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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 '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);
/// Default value for [SnackBar.backgroundColor].
/// If null, [SnackBar] defaults to dark grey: `Color(0xFF323232)`.
final Color? backgroundColor;
/// Default value for [SnackBarAction.textColor].
/// If null, [SnackBarAction] defaults to [ColorScheme.secondary] of
/// [ThemeData.colorScheme] .
final Color? actionTextColor;
/// 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;
/// Default value for [SnackBar.elevation].
/// If null, [SnackBar] uses a default of 6.0.
final double? elevation;
/// 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;
/// Default value for [SnackBar.behavior].
/// If null, [SnackBar] will default to [SnackBarBehavior.fixed].
final SnackBarBehavior? behavior;
/// 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,
}) {
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,
/// 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) {
assert(t != null);
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,
int get hashCode {
return hashValues(
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;
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));