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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 'button_theme.dart';
import 'theme.dart';
/// Defines the visual properties of [ButtonBar] widgets.
/// Used by [ButtonBarTheme] to control the visual properties of [ButtonBar]
/// instances in a widget subtree.
/// To obtain this configuration, use [ButtonBarTheme.of] to access the closest
/// ancestor [ButtonBarTheme] of the current [BuildContext].
/// See also:
/// * [ButtonBarTheme], an [InheritedWidget] that propagates the theme down
/// its subtree.
/// * [ButtonBar], which uses this to configure itself and its children
/// button widgets.
class ButtonBarThemeData with Diagnosticable {
/// Constructs the set of properties used to configure [ButtonBar] widgets.
/// Both [buttonMinWidth] and [buttonHeight] must be non-negative if they
/// are not null.
const ButtonBarThemeData({
}) : assert(buttonMinWidth == null || buttonMinWidth >= 0.0),
assert(buttonHeight == null || buttonHeight >= 0.0);
/// How the children should be placed along the horizontal axis.
final MainAxisAlignment? alignment;
/// How much horizontal space is available. See [Row.mainAxisSize].
final MainAxisSize? mainAxisSize;
/// Defines a [ButtonBar] button's base colors, and the defaults for
/// the button's minimum size, internal padding, and shape.
/// This will override the surrounding [ButtonThemeData.textTheme] setting
/// for buttons contained in the [ButtonBar].
/// Despite the name, this property is not a [TextTheme], its value is not a
/// collection of [TextStyle]s.
final ButtonTextTheme? buttonTextTheme;
/// The minimum width for [ButtonBar] buttons.
/// This will override the surrounding [ButtonThemeData.minWidth] setting
/// for buttons contained in the [ButtonBar].
/// The actual horizontal space allocated for a button's child is
/// at least this value less the theme's horizontal [ButtonThemeData.padding].
final double? buttonMinWidth;
/// The minimum height for [ButtonBar] buttons.
/// This will override the surrounding [ButtonThemeData.height] setting
/// for buttons contained in the [ButtonBar].
final double? buttonHeight;
/// Padding for a [ButtonBar] button's child (typically the button's label).
/// This will override the surrounding [ButtonThemeData.padding] setting
/// for buttons contained in the [ButtonBar].
final EdgeInsetsGeometry? buttonPadding;
/// If true, then a [DropdownButton] menu's width will match the [ButtonBar]
/// button's width.
/// If false, then the dropdown's menu will be wider than
/// its button. In either case the dropdown button will line up the leading
/// edge of the menu's value with the leading edge of the values
/// displayed by the menu items.
/// This will override the surrounding [ButtonThemeData.alignedDropdown] setting
/// for buttons contained in the [ButtonBar].
/// This property only affects [DropdownButton] contained in a [ButtonBar]
/// and its menu.
final bool? buttonAlignedDropdown;
/// Defines whether a [ButtonBar] should size itself with a minimum size
/// constraint or with padding.
final ButtonBarLayoutBehavior? layoutBehavior;
/// Defines the vertical direction of a [ButtonBar]'s children if it
/// overflows.
/// If the [ButtonBar]'s children do not fit into a single row, then they
/// are arranged in a column. The first action is at the top of the
/// column if this property is set to [VerticalDirection.down], since it
/// "starts" at the top and "ends" at the bottom. On the other hand,
/// the first action will be at the bottom of the column if this
/// property is set to [VerticalDirection.up], since it "starts" at the
/// bottom and "ends" at the top.
final VerticalDirection? overflowDirection;
/// Creates a copy of this object but with the given fields replaced with the
/// new values.
ButtonBarThemeData copyWith({
MainAxisAlignment? alignment,
MainAxisSize? mainAxisSize,
ButtonTextTheme? buttonTextTheme,
double? buttonMinWidth,
double? buttonHeight,
EdgeInsetsGeometry? buttonPadding,
bool? buttonAlignedDropdown,
ButtonBarLayoutBehavior? layoutBehavior,
VerticalDirection? overflowDirection,
}) {
return ButtonBarThemeData(
alignment: alignment ?? this.alignment,
mainAxisSize: mainAxisSize ?? this.mainAxisSize,
buttonTextTheme: buttonTextTheme ?? this.buttonTextTheme,
buttonMinWidth: buttonMinWidth ?? this.buttonMinWidth,
buttonHeight: buttonHeight ?? this.buttonHeight,
buttonPadding: buttonPadding ?? this.buttonPadding,
buttonAlignedDropdown: buttonAlignedDropdown ?? this.buttonAlignedDropdown,
layoutBehavior: layoutBehavior ?? this.layoutBehavior,
overflowDirection: overflowDirection ?? this.overflowDirection,
/// Linearly interpolate between two button bar themes.
/// If both arguments are null, then null is returned.
/// {@macro dart.ui.shadow.lerp}
static ButtonBarThemeData? lerp(ButtonBarThemeData? a, ButtonBarThemeData? b, double t) {
assert(t != null);
if (a == null && b == null)
return null;
return ButtonBarThemeData(
alignment: t < 0.5 ? a?.alignment : b?.alignment,
mainAxisSize: t < 0.5 ? a?.mainAxisSize : b?.mainAxisSize,
buttonTextTheme: t < 0.5 ? a?.buttonTextTheme : b?.buttonTextTheme,
buttonMinWidth: lerpDouble(a?.buttonMinWidth, b?.buttonMinWidth, t),
buttonHeight: lerpDouble(a?.buttonHeight, b?.buttonHeight, t),
buttonPadding: EdgeInsetsGeometry.lerp(a?.buttonPadding, b?.buttonPadding, t),
buttonAlignedDropdown: t < 0.5 ? a?.buttonAlignedDropdown : b?.buttonAlignedDropdown,
layoutBehavior: t < 0.5 ? a?.layoutBehavior : b?.layoutBehavior,
overflowDirection: t < 0.5 ? a?.overflowDirection : b?.overflowDirection,
int get hashCode {
return hashValues(
bool operator ==(Object other) {
if (identical(this, other))
return true;
if (other.runtimeType != runtimeType)
return false;
return other is ButtonBarThemeData
&& other.alignment == alignment
&& other.mainAxisSize == mainAxisSize
&& other.buttonTextTheme == buttonTextTheme
&& other.buttonMinWidth == buttonMinWidth
&& other.buttonHeight == buttonHeight
&& other.buttonPadding == buttonPadding
&& other.buttonAlignedDropdown == buttonAlignedDropdown
&& other.layoutBehavior == layoutBehavior
&& other.overflowDirection == overflowDirection;
void debugFillProperties(DiagnosticPropertiesBuilder properties) {
properties.add(DiagnosticsProperty<MainAxisAlignment>('alignment', alignment, defaultValue: null));
properties.add(DiagnosticsProperty<MainAxisSize>('mainAxisSize', mainAxisSize, defaultValue: null));
properties.add(DiagnosticsProperty<ButtonTextTheme>('textTheme', buttonTextTheme, defaultValue: null));
properties.add(DoubleProperty('minWidth', buttonMinWidth, defaultValue: null));
properties.add(DoubleProperty('height', buttonHeight, defaultValue: null));
properties.add(DiagnosticsProperty<EdgeInsetsGeometry>('padding', buttonPadding, defaultValue: null));
value: buttonAlignedDropdown,
ifTrue: 'dropdown width matches button',
defaultValue: null));
properties.add(DiagnosticsProperty<ButtonBarLayoutBehavior>('layoutBehavior', layoutBehavior, defaultValue: null));
properties.add(DiagnosticsProperty<VerticalDirection>('overflowDirection', overflowDirection, defaultValue: null));
/// Applies a button bar theme to descendant [ButtonBar] widgets.
/// A button bar theme describes the layout and properties for the buttons
/// contained in a [ButtonBar].
/// Descendant widgets obtain the current theme's [ButtonBarTheme] object using
/// [ButtonBarTheme.of]. When a widget uses [ButtonBarTheme.of], it is automatically
/// rebuilt if the theme later changes.
/// A button bar theme can be specified as part of the overall Material theme
/// using [ThemeData.buttonBarTheme].
/// See also:
/// * [ButtonBarThemeData], which describes the actual configuration of a button
/// bar theme.
class ButtonBarTheme extends InheritedWidget {
/// Constructs a button bar theme that configures all descendent [ButtonBar]
/// widgets.
/// The [data] must not be null.
const ButtonBarTheme({
Key? key,
required Widget child,
}) : assert(data != null), super(key: key, child: child);
/// The properties used for all descendant [ButtonBar] widgets.
final ButtonBarThemeData data;
/// Returns the configuration [data] from the closest [ButtonBarTheme]
/// ancestor. If there is no ancestor, it returns [ThemeData.buttonBarTheme].
/// Applications can assume that the returned value will not be null.
/// Typical usage is as follows:
/// ```dart
/// ButtonBarThemeData theme = ButtonBarTheme.of(context);
/// ```
static ButtonBarThemeData of(BuildContext context) {
final ButtonBarTheme? buttonBarTheme = context.dependOnInheritedWidgetOfExactType<ButtonBarTheme>();
return buttonBarTheme?.data ?? Theme.of(context).buttonBarTheme;
bool updateShouldNotify(ButtonBarTheme oldWidget) => data !=;