | itemEntered ( QTreeWidgetItem * item, int column )
void | itemExpanded ( QTreeWidgetItem * item )
void | itemPressed ( QTreeWidgetItem * item, int column )
void | itemSelectionChanged ()

- 2 signals inherited from QTreeView
- 6 signals inherited from QAbstractItemView
- 1 signal inherited from QWidget
- 1 signal inherited from QObject

## Protected Functions

virtual bool | dropMimeData ( QTreeWidgetItem * parent, int index, const QMimeData * data, Qt::DropAction action )
QModelIndex | indexFromItem ( QTreeWidgetItem * item, int column = 0 ) const
QTreeWidgetItem * | itemFromIndex ( const QModelIndex & index ) const
virtual QMimeData * | mimeData ( const QList<QTreeWidgetItem *> items ) const
virtual QStringList | mimeTypes () const
virtual Qt::DropActions | supportedDropActions () const

## Reimplemented Protected Functions

virtual void | dropEvent ( QDropEvent * event )
virtual bool | event ( QEvent * e )

- 28 protected functions inherited from QTreeView
- 36 protected functions inherited from QAbstractItemView
- 18 protected functions inherited from QAbstractScrollArea
- 3 protected functions inherited from QFrame
- 37 protected functions inherited from QWidget
- 8 protected functions inherited from QObject
- 1 protected function inherited from QPaintDevice

### Additional Inherited Members

- 4 static public members inherited from QWidget
- 7 static public members inherited from QObject
- 4 protected slots inherited from QTreeView
- 9 protected slots inherited from QAbstractItemView
- 1 protected slot inherited from QAbstractScrollArea
- 1 protected slot inherited from QWidget

## Detailed Description

The QTreeWidget class provides a tree view that uses a predefined tree model.

The QTreeWidget class is a convenience class that provides a standard tree widget with a classic item-based interface similar to that used by the QListView class in Qt 3. This class is based on Qt's Model/View architecture and uses a default model to hold items, each of which is a QTreeWidgetItem.

Developers who do not need the flexibility of the Model/View framework can use this class to create simple hierarchical lists very easily. A more flexible approach involves combining a QTreeView with a standard item model. This allows the storage of data to be separated from its representation.

In its simplest form, a tree widget can be constructed in the following way:

     QTreeWidget *treeWidget = new QTreeWidget();
     treeWidget->setColumnCount(1);
     QList<QTreeWidgetItem *> items;
     for (int i = 0; i < 10; ++i)
         items.append(new QTreeWidgetItem((QTreeWidget*)0, QStringList(QString("item: %1").arg(i))));
     treeWidget->insertTopLevelItems(0, items);

Before items can be added to the tree widget, the number of columns must be set with setColumnCount(). This allows each item to have one or more labels or other decorations. The number of columns in use can be found with the columnCount() function.

The tree can have a header that contains a section for each column in the widget. It is easiest to set up the labels for each section by supplying a list of strings with setHeaderLabels(), but a custom header can be constructed with a QTreeWidgetItem and inserted into the tree with the setHeaderItem() function.

The items in the tree can be sorted by column according to a predefined sort order. If sorting is enabled, the user can sort the items by clicking on a column header. Sorting can be enabled or disabled by calling setSortingEnabled(). The isSortingEnabled() function indicates whether sorting is enabled.

A Windows XP style tree widget. | A Macintosh style tree widget. | A Plastique style tree widget.

See also QTreeWidgetItem, QTreeWidgetItemIterator, QTreeView, Model/View Programming, and Settings Editor Example.

## Property Documentation

### columnCount : int

This property holds the number of columns displayed in the tree widget.

By default, this property has a value of 1.

Access functions:

int | columnCount () const
void | setColumnCount ( int columns )

### topLevelItemCount : const int

This property holds the number of top-level items.

By default, this property has a value of 0.

Access functions:

int | topLevelItemCount () const

See also columnCount() and currentItem().

## Member Function Documentation

### QTreeWidget::QTreeWidget ( QWidget * parent = 0 )

Constructs a tree widget with the given parent.

### QTreeWidget::~QTreeWidget ()

Destroys the tree widget and all its items.

### void QTreeWidget::addTopLevelItem ( QTreeWidgetItem * item )

Appends the item as a top-level item in the widget.

This function was introduced in Qt 4.1.

See also insertTopLevelItem().

### void QTreeWidget::addTopLevelItems ( const QList<QTreeWidgetItem *> & items )

Appends the list of items as a top-level items in the widget.

See also insertTopLevelItems().

### void QTreeWidget::clear ()`[slot]`

Clears the tree widget by removing all of its items and selections.

Note: Since each item is removed from the tree widget before being deleted, the return value of QTreeWidgetItem::treeWidget() will be invalid when called from an item's destructor.

See also takeTopLevelItem(), topLevelItemCount(), and columnCount().

### void QTreeWidget::closePersistentEditor ( QTreeWidgetItem * item, int column = 0 )

Closes the persistent editor for the item in the given column.

This function has no effect if no persistent editor is open for this combination of item and column.

See also openPersistentEditor().

### void QTreeWidget::collapseItem ( const QTreeWidgetItem * item )`[slot]`

Closes the item. This causes the tree containing the item's children to be collapsed.

See also expandItem(), currentItem(), itemAt(), and topLevelItem().

### int QTreeWidget::currentColumn () const

Returns the current column in the tree widget.

This function was introduced in Qt 4.1.

See also setCurrentItem() and columnCount().

### QTreeWidgetItem * QTreeWidget::currentItem () const

Returns the current item in the tree widget.

See also setCurrentItem() and currentItemChanged().

### void QTreeWidget::currentItemChanged ( QTreeWidgetItem * current, QTreeWidgetItem * previous )`[signal]`

This signal is emitted when the current item changes. The current item is specified by current, and this replaces the previous current item.

See also setCurrentItem().

### void QTreeWidget::dropEvent ( QDropEvent * event )`[virtual protected]`

Reimplemented from QWidget::dropEvent().

### bool QTreeWidget::dropMimeData ( QTreeWidgetItem * parent, int index, const QMimeData * data, Qt::DropAction action )`[virtual protected]`

Handles the data supplied by a drag and drop operation that ended with the given action in the index in the given parent item.

The default implementation returns true if the drop was successfully handled by decoding the mime data and inserting it into the model; otherwise it returns false.

See also supportedDropActions().

### void QTreeWidget::editItem ( QTreeWidgetItem * item, int column = 0 )

Starts editing the item in the given column if it is editable.

### bool QTreeWidget::event ( QEvent * e )`[virtual protected]`

Reimplemented from QObject::event().

### void QTreeWidget::expandItem ( const QTreeWidgetItem * item )`[slot]`

Expands the item. This causes the tree containing the item's children to be expanded.

See also collapseItem(), currentItem(), itemAt(), topLevelItem(), and itemExpanded().

### QList<QTreeWidgetItem *> QTreeWidget::findItems ( const QString & text, Qt::MatchFlags flags, int column = 0 ) const

Returns a list of items that match the given text, using the given flags, in the given column.

### QTreeWidgetItem * QTreeWidget::headerItem () const

Returns the item used for the tree widget's header.

See also setHeaderItem().

### QModelIndex QTreeWidget::indexFromItem ( QTreeWidgetItem * item, int column = 0 ) const`[protected]`

Returns the QModelIndex assocated with the given item in the given column.

See also itemFromIndex() and topLevelItem().

### int QTreeWidget::indexOfTopLevelItem ( QTreeWidgetItem * item ) const

Returns the index of the given top-level item, or -1 if the item cannot be found.

See also sortItems() and topLevelItemCount().

### void QTreeWidget::insertTopLevelItem ( int index, QTreeWidgetItem * item )

Inserts the item at index in the top level in the view.

If the item has already been inserted somewhere else it wont be inserted.

See also addTopLevelItem() and columnCount().

### void QTreeWidget::insertTopLevelItems ( int index, const QList<QTreeWidgetItem *> & items )

Inserts the list of items at index in the top level in the view.

Items that have already been inserted somewhere else wont be inserted.

This function was introduced in Qt 4.1.

See also addTopLevelItems().

### QTreeWidgetItem * QTreeWidget::invisibleRootItem () const

Returns the tree widget's invisible root item.

The invisible root item provides access to the tree widget's top-level items through the QTreeWidgetItem API, making it possible to write functions that can treat top-level items and their children in a uniform way; for example, recursive functions.

This function was introduced in Qt 4.2.

### bool QTreeWidget::isFirstItemColumnSpanned ( const QTreeWidgetItem * item ) const

Returns true if the given item is set to show only one section over all columns; otherwise returns false.

This function was introduced in Qt 4.3.

See also setFirstItemColumnSpanned().

### QTreeWidgetItem * QTreeWidget::itemAbove ( const QTreeWidgetItem * item ) const

Returns the item above the given item.

This function was introduced in Qt 4.3.

### void QTreeWidget::itemActivated ( QTreeWidgetItem * item, int column )`[signal]`

This signal is emitted when the user activates an item by single- or double-clicking (depending on the platform, i.e. on the QStyle::SH_ItemView_ActivateItemOnSingleClick style hint) or pressing a special key (e.g., Enter).

The specified item is the item that was clicked, or 0 if no item was clicked. The column is the item's column that was clicked, or -1 if no item was clicked.

### QTreeWidgetItem * QTreeWidget::itemAt ( const QPoint & p ) const

Returns a pointer to the item at the coordinates p. The coordinates are relative to the tree widget's viewport().

See also visualItemRect().

### QTreeWidgetItem * QTreeWidget::itemAt ( int x, int y ) const

This is an overloaded function.

Returns a pointer to the item at the coordinates (x, y). The coordinates are relative to the tree widget's viewport().

### QTreeWidgetItem * QTreeWidget::itemBelow ( const QTreeWidgetItem * item ) const

Returns the item visually below the given item.

This function was introduced in Qt 4.3.

### void QTreeWidget::itemChanged ( QTreeWidgetItem * item, int column )`[signal]`

This signal is emitted when the contents of the column in the specified item changes.

### void QTreeWidget::itemClicked ( QTreeWidgetItem * item, int column )`[signal]`

This signal is emitted when the user clicks inside the widget.

The specified item is the item that was clicked. The column is the item's column that was clicked. If no item was clicked, no signal will be emitted.

### void QTreeWidget::itemCollapsed ( QTreeWidgetItem * item )`[signal]`

This signal is emitted when the specified item is collapsed so that none of its children are displayed.

Note: This signal will not be emitted if an item changes its state when collapseAll() is invoked.

See also QTreeWidgetItem::isExpanded(), itemExpanded(), and collapseItem().

### void QTreeWidget::itemDoubleClicked ( QTreeWidgetItem * item, int column )`[signal]`

This signal is emitted when the user double clicks inside the widget.

The specified item is the item that was clicked, or 0 if no item was clicked. The column is the item's column that was clicked. If no item was double clicked, no signal will be emitted.

### void QTreeWidget::itemEntered ( QTreeWidgetItem * item, int column )`[signal]`

This signal is emitted when the mouse cursor enters an item over the specified column. QTreeWidget mouse tracking needs to be enabled for this feature to work.

### void QTreeWidget::itemExpanded ( QTreeWidgetItem * item )`[signal]`

This signal is emitted when the specified item is expanded so that all of its children are displayed.

Note: This signal will not be emitted if an item changes its state when expandAll() is invoked.

See also setItemExpanded(), QTreeWidgetItem::isExpanded(), itemCollapsed(), and expandItem().

### QTreeWidgetItem * QTreeWidget::itemFromIndex ( const QModelIndex & index ) const`[protected]`

Returns a pointer to the QTreeWidgetItem assocated with the given index.

See also indexFromItem().

### void QTreeWidget::itemPressed ( QTreeWidgetItem * item, int column )`[signal]`

This signal is emitted when the user presses a mouse button inside the widget.

The specified item is the item that was clicked, or 0 if no item was clicked. The column is the item's column that was clicked, or -1 if no item was clicked.

### void QTreeWidget::itemSelectionChanged ()`[signal]`

This signal is emitted when the selection changes in the tree widget. The current selection can be found with selectedItems().

### QWidget * QTreeWidget::itemWidget ( QTreeWidgetItem * item, int column ) const

Returns the widget displayed in the cell specified by item and the given column.

Note: The tree takes ownership of the widget.

This function was introduced in Qt 4.1.

See also setItemWidget().

### QMimeData * QTreeWidget::mimeData ( const QList<QTreeWidgetItem *> items ) const`[virtual protected]`

Returns an object that contains a serialized description of the specified items. The format used to describe the items is obtained from the mimeTypes() function.

If the list of items is empty, 0 is returned rather than a serialized empty list.

### QStringList QTreeWidget::mimeTypes () const`[virtual protected]`

Returns a list of MIME types that can be used to describe a list of treewidget items.

See also mimeData().

### void QTreeWidget::openPersistentEditor ( QTreeWidgetItem * item, int column = 0 )

Opens a persistent editor for the item in the given column.

See also closePersistentEditor().

### void QTreeWidget::removeItemWidget ( QTreeWidgetItem * item, int column )

Removes the widget set in the given item in the given column.

This function was introduced in Qt 4.3.

### void QTreeWidget::scrollToItem ( const QTreeWidgetItem * item, QAbstractItemView::ScrollHint hint = EnsureVisible )`[slot]`

Ensures that the item is visible, scrolling the view if necessary using the specified hint.

See also currentItem(), itemAt(), and topLevelItem().

### QList<QTreeWidgetItem *> QTreeWidget::selectedItems () const

Returns a list of all selected non-hidden items.

See also itemSelectionChanged().

### void QTreeWidget::setCurrentItem ( QTreeWidgetItem * item )

Sets the current item in the tree widget.

Unless the selection mode is NoSelection, the item is also be selected.

See also currentItem() and currentItemChanged().

### void QTreeWidget::setCurrentItem ( QTreeWidgetItem * item, int column )

Sets the current item in the tree widget and the current column to column.

This function was introduced in Qt 4.1.

See also currentItem().

### void QTreeWidget::setCurrentItem ( QTreeWidgetItem * item, int column, QItemSelectionModel::SelectionFlags command )

Sets the current item in the tree widget and the current column to column, using the given command.

This function was introduced in Qt 4.4.

See also currentItem().

### void QTreeWidget::setFirstItemColumnSpanned ( const QTreeWidgetItem * item, bool span )

Sets the given item to only show one section for all columns if span is true; otherwise the item will show one section per column.

This function was introduced in Qt 4.3.

See also isFirstItemColumnSpanned().

### void QTreeWidget::setHeaderItem ( QTreeWidgetItem * item )

Sets the header item for the tree widget. The label for each column in the header is supplied by the corresponding label in the item.

The tree widget takes ownership of the item.

See also headerItem() and setHeaderLabels().

### void QTreeWidget::setHeaderLabel ( const QString & label )

Same as setHeaderLabels(QStringList(label)).

This function was introduced in Qt 4.2.

### void QTreeWidget::setHeaderLabels ( const QStringList & labels )

Adds a column in the header for each item in the labels list, and sets the label for each column.

Note that setHeaderLabels() won't remove existing columns.

See also setHeaderItem() and setHeaderLabel().

### void QTreeWidget::setItemWidget ( QTreeWidgetItem * item, int column, QWidget * widget )

Sets the given widget to be displayed in the cell specified by the given item and column.

The given widget's autoFillBackground property must be set to true, otherwise the widget's background will be transparent, showing both the model data and the tree widget item.

This function should only be used to display static content in the place of a tree widget item. If you want to display custom dynamic content or implement a custom editor widget, use QTreeView and subclass QItemDelegate instead.

This function cannot be called before the item hierarchy has been set up, i.e., the QTreeWidgetItem that will hold widget must have been added to the view before widget is set.

Note: The tree takes ownership of the widget.

This function was introduced in Qt 4.1.

See also itemWidget() and Delegate Classes.

### void QTreeWidget::setSelectionModel ( QItemSelectionModel * selectionModel )`[virtual]`

Reimplemented from QAbstractItemView::setSelectionModel().

### int QTreeWidget::sortColumn () const

Returns the column used to sort the contents of the widget.

This function was introduced in Qt 4.1.

See also sortItems().

### void QTreeWidget::sortItems ( int column, Qt::SortOrder order )

Sorts the items in the widget in the specified order by the values in the given column.

See also sortColumn().

### Qt::DropActions QTreeWidget::supportedDropActions () const`[virtual protected]`

Returns the drop actions supported by this view.

See also Qt::DropActions.

### QTreeWidgetItem * QTreeWidget::takeTopLevelItem ( int index )

Removes the top-level item at the given index in the tree and returns it, otherwise returns 0;

See also insertTopLevelItem(), topLevelItem(), and topLevelItemCount().

### QTreeWidgetItem * QTreeWidget::topLevelItem ( int index ) const

Returns the top level item at the given index, or 0 if the item does not exist.

See also topLevelItemCount() and insertTopLevelItem().

### QRect QTreeWidget::visualItemRect ( const QTreeWidgetItem * item ) const

Returns the rectangle on the viewport occupied by the item at item.

See also itemAt().