Qt 4.0: QComboBox Class Reference

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# QComboBox Class Reference
[QtGui module]

The QComboBox widget is a combined button and popup list. More...

    #include <QComboBox>

Inherits QWidget.

- List of all members, including inherited members
- Qt 3 support members

### Public Types

- enum InsertPolicy { NoInsert, InsertAtTop, InsertAtCurrent, InsertAtBottom, InsertAfterCurrent, InsertBeforeCurrent }
- enum SizeAdjustPolicy { AdjustToContents, AdjustToContentsOnFirstShow, AdjustToMinimumContentsLength }

### Properties

autoCompletion : bool count : const int currentIndex : int currentText : const QString duplicatesEnabled : bool editable : bool frame : bool | iconSize : QSize insertPolicy : InsertPolicy maxCount : int maxVisibleItems : int minimumContentsLength : int modelColumn : bool sizeAdjustPolicy : SizeAdjustPolicy

- 52 properties inherited from QWidget
- 1 property inherited from QObject

### Public Functions

- QComboBox ( QWidget * parent = 0 )
- ~QComboBox ()
- void addItem ( const QString & text, const QVariant & userData = QVariant() )
- void addItem ( const QIcon & icon, const QString & text, const QVariant & userData = QVariant() )
- void addItems ( const QStringList & texts )
- bool autoCompletion () const
- int count () const
- int currentIndex () const
- QString currentText () const
- bool duplicatesEnabled () const
- int findData ( const QVariant & data, int role = Qt::UserRole, Qt::MatchFlags flags = Qt::MatchExactly | Qt::MatchCaseSensitive ) const
- int findText ( const QString & text, Qt::MatchFlags flags = Qt::MatchExactly | Qt::MatchCaseSensitive ) const
- bool hasFrame () const
- virtual void hidePopup ()
- QSize iconSize () const
- void insertItem ( int index, const QString & text, const QVariant & userData = QVariant() )
- void insertItem ( int index, const QIcon & icon, const QString & text, const QVariant & userData = QVariant() )
- void insertItems ( int index, const QStringList & list )
- InsertPolicy insertPolicy () const
- bool isEditable () const
- QVariant itemData ( int index, int role = Qt::UserRole ) const
- QAbstractItemDelegate * itemDelegate () const
- QIcon itemIcon ( int index ) const
- QString itemText ( int index ) const
- QLineEdit * lineEdit () const
- int maxCount () const
- int maxVisibleItems () const
- int minimumContentsLength () const
- QAbstractItemModel * model () const
- int modelColumn () const
- void removeItem ( int index )
- QModelIndex rootModelIndex () const
- void setAutoCompletion ( bool enable )
- void setCurrentIndex ( int index )
- void setDuplicatesEnabled ( bool enable )
- void setEditable ( bool editable )
- void setFrame ( bool )
- void setIconSize ( const QSize & size )
- void setInsertPolicy ( InsertPolicy policy )
- void setItemData ( int index, const QVariant & value, int role = Qt::UserRole )
- void setItemDelegate ( QAbstractItemDelegate * delegate )
- void setItemIcon ( int index, const QIcon & icon )
- void setItemText ( int index, const QString & text )
- void setLineEdit ( QLineEdit * edit )
- void setMaxCount ( int max )
- void setMaxVisibleItems ( int maxItems )
- void setMinimumContentsLength ( int characters )
- void setModel ( QAbstractItemModel * model )
- void setModelColumn ( int visibleColumn )
- void setRootModelIndex ( const QModelIndex & index )
- void setSizeAdjustPolicy ( SizeAdjustPolicy policy )
- void setValidator ( const QValidator * validator )
- void setView ( QAbstractItemView * itemView )
- virtual void showPopup ()
- SizeAdjustPolicy sizeAdjustPolicy () const
- const QValidator * validator () const
- QAbstractItemView * view () const

- 184 public functions inherited from QWidget
- 28 public functions inherited from QObject
- 10 public functions inherited from QPaintDevice

### Public Slots

- void clear ()
- void clearEditText ()
- void setEditText ( const QString & text )

- 17 public slots inherited from QWidget
- 1 public slot inherited from QObject

### Signals

- void activated ( int index )
- void activated ( const QString & text )
- void editTextChanged ( const QString & text )
- void highlighted ( int index )
- void highlighted ( const QString & text )

- 1 signal inherited from QWidget
- 1 signal inherited from QObject

### Additional Inherited Members

- 4 static public members inherited from QWidget
- 4 static public members inherited from QObject
- 39 protected functions inherited from QWidget
- 7 protected functions inherited from QObject

## Detailed Description

The QComboBox widget is a combined button and popup list.

A QComboBox provides a means of presenting a list of options to the user in a way that takes up the minimum amount of screen space.

A combobox is a selection widget that displays the current item, and can pop up a list of selectable items. A combobox may be editable, allowing the user to modify each item in the list.

Comboboxes can contain pixmaps as well as strings; the insertItem() and changeItem() functions are suitably overloaded. For editable comboboxes, the function clearEdit() is provided, to clear the displayed string without changing the combobox's contents.

A combobox emits two signals, activated() and highlighted(), when a new item has been activated (selected) or highlighted (made current). Both signals exist in two versions, one with a QString argument and one with an `int` argument. If the user highlights or activates a pixmap, only the `int` signals are emitted. Whenever the text of an editable combobox is changed the editTextChanged() signal is emitted.

When the user enters a new string in an editable combobox, the widget may or may not insert it, and it can insert it in several locations. The default policy is is AtBottom but you can change this using setInsertPolicy().

It is possible to constrain the input to an editable combobox using QValidator; see setValidator(). By default, any input is accepted.

A combobox can be populated using the insert functions, insertStringList() and insertItem() for example. Items can be changed with changeItem(). An item can be removed with removeItem() and all items can be removed with clear(). The text of the current item is returned by currentText(), and the text of a numbered item is returned with text(). The current item can be set with setCurrentIndex(). The number of items in the combobox is returned by count(); the maximum number of items can be set with setMaxCount(). You can allow editing using setEditable(). For editable comboboxes you can set auto-completion using setAutoCompletion() and whether or not the user can add duplicates is set with setDuplicatesEnabled().

See also QLineEdit, QSpinBox, QRadioButton, QButtonGroup, and GUI Design Handbook: Combo Box, Drop-Down List Box.

## Member Type Documentation

### enum QComboBox::InsertPolicy

This enum specifies what the QComboBox should do when a new string is entered by the user.

Constant | Value | Description
--- | --- | ---
`QComboBox::NoInsert` | `0` | The string will not be inserted into the combobox.
`QComboBox::InsertAtTop` | `1` | The string will be inserted as the first item in the combobox.
`QComboBox::InsertAtCurrent` | `2` | The current item will be replaced by the string.
`QComboBox::InsertAtBottom` | `3` | The string will be inserted after the last item in the combobox.
`QComboBox::InsertAfterCurrent` | `4` | The string is inserted after the current item in the combobox.
`QComboBox::InsertBeforeCurrent` | `5` | The string is inserted before the current item in the combobox.

### enum QComboBox::SizeAdjustPolicy

This enum specifies how the size of the QComboBox should adjust when new content is added or content changes.

Constant | Value | Description
--- | --- | ---
`QComboBox::AdjustToContents` | `0` | The combobox will always adjust to the contens
`QComboBox::AdjustToContentsOnFirstShow` | `1` | The combobox will adjust to its contents the first time it is show.
`QComboBox::AdjustToMinimumContentsLength` | `2` | The combobox only adjusts to the minimumContentsLength

## Property Documentation

### autoCompletion : bool

This property holds whether the combobox provides auto-completion for editable items.

Access functions:

- bool autoCompletion () const
- void setAutoCompletion ( bool enable )

See also editable.

### count : const int

This property holds the number of items in the combobox.

Access functions:

- int count () const

### currentIndex : int

This property holds the index of the current item in the combobox. The index can change when inserting or removing items.

Access functions:

- int currentIndex () const
- void setCurrentIndex ( int index )

### currentText : const QString

This property holds the text of the current item.

Access functions:

- QString currentText () const

### duplicatesEnabled : bool

This property holds whether the user can enter duplicate items into the combobox.

Note that it is always possible to programatically insert duplicate items into the combobox.

Access functions:

- bool duplicatesEnabled () const
- void setDuplicatesEnabled ( bool enable )

### editable : bool

This property holds whether the combobox can be edited by the user.

Access functions:

- bool isEditable () const
- void setEditable ( bool editable )

### frame : bool

This property holds whether the combo box draws itself with a frame.

If enabled (the default) the combo box draws itself inside a frame, otherwise the combo box draws itself without any frame.

Access functions:

- bool hasFrame () const
- void setFrame ( bool )

### iconSize : QSize

This property holds the size of the icons shown in the combobox.

Unless explicitly set this returns the default value of the current style.

Access functions:

- QSize iconSize () const
- void setIconSize ( const QSize & size )

### insertPolicy : InsertPolicy

This property holds the policy used to determine where user-inserted items should appear in the combobox.

The default value is AtBottom, indicating that new items will appear at the bottom of the list of items.

Access functions:

- InsertPolicy insertPolicy () const
- void setInsertPolicy ( InsertPolicy policy )

See also InsertPolicy.

### maxCount : int

This property holds the maximum number of items allowed in the combobox.

Note: If you set the maximum number to be less then the current amount of items in the combobox, the extra items will be truncated. This also applies if you have set an external model on the combobox.

Access functions:

- int maxCount () const
- void setMaxCount ( int max )

### maxVisibleItems : int

This property holds the maximum allowed size on screen of the combobox.

Access functions:

- int maxVisibleItems () const
- void setMaxVisibleItems ( int maxItems )

### minimumContentsLength : int

This property holds the value describing the minimum number of characters that will fit into the combobox.

This value is ignored if AdjustToMinimumContentsLength is not set. The default value is 0.

Access functions:

- int minimumContentsLength () const
- void setMinimumContentsLength ( int characters )

See also sizeAdjustPolicy.

### modelColumn : bool

This property holds the column in the model that is visible.

Access functions:

- int modelColumn () const
- void setModelColumn ( int visibleColumn )

### sizeAdjustPolicy : SizeAdjustPolicy

This property holds the policy describing how the size of the combobox changes when the content changes.

The default value is AdjustToContentsOnFirstShow.

Access functions:

- SizeAdjustPolicy sizeAdjustPolicy () const
- void setSizeAdjustPolicy ( SizeAdjustPolicy policy )

See also SizeAdjustPolicy.

## Member Function Documentation

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

Constructs a combobox with the given parent, using the default model QStandardItemModel.

### QComboBox::~QComboBox ()

Destroys the combobox.

### void QComboBox::activated ( int index ) `[signal]`

This signal is sent when an item in the combobox is activated. The item's index is given.

### void QComboBox::activated ( const QString & text ) `[signal]`

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

This signal is sent when an item in the combobox is activated. The item's text is given.

### void QComboBox::addItem ( const QString & text, const QVariant & userData = QVariant() )

Adds an item to the combobox with the given text, and containing the specified userData. The item is appended to the list of existing items.

### void QComboBox::addItem ( const QIcon & icon, const QString & text, const QVariant & userData = QVariant() )

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Adds an item to the combobox with the given icon and text, and containing the specified userData. The item is appended to the list of existing items.

### void QComboBox::addItems ( const QStringList & texts )

Adds each of the strings in the given texts to the combobox. Each item is appended to the list of existing items in turn.

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

Clears the combobox, removing all items.

Note: If you have set an external model on the combobox this model will still be cleared when calling this function.

### void QComboBox::clearEditText () `[slot]`

Clears the contents of the line edit used for editing in the combobox.

### void QComboBox::editTextChanged ( const QString & text ) `[signal]`

This signal is emitted when the text in the combobox's line edit widget is changed. The new text is specified by text.

### int QComboBox::findData ( const QVariant & data, int role = Qt::UserRole, Qt::MatchFlags flags = Qt::MatchExactly | Qt::MatchCaseSensitive ) const

Returns the index of the item containing the given data for the given role; otherwise returns -1.

The flags specify how the items in the combobox are searched.

### int QComboBox::findText ( const QString & text, Qt::MatchFlags flags = Qt::MatchExactly | Qt::MatchCaseSensitive ) const

Returns the index of the item containing the given text; otherwise returns -1.

The flags specify how the items in the combobox are searched.

### void QComboBox::hidePopup () `[virtual]`

Hides the list of items in the combobox if it is currently visible; otherwise this function does nothing.

### void QComboBox::highlighted ( int index ) `[signal]`

This signal is sent when an item in the combobox is highlighted. The item's index is given.

### void QComboBox::highlighted ( const QString & text ) `[signal]`

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

This signal is sent when an item in the combobox is highlighted. The item's text is given.

### void QComboBox::insertItem ( int index, const QString & text, const QVariant & userData = QVariant() )

Inserts the text and userData into the combobox at the given index.

### void QComboBox::insertItem ( int index, const QIcon & icon, const QString & text, const QVariant & userData = QVariant() )

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Inserts the icon, text and userData into the combobox at the given index.

### void QComboBox::insertItems ( int index, const QStringList & list )

Inserts the strings from the list into the combobox as separate items, starting at the index specified.

### QVariant QComboBox::itemData ( int index, int role = Qt::UserRole ) const

Returns the data for the given role in the given index in the combobox, or QVariant::Invalid if there is no data for this role.

See also setItemData().

### QAbstractItemDelegate * QComboBox::itemDelegate () const

Returns the item delegate used by the popup list view.

See also setItemDelegate().

### QIcon QComboBox::itemIcon ( int index ) const

Returns the icon for the given index in the combobox.

See also setItemIcon().

### QString QComboBox::itemText ( int index ) const

Returns the text for the given index in the combobox.

See also setItemText().

### QLineEdit * QComboBox::lineEdit () const

Returns the line edit used to edit items in the combobox, or 0 if there is no line edit.

Only editable combo boxes have a line edit.

See also setLineEdit().

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

Returns the model used by the combobox.

See also setModel().

### void QComboBox::removeItem ( int index )

Removes the item at the given index from the combobox. This will update the current index if the index is removed.

### QModelIndex QComboBox::rootModelIndex () const

Returns the root model item index for the items in the combobox.

See also setRootModelIndex().

### void QComboBox::setEditText ( const QString & text ) `[slot]`

Sets the text in the combobox's text edit.

### void QComboBox::setItemData ( int index, const QVariant & value, int role = Qt::UserRole )

Sets the data role for the item on the given index in the combobox to the specified value.

See also itemData().

### void QComboBox::setItemDelegate ( QAbstractItemDelegate * delegate )

Sets the item delegate for the popup list view. The combobox takes ownership of the delegate.

See also itemDelegate().

### void QComboBox::setItemIcon ( int index, const QIcon & icon )

Sets the icon for the item on the given index in the combobox.

See also itemIcon().

### void QComboBox::setItemText ( int index, const QString & text )

Sets the text for the item on the given index in the combobox.

See also itemText().

### void QComboBox::setLineEdit ( QLineEdit * edit )

Sets the line edit to use instead of the current line edit widget.

See also lineEdit().

### void QComboBox::setModel ( QAbstractItemModel * model )

Sets the model to be model. model must not be 0. If you want to clear the contents of a model, call clear().

See also model() and clear().

### void QComboBox::setRootModelIndex ( const QModelIndex & index )

Sets the root model item index for the items in the combobox.

See also rootModelIndex().

### void QComboBox::setValidator ( const QValidator * validator )

Sets the validator to use instead of the current validator.

See also validator().

### void QComboBox::setView ( QAbstractItemView * itemView )

Sets the view to be used in the combobox popup to the given itemView. The combobox takes ownership of the view.

See also view().

### void QComboBox::showPopup () `[virtual]`

Displays the list of items in the combobox. If the list is empty then the no items will be shown.

### const QValidator * QComboBox::validator () const

Returns the validator that is used to constrain text input for the combobox.

See also setValidator() and editable.

### QAbstractItemView * QComboBox::view () const

Returns the list view used for the combobox popup.

See also setView().