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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/widgets.dart';
import 'material_state.dart';
import 'theme.dart';
/// Defines where a [SnackBar] should appear within a [Scaffold] and how its
/// location should be adjusted when the scaffold also includes a
/// [FloatingActionButton] or a [BottomNavigationBar].
enum SnackBarBehavior {
/// Fixes the [SnackBar] at the bottom of the [Scaffold].
/// The exception is that the [SnackBar] will be shown above a
/// [BottomNavigationBar]. Additionally, the [SnackBar] will cause other
/// non-fixed widgets inside [Scaffold] to be pushed above (for example, the
/// [FloatingActionButton]).
/// This behavior will cause [SnackBar] to be shown above other widgets in the
/// [Scaffold]. This includes being displayed above a [BottomNavigationBar]
/// and a [FloatingActionButton].
/// See <> for more details.
/// Customizes default property values for [SnackBar] widgets.
/// Descendant widgets obtain the current [SnackBarThemeData] object using
/// `Theme.of(context).snackBarTheme`. Instances of [SnackBarThemeData] can be
/// customized with [SnackBarThemeData.copyWith].
/// Typically a [SnackBarThemeData] is specified as part of the overall [Theme]
/// with [ThemeData.snackBarTheme]. The default for [ThemeData.snackBarTheme]
/// provides all `null` properties.
/// All [SnackBarThemeData] properties are `null` by default. When null, the
/// [SnackBar] will provide its own defaults.
/// See also:
/// * [ThemeData], which describes the overall theme information for the
/// application.
class SnackBarThemeData with Diagnosticable {
/// Creates a theme that can be used for [ThemeData.snackBarTheme].
/// The [elevation] must be null or non-negative.
const SnackBarThemeData({
}) : assert(elevation == null || elevation >= 0.0),
assert(width == null || identical(behavior, SnackBarBehavior.floating),
'Width can only be set if behaviour is SnackBarBehavior.floating'),
assert(actionOverflowThreshold == null || (actionOverflowThreshold >= 0 && actionOverflowThreshold <= 1),
'Action overflow threshold must be between 0 and 1 inclusive'),
assert(actionBackgroundColor is! MaterialStateColor || disabledActionBackgroundColor == null,
'disabledBackgroundColor must not be provided when background color is '
'a MaterialStateColor');
/// Overrides the default value for [SnackBar.backgroundColor].
/// If null, [SnackBar] defaults to dark grey: `Color(0xFF323232)`.
final Color? backgroundColor;
/// Overrides the default value for [SnackBarAction.textColor].
/// If null, [SnackBarAction] defaults to [ColorScheme.secondary] of
/// [ThemeData.colorScheme] .
final Color? actionTextColor;
/// Overrides the default value for [SnackBarAction.disabledTextColor].
/// If null, [SnackBarAction] defaults to [ColorScheme.onSurface] with its
/// opacity set to 0.30 if the [Theme]'s brightness is [Brightness.dark], 0.38
/// otherwise.
final Color? disabledActionTextColor;
/// Used to configure the [DefaultTextStyle] for the [SnackBar.content] widget.
/// If null, [SnackBar] defines its default.
final TextStyle? contentTextStyle;
/// Overrides the default value for [SnackBar.elevation].
/// If null, [SnackBar] uses a default of 6.0.
final double? elevation;
/// Overrides the default value for [SnackBar.shape].
/// If null, [SnackBar] provides different defaults depending on the
/// [SnackBarBehavior]. For [SnackBarBehavior.fixed], no overriding shape is
/// specified, so the [SnackBar] is rectangular. For
/// [SnackBarBehavior.floating], it uses a [RoundedRectangleBorder] with a
/// circular corner radius of 4.0.
final ShapeBorder? shape;
/// Overrides the default value for [SnackBar.behavior].
/// If null, [SnackBar] will default to [SnackBarBehavior.fixed].
final SnackBarBehavior? behavior;
/// Overrides the default value for [SnackBar.width].
/// If this property is null, then the snack bar will take up the full device
/// width less the margin. This value is only used when [behavior] is
/// [SnackBarBehavior.floating].
final double? width;
/// Overrides the default value for [SnackBar.margin].
/// This value is only used when [behavior] is [SnackBarBehavior.floating].
final EdgeInsets? insetPadding;
/// Overrides the default value for [SnackBar.showCloseIcon].
/// Whether to show an optional "Close" icon.
final bool? showCloseIcon;
/// Overrides the default value for [SnackBar.closeIconColor].
/// This value is only used if [showCloseIcon] is true.
final Color? closeIconColor;
/// Overrides the default value for [SnackBar.actionOverflowThreshold].
/// Must be a value between 0 and 1, if present.
final double? actionOverflowThreshold;
/// Overrides default value for [SnackBarAction.backgroundColor].
/// If null, [SnackBarAction] falls back to [Colors.transparent].
final Color? actionBackgroundColor;
/// Overrides default value for [SnackBarAction.].
/// If null, [SnackBarAction] falls back to [Colors.transparent].
final Color? disabledActionBackgroundColor;
/// Creates a copy of this object with the given fields replaced with the
/// new values.
SnackBarThemeData copyWith({
Color? backgroundColor,
Color? actionTextColor,
Color? disabledActionTextColor,
TextStyle? contentTextStyle,
double? elevation,
ShapeBorder? shape,
SnackBarBehavior? behavior,
double? width,
EdgeInsets? insetPadding,
bool? showCloseIcon,
Color? closeIconColor,
double? actionOverflowThreshold,
Color? actionBackgroundColor,
Color? disabledActionBackgroundColor,
}) {
return SnackBarThemeData(
backgroundColor: backgroundColor ?? this.backgroundColor,
actionTextColor: actionTextColor ?? this.actionTextColor,
disabledActionTextColor: disabledActionTextColor ?? this.disabledActionTextColor,
contentTextStyle: contentTextStyle ?? this.contentTextStyle,
elevation: elevation ?? this.elevation,
shape: shape ?? this.shape,
behavior: behavior ?? this.behavior,
width: width ?? this.width,
insetPadding: insetPadding ?? this.insetPadding,
showCloseIcon: showCloseIcon ?? this.showCloseIcon,
closeIconColor: closeIconColor ?? this.closeIconColor,
actionOverflowThreshold: actionOverflowThreshold ?? this.actionOverflowThreshold,
actionBackgroundColor: actionBackgroundColor ?? this.actionBackgroundColor,
disabledActionBackgroundColor: disabledActionBackgroundColor ?? this.disabledActionBackgroundColor,
/// Linearly interpolate between two SnackBar Themes.
/// The argument `t` must not be null.
/// {@macro dart.ui.shadow.lerp}
static SnackBarThemeData lerp(SnackBarThemeData? a, SnackBarThemeData? b, double t) {
if (identical(a, b) && a != null) {
return a;
return SnackBarThemeData(
backgroundColor: Color.lerp(a?.backgroundColor, b?.backgroundColor, t),
actionTextColor: Color.lerp(a?.actionTextColor, b?.actionTextColor, t),
disabledActionTextColor: Color.lerp(a?.disabledActionTextColor, b?.disabledActionTextColor, t),
contentTextStyle: TextStyle.lerp(a?.contentTextStyle, b?.contentTextStyle, t),
elevation: lerpDouble(a?.elevation, b?.elevation, t),
shape: ShapeBorder.lerp(a?.shape, b?.shape, t),
behavior: t < 0.5 ? a?.behavior : b?.behavior,
width: lerpDouble(a?.width, b?.width, t),
insetPadding: EdgeInsets.lerp(a?.insetPadding, b?.insetPadding, t),
closeIconColor: Color.lerp(a?.closeIconColor, b?.closeIconColor, t),
actionOverflowThreshold: lerpDouble(a?.actionOverflowThreshold, b?.actionOverflowThreshold, t),
actionBackgroundColor: Color.lerp(a?.actionBackgroundColor, b?.actionBackgroundColor, t),
disabledActionBackgroundColor: Color.lerp(a?.disabledActionBackgroundColor, b?.disabledActionBackgroundColor, 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 SnackBarThemeData
&& other.backgroundColor == backgroundColor
&& other.actionTextColor == actionTextColor
&& other.disabledActionTextColor == disabledActionTextColor
&& other.contentTextStyle == contentTextStyle
&& other.elevation == elevation
&& other.shape == shape
&& other.behavior == behavior
&& other.width == width
&& other.insetPadding == insetPadding
&& other.showCloseIcon == showCloseIcon
&& other.closeIconColor == closeIconColor
&& other.actionOverflowThreshold == actionOverflowThreshold
&& other.actionBackgroundColor == actionBackgroundColor
&& other.disabledActionBackgroundColor == disabledActionBackgroundColor;
void debugFillProperties(DiagnosticPropertiesBuilder properties) {
properties.add(ColorProperty('backgroundColor', backgroundColor, defaultValue: null));
properties.add(ColorProperty('actionTextColor', actionTextColor, defaultValue: null));
properties.add(ColorProperty('disabledActionTextColor', disabledActionTextColor, defaultValue: null));
properties.add(DiagnosticsProperty<TextStyle>('contentTextStyle', contentTextStyle, defaultValue: null));
properties.add(DoubleProperty('elevation', elevation, defaultValue: null));
properties.add(DiagnosticsProperty<ShapeBorder>('shape', shape, defaultValue: null));
properties.add(DiagnosticsProperty<SnackBarBehavior>('behavior', behavior, defaultValue: null));
properties.add(DoubleProperty('width', width, defaultValue: null));
properties.add(DiagnosticsProperty<EdgeInsets>('insetPadding', insetPadding, defaultValue: null));
properties.add(DiagnosticsProperty<bool>('showCloseIcon', showCloseIcon, defaultValue: null));
properties.add(ColorProperty('closeIconColor', closeIconColor, defaultValue: null));
properties.add(DoubleProperty('actionOverflowThreshold', actionOverflowThreshold, defaultValue: null));
properties.add(ColorProperty('actionBackgroundColor', actionBackgroundColor, defaultValue: null));
properties.add(ColorProperty('disabledActionBackgroundColor', disabledActionBackgroundColor, defaultValue: null));