Qt 4.3: QItemSelectionModel Class Reference

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# QItemSelectionModel Class Reference
[QtGui module]

The QItemSelectionModel class keeps track of a view's selected items. More...

     #include <QItemSelectionModel>

Inherits QObject.

- List of all members, including inherited members

### Public Types

- enum SelectionFlag { NoUpdate, Clear, Select, Deselect, ..., ClearAndSelect }
- flags SelectionFlags

### Public Functions

- QItemSelectionModel ( QAbstractItemModel * model )
- QItemSelectionModel ( QAbstractItemModel * model, QObject * parent )
- virtual ~QItemSelectionModel ()
- bool columnIntersectsSelection ( int column, const QModelIndex & parent ) const
- QModelIndex currentIndex () const
- bool hasSelection () const
- bool isColumnSelected ( int column, const QModelIndex & parent ) const
- bool isRowSelected ( int row, const QModelIndex & parent ) const
- bool isSelected ( const QModelIndex & index ) const
- const QAbstractItemModel * model () const
- bool rowIntersectsSelection ( int row, const QModelIndex & parent ) const
- QModelIndexList selectedColumns ( int row = 0 ) const
- QModelIndexList selectedIndexes () const
- QModelIndexList selectedRows ( int column = 0 ) const
- const QItemSelection selection () const

- 29 public functions inherited from QObject

### Public Slots

- virtual void clear ()
- void clearSelection ()
- virtual void reset ()
- virtual void select ( const QModelIndex & index, QItemSelectionModel::SelectionFlags command )
- virtual void select ( const QItemSelection & selection, QItemSelectionModel::SelectionFlags command )
- void setCurrentIndex ( const QModelIndex & index, QItemSelectionModel::SelectionFlags command )

- 1 public slot inherited from QObject

### Signals

- void currentChanged ( const QModelIndex & current, const QModelIndex & previous )
- void currentColumnChanged ( const QModelIndex & current, const QModelIndex & previous )
- void currentRowChanged ( const QModelIndex & current, const QModelIndex & previous )
- void selectionChanged ( const QItemSelection & selected, const QItemSelection & deselected )

- 1 signal inherited from QObject

### Protected Functions

- void emitSelectionChanged ( const QItemSelection & newSelection, const QItemSelection & oldSelection )

- 7 protected functions inherited from QObject

### Additional Inherited Members

- 1 property inherited from QObject
- 5 static public members inherited from QObject

## Detailed Description

The QItemSelectionModel class keeps track of a view's selected items.

A QItemSelectionModel keeps track of the selected items in a view, or in several views onto the same model. It also keeps track of the currently selected item in a view.

The QItemSelectionModel class is one of the Model/View Classes and is part of Qt's model/view framework.

The selected items are stored using ranges. Whenever you want to modify the selected items use select() and provide either a QItemSelection, or a QModelIndex and a QItemSelectionModel::SelectionFlag.

The QItemSelectionModel takes a two layer approach to selection management, dealing with both selected items that have been committed and items that are part of the current selection. The current selected items are part of the current interactive selection (for example with rubber-band selection or keyboard-shift selections).

To update the currently selected items, use the bitwise OR of QItemSelectionModel::Current and any of the other SelectionFlags. If you omit the QItemSelectionModel::Current command, a new current selection will be created, and the previous one added to the committed selection. All functions operate on both layers; for example, selectedItems() will return items from both layers.

See also Model/View Programming, QAbstractItemModel, and Chart Example.

## Member Type Documentation

### enum QItemSelectionModel::SelectionFlag
flags QItemSelectionModel::SelectionFlags

This enum describes the way the selection model will be updated.

Constant | Value | Description
--- | --- | ---
`QItemSelectionModel::NoUpdate` | `0x0000` | No selection will be made.
`QItemSelectionModel::Clear` | `0x0001` | The complete selection will be cleared.
`QItemSelectionModel::Select` | `0x0002` | All specified indexes will be selected.
`QItemSelectionModel::Deselect` | `0x0004` | All specified indexes will be deselected.
`QItemSelectionModel::Toggle` | `0x0008` | All specified indexes will be selected or deselected depending on their current state.
`QItemSelectionModel::Current` | `0x0010` | The current selection will be updated.
`QItemSelectionModel::Rows` | `0x0020` | All indexes will be expanded to span rows.
`QItemSelectionModel::Columns` | `0x0040` | All indexes will be expanded to span columns.
`QItemSelectionModel::SelectCurrent` | `Select | Current` | A combination of Select and Current, provided for convenience.
`QItemSelectionModel::ToggleCurrent` | `Toggle | Current` | A combination of Toggle and Current, provided for convenience.
`QItemSelectionModel::ClearAndSelect` | `Clear | Select` | A combination of Clear and Select, provided for convenience.

The SelectionFlags type is a typedef for QFlags<SelectionFlag>. It stores an OR combination of SelectionFlag values.

## Member Function Documentation

### QItemSelectionModel::QItemSelectionModel ( QAbstractItemModel * model )

Constructs a selection model that operates on the specified item model.

### QItemSelectionModel::QItemSelectionModel ( QAbstractItemModel * model, QObject * parent )

Constructs a selection model that operates on the specified item model with parent.

### QItemSelectionModel::~QItemSelectionModel () `[virtual]`

Destroys the selection model.

### void QItemSelectionModel::clear () `[virtual slot]`

Clears the selection model. Emits selectionChanged() and currentChanged().

### void QItemSelectionModel::clearSelection () `[slot]`

Clears the selection in the selection model. Emits selectionChanged().

This function was introduced in Qt 4.2.

### bool QItemSelectionModel::columnIntersectsSelection ( int column, const QModelIndex & parent ) const

Returns true if there are any items selected in the column with the given parent.

### void QItemSelectionModel::currentChanged ( const QModelIndex & current, const QModelIndex & previous ) `[signal]`

This signal is emitted whenever the current item changes. The previous model item index is replaced by the current index as the selection's current item.

Note that this signal will not be emitted when the item model is reset.

See also currentIndex(), setCurrentIndex(), and selectionChanged().

### void QItemSelectionModel::currentColumnChanged ( const QModelIndex & current, const QModelIndex & previous ) `[signal]`

This signal is emitted if the current item changes and its column is different to the column of the previous current item.

Note that this signal will not be emitted when the item model is reset.

See also currentChanged(), currentRowChanged(), currentIndex(), and setCurrentIndex().

### QModelIndex QItemSelectionModel::currentIndex () const

Returns the model item index for the current item, or an invalid index if there is no current item.

See also setCurrentIndex().

### void QItemSelectionModel::currentRowChanged ( const QModelIndex & current, const QModelIndex & previous ) `[signal]`

This signal is emitted if the current item changes and its row is different to the row of the previous current item.

Note that this signal will not be emitted when the item model is reset.

See also currentChanged(), currentColumnChanged(), currentIndex(), and setCurrentIndex().

### void QItemSelectionModel::emitSelectionChanged ( const QItemSelection & newSelection, const QItemSelection & oldSelection ) `[protected]`

Compares the two selections newSelection and oldSelection and emits selectionChanged() with the deselected and selected items.

### bool QItemSelectionModel::hasSelection () const

Returns true if the selection model contains any selection ranges; otherwise returns false.

This function was introduced in Qt 4.2.

### bool QItemSelectionModel::isColumnSelected ( int column, const QModelIndex & parent ) const

Returns true if all items are selected in the column with the given parent.

Note that this function is usually faster than calling isSelected() on all items in the same column and that unselectable items are ignored.

### bool QItemSelectionModel::isRowSelected ( int row, const QModelIndex & parent ) const

Returns true if all items are selected in the row with the given parent.

Note that this function is usually faster than calling isSelected() on all items in the same row and that unselectable items are ignored.

### bool QItemSelectionModel::isSelected ( const QModelIndex & index ) const

Returns true if the given model item index is selected.

### const QAbstractItemModel * QItemSelectionModel::model () const

Returns the item model operated on by the selection model.

### void QItemSelectionModel::reset () `[virtual slot]`

Clears the selection model. Does not emit any signals.

### bool QItemSelectionModel::rowIntersectsSelection ( int row, const QModelIndex & parent ) const

Returns true if there are any items selected in the row with the given parent.

### void QItemSelectionModel::select ( const QModelIndex & index, QItemSelectionModel::SelectionFlags command ) `[virtual slot]`

Selects the model item index using the specified command, and emits selectionChanged().

See also QItemSelectionModel::SelectionFlags.

### void QItemSelectionModel::select ( const QItemSelection & selection, QItemSelectionModel::SelectionFlags command ) `[virtual slot]`

This is an overloaded member function, provided for convenience.

Selects the item selection using the specified command, and emits selectionChanged().

See also QItemSelectionModel::SelectionFlag.

### QModelIndexList QItemSelectionModel::selectedColumns ( int row = 0 ) const

Returns the indexes in the given row for columns where all rows are selected.

This function was introduced in Qt 4.2.

See also selectedIndexes() and selectedRows().

### QModelIndexList QItemSelectionModel::selectedIndexes () const

Returns a list of all selected model item indexes. The list contains no duplicates, and is not sorted.

### QModelIndexList QItemSelectionModel::selectedRows ( int column = 0 ) const

Returns the indexes in the given column for the rows where all columns are selected.

This function was introduced in Qt 4.2.

See also selectedIndexes() and selectedColumns().

### const QItemSelection QItemSelectionModel::selection () const

Returns the selection ranges stored in the selection model.

### void QItemSelectionModel::selectionChanged ( const QItemSelection & selected, const QItemSelection & deselected ) `[signal]`

This signal is emitted whenever the selection changes. The change in the selection is represented as an item selection of deselected items and an item selection of selected items.

Note the that the current index changes independently from the selection. Also note that this signal will not be emitted when the item model is reset.

See also select() and currentChanged().

### void QItemSelectionModel::setCurrentIndex ( const QModelIndex & index, QItemSelectionModel::SelectionFlags command ) `[slot]`

Sets the model item index to be the current item, and emits currentChanged(). The current item is used for keyboard navigation and focus indication; it is independent of any selected items, although a selected item can also be the current item.

Depending on the specified command, the index can also become part of the current selection.

See also currentIndex() and select().