FlexibleBottomNavigationBar class

A material widget that's displayed at the bottom of an app for selecting among a small number of views, typically between three and five.

The bottom navigation bar consists of multiple items in the form of text labels, icons, or both, laid out on top of a piece of material. It provides quick navigation between the top-level views of an app. For larger screens, side navigation may be a better fit.

A bottom navigation bar is usually used in conjunction with a Scaffold, where it is provided as the Scaffold.FlexibleBottomNavigationBar argument.

The bottom navigation bar's type changes how its items are displayed. If not specified, then it's automatically set to FlexibleBottomNavigationBarType.fixed when there are less than four items, and FlexibleBottomNavigationBarType.shifting otherwise.

The length of items must be at least two and each item's icon and title/label must not be null.

• FlexibleBottomNavigationBarType.fixed, the default when there are less than four items. The selected item is rendered with the selectedItemColor if it's non-null, otherwise the theme's ColorScheme.primary color is used for Brightness.light themes and ColorScheme.secondary for Brightness.dark themes. If backgroundColor is null, The navigation bar's background color defaults to the Material background color, ThemeData.canvasColor (essentially opaque white).
• FlexibleBottomNavigationBarType.shifting, the default when there are four or more items. If selectedItemColor is null, all items are rendered in white. The navigation bar's background color is the same as the FlexibleBottomNavigationBarItem.backgroundColor of the selected item. In this case it's assumed that each item will have a different background color and that background color will contrast well with white.

{@tool dartpad} This example shows a FlexibleBottomNavigationBar as it is used within a Scaffold widget. The FlexibleBottomNavigationBar has three FlexibleBottomNavigationBarItem widgets, which means it defaults to FlexibleBottomNavigationBarType.fixed, and the currentIndex is set to index 0. The selected item is amber. The _onItemTapped function changes the selected item's index and displays a corresponding message in the center of the Scaffold.

** See code in examples/api/lib/material/bottom_navigation_bar/bottom_navigation_bar.0.dart ** {@end-tool}

{@tool dartpad} This example shows a FlexibleBottomNavigationBar as it is used within a Scaffold widget. The FlexibleBottomNavigationBar has four FlexibleBottomNavigationBarItem widgets, which means it defaults to FlexibleBottomNavigationBarType.shifting, and the currentIndex is set to index 0. The selected item is amber in color. With each FlexibleBottomNavigationBarItem widget, backgroundColor property is also defined, which changes the background color of FlexibleBottomNavigationBar, when that item is selected. The _onItemTapped function changes the selected item's index and displays a corresponding message in the center of the Scaffold.

** See code in examples/api/lib/material/bottom_navigation_bar/bottom_navigation_bar.1.dart ** {@end-tool}

{@tool dartpad} This example shows FlexibleBottomNavigationBar used in a Scaffold Widget with different interaction patterns. Tapping twice on the first FlexibleBottomNavigationBarItem uses the ScrollController to animate the ListView to the top. The second FlexibleBottomNavigationBarItem shows a Modal Dialog.

** See code in examples/api/lib/material/bottom_navigation_bar/bottom_navigation_bar.2.dart ** {@end-tool} See also:

• FlexibleBottomNavigationBarItem
• Scaffold
• material.io/design/components/bottom-navigation.html
• NavigationBar, this widget's replacement in Material Design 3.

Inheritance

• Object
• DiagnosticableTree
• Widget
• StatefulWidget
• FlexibleBottomNavigationBar

Constructors

FlexibleBottomNavigationBar({Key? key, required List<BottomNavigationBarItem> items, ValueChanged<int>? onTap, int currentIndex = 0, double? elevation, FlexibleBottomNavigationBarType? type, Color? fixedColor, Color? backgroundColor, double iconSize = 24.0, Color? selectedItemColor, Color? unselectedItemColor, IconThemeData? selectedIconTheme, IconThemeData? unselectedIconTheme, double selectedFontSize = 14.0, double unselectedFontSize = 12.0, TextStyle? selectedLabelStyle, TextStyle? unselectedLabelStyle, bool? showSelectedLabels, bool? showUnselectedLabels, MouseCursor? mouseCursor, bool? enableFeedback, BottomNavigationBarLandscapeLayout? landscapeLayout, bool useLegacyColorScheme = true})

Creates a bottom navigation bar which is typically used as a Scaffold's Scaffold.FlexibleBottomNavigationBar argument.

Properties

backgroundColor → Color?

The color of the FlexibleBottomNavigationBar itself.

final

currentIndex → int

The index into items for the current active FlexibleBottomNavigationBarItem.

final

elevation → double?

The z-coordinate of this FlexibleBottomNavigationBar.

final

enableFeedback → bool?

Whether detected gestures should provide acoustic and/or haptic feedback.

final

fixedColor → Color?

The value of selectedItemColor.

no setter

hashCode → int

The hash code for this object.

no setter, inherited

iconSize → double

The size of all of the FlexibleBottomNavigationBarItem icons.

final

items → List<BottomNavigationBarItem>

Defines the appearance of the button items that are arrayed within the bottom navigation bar.

final

key → Key?

Controls how one widget replaces another widget in the tree.

final, inherited

landscapeLayout → BottomNavigationBarLandscapeLayout?

The arrangement of the bar's items when the enclosing MediaQueryData.orientation is Orientation.landscape.

final

mouseCursor → MouseCursor?

The cursor for a mouse pointer when it enters or is hovering over the items.

final

onTap → ValueChanged<int>?

Called when one of the items is tapped.

final

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

selectedFontSize → double

The font size of the FlexibleBottomNavigationBarItem labels when they are selected.

final

selectedIconTheme → IconThemeData?

The size, opacity, and color of the icon in the currently selected FlexibleBottomNavigationBarItem.icon.

final

selectedItemColor → Color?

The color of the selected FlexibleBottomNavigationBarItem.icon and FlexibleBottomNavigationBarItem.label.

final

selectedLabelStyle → TextStyle?

The TextStyle of the FlexibleBottomNavigationBarItem labels when they are selected.

final

showSelectedLabels → bool?

Whether the labels are shown for the selected FlexibleBottomNavigationBarItem.

final

showUnselectedLabels → bool?

Whether the labels are shown for the unselected FlexibleBottomNavigationBarItems.

final

type → FlexibleBottomNavigationBarType?

Defines the layout and behavior of a FlexibleBottomNavigationBar.

final

unselectedFontSize → double

The font size of the FlexibleBottomNavigationBarItem labels when they are not selected.

final

unselectedIconTheme → IconThemeData?

The size, opacity, and color of the icon in the currently unselected FlexibleBottomNavigationBarItem.icons.

final

unselectedItemColor → Color?

The color of the unselected FlexibleBottomNavigationBarItem.icon and FlexibleBottomNavigationBarItem.labels.

final

unselectedLabelStyle → TextStyle?

The TextStyle of the FlexibleBottomNavigationBarItem labels when they are not selected.

final

useLegacyColorScheme → bool

This flag is controlling how FlexibleBottomNavigationBar is going to use the colors provided by the selectedIconTheme, unselectedIconTheme, selectedItemColor, unselectedItemColor. The default value is true as the new theming logic is a breaking change. To opt-in the new theming logic set the flag to false

final

Methods

createElement() → StatefulElement

Creates a StatefulElement to manage this widget's location in the tree.

inherited

createState() → State<FlexibleBottomNavigationBar>

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