ComboBox<T> class

A fluent design button for selecting from a list of items.

A combo box button lets the user select from a number of items. The button shows the currently selected item as well as an arrow that opens a menu for selecting another item.

ComboBox Popup preview

The type T is the type of the value that each combo box item represents. All the entries in a given menu must represent values with consistent types. Typically, an enum is used. Each ComboBoxItem in items must be specialized with that same type argument.

The onChanged callback should update a state variable that defines the combo box's value. It should also call State.setState to rebuild the combo box with the new value.

If the onChanged callback is null or the list of items is null then the combo box button will be disabled, i.e. its arrow will be displayed in grey and it will not respond to input. A disabled button will display the disabledPlaceholder widget if it is non-null. However, if disabledPlaceholder is null and placeholder is non-null, the placeholder widget will instead be displayed.

Requires one of its ancestors to be a Material widget.

See also:

Inheritance
Implementers
Available Extensions

Constructors

ComboBox({Key? key, required List<ComboBoxItem<T>>? items, ComboBoxBuilder? selectedItemBuilder, T? value, Widget? placeholder, Widget? disabledPlaceholder, ValueChanged<T?>? onChanged, VoidCallback? onTap, int elevation = 8, TextStyle? style, Widget icon = const Icon(FluentIcons.chevron_down), Color? iconDisabledColor, Color? iconEnabledColor, double iconSize = 8.0, bool isExpanded = false, Color? focusColor, FocusNode? focusNode, bool autofocus = false, Color? popupColor})
Creates a combo box button.
const

Properties

autofocus → bool
True if this widget will be selected as the initial focus when no other node in its scope is currently focused.
final
disabledPlaceholder → Widget?
A preferred placeholder widget that is displayed when the combo box is disabled.
final
elevation → int
The z-coordinate at which to place the menu when open.
final
focusColor → Color?
The color for the button's Material when it has the input focus.
final
focusNode → FocusNode?
An optional focus node to use as the focus node for this widget.
final
hashCode → int
The hash code for this object.
no setterinherited
icon → Widget
The widget to use for the comobo box button's icon.
final
iconDisabledColor → Color?
The color of any Icon descendant of icon if this button is disabled, i.e. if onChanged is null.
final
iconEnabledColor → Color?
The color of any Icon descendant of icon if this button is enabled, i.e. if onChanged is defined.
final
iconSize → double
The size to use for the checkbox button's down arrow icon button.
final
isExpanded → bool
Set the combo box's inner contents to horizontally fill its parent.
final
items → List<ComboBoxItem<T>>?
The list of items the user can select.
final
key → Key?
Controls how one widget replaces another widget in the tree.
finalinherited
onChanged → ValueChanged<T?>?
Called when the user selects an item.
final
onTap → VoidCallback?
Called when the combo box button is tapped.
final
placeholder → Widget?
A placeholder widget that is displayed by the combo box button.
final
popupColor → Color?
The background color of the combo box menu.
final
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
selectedItemBuilder → ComboBoxBuilder?
A builder to customize the combo box buttons corresponding to the ComboBoxItems in items.
final
style → TextStyle?
The text style to use for text in the combo box button and the combo box menu that appears when you tap the button.
final
value → T?
The value of the currently selected ComboBoxItem.
final

Methods

createElement() → StatefulElement
Creates a StatefulElement to manage this widget's location in the tree.
inherited
createState() → State<ComboBox<T>>
Creates the mutable state for this widget at a given location in the tree.
override
debugDescribeChildren() → List<DiagnosticsNode>
Returns a list of DiagnosticsNode objects describing this node's children.
inherited
debugFillProperties(DiagnosticPropertiesBuilder properties) → void
Add additional properties associated with the node.
inherited
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
toDiagnosticsNode({String? name, DiagnosticsTreeStyle? style}) → DiagnosticsNode
Returns a debug representation of the object that is used by debugging tools and by DiagnosticsNode.toStringDeep.
inherited
toString({DiagnosticLevel minLevel = DiagnosticLevel.info}) → String
A string representation of this object.
inherited
toStringDeep({String prefixLineOne = '', String? prefixOtherLines, DiagnosticLevel minLevel = DiagnosticLevel.debug}) → String
Returns a string representation of this node and its descendants.
inherited
toStringShallow({String joiner = ', ', DiagnosticLevel minLevel = DiagnosticLevel.debug}) → String
Returns a one-line detailed description of the object.
inherited
toStringShort() → String
A short, textual description of this widget.
inherited

Operators

operator ==(Object other) → bool
The equality operator.
inherited