DropdownButton<T> class

An interactive select menu button that opens a dropdown list overlay.

Interaction Modes

Keyboard: When focused, opens using Space, Enter, or Down Arrow. Once open, navigate choices using Up/Down arrow keys, select using Enter or Space, and close/cancel using Escape.
Mouse: Left-clicking opens the menu; clicking an item selects it.

Absolute Portal Mapping

The dropdown uses getAbsoluteRect to resolve its button boundaries within nested viewports, ensuring the floating overlay list maps to absolute screen coordinates directly beneath the button, bypassing child clipping.

Example Usage

DropdownButton<String>(
  value: selectedFruit,
  items: const [
    DropdownMenuItem(value: 'apple', child: Text('Apple')),
    DropdownMenuItem(value: 'banana', child: Text('Banana')),
  ],
  onChanged: (val) {
    setState(() => selectedFruit = val);
  },
);

Properties Table

Property	Type	Description
`items`	List<DropdownMenuItem>	List of options available in the dropdown.
`value`	`T`?	The currently selected value.
`onChanged`	`Function(T?)`	Callback fired when a selection is made.
`focused`	bool	Whether this button has keyboard focus.
`dropdownStyle`	Style	Style applied to items in the dropdown menu.

Inheritance

Object
Widget
StatefulWidget
DropdownButton

Constructors

DropdownButton({required List<DropdownMenuItem<T>> items, T? value, void onChanged(T? newValue)?, Widget? hint, Style style = Style.empty, Style dropdownStyle = const Style(modifiers: Modifier.reverse), bool focused = false}): Creates a new dropdown button.
const

Properties

dropdownStyle → Style: The style applied to the dropdown menu items.
final
focused → bool: Whether the button is currently focused.
final
hashCode → int: The hash code for this object.
no setterinherited
hint → Widget?: An optional widget to display when no item is selected.
final
items → List<DropdownMenuItem<T>>: The list of items to display in the dropdown.
final
key → Key?: The optional key for this widget.
finalinherited
onChanged → void Function(T? newValue)?: Callback triggered when a new value is selected.
final
runtimeType → Type: A representation of the runtime type of the object.
no setterinherited
style → Style: The base style for the dropdown button.
final
value → T?: The currently selected value.
final

Methods

createElement() → Element: Creates an Element to manage this widget's location in the tree.
inherited
createState() → State<DropdownButton<T>>: Creates the mutable state for this widget at a given location in the tree.
override
getIntrinsicHeight(int width) → int: Computes the intrinsic height of this widget under the given width constraint.
inherited
noSuchMethod(Invocation invocation) → dynamic: Invoked when a nonexistent method or property is accessed.
inherited
render(Buffer buffer, Rect area) → void: Renders the widget onto the provided buffer within the specified area.
inherited
toString() → String: A string representation of this object.
inherited

Operators

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