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// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
import 'dart:ui' show lerpDouble;
import 'package:flutter/foundation.dart';
import 'package:flutter/rendering.dart';
import 'package:flutter/widgets.dart';
import 'navigation_rail.dart';
import 'theme.dart';
// Examples can assume:
// late BuildContext context;
/// Defines default property values for descendant [NavigationRail]
/// widgets.
/// Descendant widgets obtain the current [NavigationRailThemeData] object
/// using `NavigationRailTheme.of(context)`. Instances of
/// [NavigationRailThemeData] can be customized with
/// [NavigationRailThemeData.copyWith].
/// Typically a [NavigationRailThemeData] is specified as part of the
/// overall [Theme] with [ThemeData.navigationRailTheme].
/// All [NavigationRailThemeData] properties are `null` by default.
/// When null, the [NavigationRail] will use the values from [ThemeData]
/// if they exist, otherwise it will provide its own defaults based on the
/// overall [Theme]'s textTheme and colorScheme. See the individual
/// [NavigationRail] properties for details.
/// See also:
/// * [ThemeData], which describes the overall theme information for the
/// application.
class NavigationRailThemeData with Diagnosticable {
/// Creates a theme that can be used for [ThemeData.navigationRailTheme].
const NavigationRailThemeData({
/// Color to be used for the [NavigationRail]'s background.
final Color? backgroundColor;
/// The z-coordinate to be used for the [NavigationRail]'s elevation.
final double? elevation;
/// The style to merge with the default text style for
/// [NavigationRailDestination] labels, when the destination is not selected.
final TextStyle? unselectedLabelTextStyle;
/// The style to merge with the default text style for
/// [NavigationRailDestination] labels, when the destination is selected.
final TextStyle? selectedLabelTextStyle;
/// The theme to merge with the default icon theme for
/// [NavigationRailDestination] icons, when the destination is not selected.
final IconThemeData? unselectedIconTheme;
/// The theme to merge with the default icon theme for
/// [NavigationRailDestination] icons, when the destination is selected.
final IconThemeData? selectedIconTheme;
/// The alignment for the [NavigationRailDestination]s as they are positioned
/// within the [NavigationRail].
final double? groupAlignment;
/// The type that defines the layout and behavior of the labels in the
/// [NavigationRail].
final NavigationRailLabelType? labelType;
/// Whether or not the selected [NavigationRailDestination] should include a
/// [NavigationIndicator].
final bool? useIndicator;
/// Overrides the default value of [NavigationRail]'s selection indicator color,
/// when [useIndicator] is true.
final Color? indicatorColor;
/// Overrides the default shape of the [NavigationRail]'s selection indicator.
final ShapeBorder? indicatorShape;
/// Overrides the default value of [NavigationRail]'s minimum width when it
/// is not extended.
final double? minWidth;
/// Overrides the default value of [NavigationRail]'s minimum width when it
/// is extended.
final double? minExtendedWidth;
/// Creates a copy of this object with the given fields replaced with the
/// new values.
NavigationRailThemeData copyWith({
Color? backgroundColor,
double? elevation,
TextStyle? unselectedLabelTextStyle,
TextStyle? selectedLabelTextStyle,
IconThemeData? unselectedIconTheme,
IconThemeData? selectedIconTheme,
double? groupAlignment,
NavigationRailLabelType? labelType,
bool? useIndicator,
Color? indicatorColor,
ShapeBorder? indicatorShape,
double? minWidth,
double? minExtendedWidth,
}) {
return NavigationRailThemeData(
backgroundColor: backgroundColor ?? this.backgroundColor,
elevation: elevation ?? this.elevation,
unselectedLabelTextStyle: unselectedLabelTextStyle ?? this.unselectedLabelTextStyle,
selectedLabelTextStyle: selectedLabelTextStyle ?? this.selectedLabelTextStyle,
unselectedIconTheme: unselectedIconTheme ?? this.unselectedIconTheme,
selectedIconTheme: selectedIconTheme ?? this.selectedIconTheme,
groupAlignment: groupAlignment ?? this.groupAlignment,
labelType: labelType ?? this.labelType,
useIndicator: useIndicator ?? this.useIndicator,
indicatorColor: indicatorColor ?? this.indicatorColor,
indicatorShape: indicatorShape ?? this.indicatorShape,
minWidth: minWidth ?? this.minWidth,
minExtendedWidth: minExtendedWidth ?? this.minExtendedWidth,
/// Linearly interpolate between two navigation rail themes.
/// If both arguments are null then null is returned.
/// {@macro dart.ui.shadow.lerp}
static NavigationRailThemeData? lerp(NavigationRailThemeData? a, NavigationRailThemeData? b, double t) {
if (identical(a, b)) {
return a;
return NavigationRailThemeData(
backgroundColor: Color.lerp(a?.backgroundColor, b?.backgroundColor, t),
elevation: lerpDouble(a?.elevation, b?.elevation, t),
unselectedLabelTextStyle: TextStyle.lerp(a?.unselectedLabelTextStyle, b?.unselectedLabelTextStyle, t),
selectedLabelTextStyle: TextStyle.lerp(a?.selectedLabelTextStyle, b?.selectedLabelTextStyle, t),
unselectedIconTheme: a?.unselectedIconTheme == null && b?.unselectedIconTheme == null
? null : IconThemeData.lerp(a?.unselectedIconTheme, b?.unselectedIconTheme, t),
selectedIconTheme: a?.selectedIconTheme == null && b?.selectedIconTheme == null
? null : IconThemeData.lerp(a?.selectedIconTheme, b?.selectedIconTheme, t),
groupAlignment: lerpDouble(a?.groupAlignment, b?.groupAlignment, t),
labelType: t < 0.5 ? a?.labelType : b?.labelType,
useIndicator: t < 0.5 ? a?.useIndicator : b?.useIndicator,
indicatorColor: Color.lerp(a?.indicatorColor, b?.indicatorColor, t),
indicatorShape: ShapeBorder.lerp(a?.indicatorShape, b?.indicatorShape, t),
minWidth: lerpDouble(a?.minWidth, b?.minWidth, t),
minExtendedWidth: lerpDouble(a?.minExtendedWidth, b?.minExtendedWidth, t),
int get hashCode => Object.hash(
bool operator ==(Object other) {
if (identical(this, other)) {
return true;
if (other.runtimeType != runtimeType) {
return false;
return other is NavigationRailThemeData
&& other.backgroundColor == backgroundColor
&& other.elevation == elevation
&& other.unselectedLabelTextStyle == unselectedLabelTextStyle
&& other.selectedLabelTextStyle == selectedLabelTextStyle
&& other.unselectedIconTheme == unselectedIconTheme
&& other.selectedIconTheme == selectedIconTheme
&& other.groupAlignment == groupAlignment
&& other.labelType == labelType
&& other.useIndicator == useIndicator
&& other.indicatorColor == indicatorColor
&& other.indicatorShape == indicatorShape
&& other.minWidth == minWidth
&& other.minExtendedWidth == minExtendedWidth;
void debugFillProperties(DiagnosticPropertiesBuilder properties) {
const NavigationRailThemeData defaultData = NavigationRailThemeData();
properties.add(ColorProperty('backgroundColor', backgroundColor, defaultValue: defaultData.backgroundColor));
properties.add(DoubleProperty('elevation', elevation, defaultValue: defaultData.elevation));
properties.add(DiagnosticsProperty<TextStyle>('unselectedLabelTextStyle', unselectedLabelTextStyle, defaultValue: defaultData.unselectedLabelTextStyle));
properties.add(DiagnosticsProperty<TextStyle>('selectedLabelTextStyle', selectedLabelTextStyle, defaultValue: defaultData.selectedLabelTextStyle));
properties.add(DiagnosticsProperty<IconThemeData>('unselectedIconTheme', unselectedIconTheme, defaultValue: defaultData.unselectedIconTheme));
properties.add(DiagnosticsProperty<IconThemeData>('selectedIconTheme', selectedIconTheme, defaultValue: defaultData.selectedIconTheme));
properties.add(DoubleProperty('groupAlignment', groupAlignment, defaultValue: defaultData.groupAlignment));
properties.add(DiagnosticsProperty<NavigationRailLabelType>('labelType', labelType, defaultValue: defaultData.labelType));
properties.add(DiagnosticsProperty<bool>('useIndicator', useIndicator, defaultValue: defaultData.useIndicator));
properties.add(ColorProperty('indicatorColor', indicatorColor, defaultValue: defaultData.indicatorColor));
properties.add(DiagnosticsProperty<ShapeBorder>('indicatorShape', indicatorShape, defaultValue: null));
properties.add(DoubleProperty('minWidth', minWidth, defaultValue: defaultData.minWidth));
properties.add(DoubleProperty('minExtendedWidth', minExtendedWidth, defaultValue: defaultData.minExtendedWidth));
/// An inherited widget that defines visual properties for [NavigationRail]s and
/// [NavigationRailDestination]s in this widget's subtree.
/// Values specified here are used for [NavigationRail] properties that are not
/// given an explicit non-null value.
class NavigationRailTheme extends InheritedTheme {
/// Creates a navigation rail theme that controls the
/// [NavigationRailThemeData] properties for a [NavigationRail].
/// The data argument must not be null.
const NavigationRailTheme({
required super.child,
/// Specifies the background color, elevation, label text style, icon theme,
/// group alignment, and label type and border values for descendant
/// [NavigationRail] widgets.
final NavigationRailThemeData data;
/// The closest instance of this class that encloses the given context.
/// If there is no enclosing [NavigationRailTheme] widget, then
/// [ThemeData.navigationRailTheme] is used.
/// Typical usage is as follows:
/// ```dart
/// NavigationRailThemeData theme = NavigationRailTheme.of(context);
/// ```
static NavigationRailThemeData of(BuildContext context) {
final NavigationRailTheme? navigationRailTheme = context.dependOnInheritedWidgetOfExactType<NavigationRailTheme>();
return navigationRailTheme?.data ?? Theme.of(context).navigationRailTheme;
Widget wrap(BuildContext context, Widget child) {
return NavigationRailTheme(data: data, child: child);
bool updateShouldNotify(NavigationRailTheme oldWidget) => data !=;