const AnimationStyle (flutter#160564)

[**AnimationStyle**](https://main-api.flutter.dev/flutter/animation/AnimationStyle-class.html)
is an
[`@immutable`](https://main-api.flutter.dev/flutter/meta/immutable-constant.html)
class with all `final` fields.

This pull request gives it a `const` constructor.

<br>

related: flutter#160563

Author: nate-thegrate

examples/api/lib/material/app/app.0.dart

@@ -51,9 +51,9 @@ class _MaterialAppExampleState extends State<MaterialAppExample> {
                       case AnimationStyles.defaultStyle:
                         _animationStyle = null;
                       case AnimationStyles.custom:
-                        _animationStyle = AnimationStyle(
+                        _animationStyle = const AnimationStyle(
                           curve: Easing.emphasizedAccelerate,
-                          duration: const Duration(seconds: 1),
+                          duration: Duration(seconds: 1),
                         );
                       case AnimationStyles.none:
                         _animationStyle = AnimationStyle.noAnimation;

examples/api/lib/material/bottom_sheet/show_bottom_sheet.0.dart

@@ -53,9 +53,9 @@ class _BottomSheetExampleState extends State<BottomSheetExample> {
               setState(() {
                 _animationStyle = switch (styles.first) {
                   AnimationStyles.defaultStyle => null,
-                  AnimationStyles.custom => AnimationStyle(
-                    duration: const Duration(seconds: 3),
-                    reverseDuration: const Duration(seconds: 1),
+                  AnimationStyles.custom => const AnimationStyle(
+                    duration: Duration(seconds: 3),
+                    reverseDuration: Duration(seconds: 1),
                   ),
                   AnimationStyles.none => AnimationStyle.noAnimation,
                 };

examples/api/lib/material/bottom_sheet/show_modal_bottom_sheet.2.dart

@@ -53,9 +53,9 @@ class _ModalBottomSheetExampleState extends State<ModalBottomSheetExample> {
               setState(() {
                 _animationStyle = switch (styles.first) {
                   AnimationStyles.defaultStyle => null,
-                  AnimationStyles.custom => AnimationStyle(
-                    duration: const Duration(seconds: 3),
-                    reverseDuration: const Duration(seconds: 1),
+                  AnimationStyles.custom => const AnimationStyle(
+                    duration: Duration(seconds: 3),
+                    reverseDuration: Duration(seconds: 1),
                   ),
                   AnimationStyles.none => AnimationStyle.noAnimation,
                 };

examples/api/lib/material/chip/chip_attributes.chip_animation_style.0.dart

@@ -43,9 +43,9 @@ class _ChipAnimationStyleExampleState extends State<ChipAnimationStyleExample> {
               children: <Widget>[
                 FilterChip.elevated(
                   chipAnimationStyle: ChipAnimationStyle(
-                    enableAnimation: AnimationStyle(
-                      duration: const Duration(seconds: 3),
-                      reverseDuration: const Duration(seconds: 1),
+                    enableAnimation: const AnimationStyle(
+                      duration: Duration(seconds: 3),
+                      reverseDuration: Duration(seconds: 1),
                     ),
                   ),
                   onSelected: !enabled ? null : (bool value) {},
@@ -69,9 +69,9 @@ class _ChipAnimationStyleExampleState extends State<ChipAnimationStyleExample> {
               children: <Widget>[
                 FilterChip.elevated(
                   chipAnimationStyle: ChipAnimationStyle(
-                    selectAnimation: AnimationStyle(
-                      duration: const Duration(seconds: 3),
-                      reverseDuration: const Duration(seconds: 1),
+                    selectAnimation: const AnimationStyle(
+                      duration: Duration(seconds: 3),
+                      reverseDuration: Duration(seconds: 1),
                     ),
                   ),
                   backgroundColor: Colors.amber,
@@ -102,9 +102,9 @@ class _ChipAnimationStyleExampleState extends State<ChipAnimationStyleExample> {
               children: <Widget>[
                 FilterChip.elevated(
                   chipAnimationStyle: ChipAnimationStyle(
-                    avatarDrawerAnimation: AnimationStyle(
-                      duration: const Duration(seconds: 2),
-                      reverseDuration: const Duration(seconds: 1),
+                    avatarDrawerAnimation: const AnimationStyle(
+                      duration: Duration(seconds: 2),
+                      reverseDuration: Duration(seconds: 1),
                     ),
                   ),
                   selected: showCheckmark,
@@ -127,9 +127,9 @@ class _ChipAnimationStyleExampleState extends State<ChipAnimationStyleExample> {
               children: <Widget>[
                 FilterChip.elevated(
                   chipAnimationStyle: ChipAnimationStyle(
-                    deleteDrawerAnimation: AnimationStyle(
-                      duration: const Duration(seconds: 2),
-                      reverseDuration: const Duration(seconds: 1),
+                    deleteDrawerAnimation: const AnimationStyle(
+                      duration: Duration(seconds: 2),
+                      reverseDuration: Duration(seconds: 1),
                     ),
                   ),
                   onDeleted: showDeleteIcon ? () {} : null,

examples/api/lib/material/expansion_tile/expansion_tile.2.dart

@@ -46,7 +46,7 @@ class _ExpansionTileAnimationStyleAppState extends State<ExpansionTileAnimationS
                       case AnimationStyles.defaultStyle:
                         _animationStyle = null;
                       case AnimationStyles.custom:
-                        _animationStyle = AnimationStyle(
+                        _animationStyle = const AnimationStyle(
                           curve: Easing.emphasizedAccelerate,
                           duration: Durations.extralong1,
                         );

examples/api/lib/material/popup_menu/popup_menu.2.dart

@@ -59,9 +59,9 @@ class _PopupMenuExampleState extends State<PopupMenuExample> {
                         case AnimationStyles.defaultStyle:
                           _animationStyle = null;
                         case AnimationStyles.custom:
-                          _animationStyle = AnimationStyle(
+                          _animationStyle = const AnimationStyle(
                             curve: Easing.emphasizedDecelerate,
-                            duration: const Duration(seconds: 3),
+                            duration: Duration(seconds: 3),
                           );
                         case AnimationStyles.none:
                           _animationStyle = AnimationStyle.noAnimation;

examples/api/lib/material/scaffold/scaffold_messenger_state.show_snack_bar.2.dart

@@ -50,9 +50,9 @@ class _SnackBarExampleState extends State<SnackBarExample> {
                 setState(() {
                   _animationStyle = switch (styles.first) {
                     AnimationStyles.defaultStyle => null,
-                    AnimationStyles.custom => AnimationStyle(
-                      duration: const Duration(seconds: 3),
-                      reverseDuration: const Duration(seconds: 1),
+                    AnimationStyles.custom => const AnimationStyle(
+                      duration: Duration(seconds: 3),
+                      reverseDuration: Duration(seconds: 1),
                     ),
                     AnimationStyles.none => AnimationStyle.noAnimation,
                   };

examples/api/lib/material/scaffold/scaffold_state.show_bottom_sheet.1.dart

@@ -53,9 +53,9 @@ class _ShowBottomSheetExampleState extends State<ShowBottomSheetExample> {
               setState(() {
                 _animationStyle = switch (styles.first) {
                   AnimationStyles.defaultStyle => null,
-                  AnimationStyles.custom => AnimationStyle(
-                    duration: const Duration(seconds: 3),
-                    reverseDuration: const Duration(seconds: 1),
+                  AnimationStyles.custom => const AnimationStyle(
+                    duration: Duration(seconds: 3),
+                    reverseDuration: Duration(seconds: 1),
                   ),
                   AnimationStyles.none => AnimationStyle.noAnimation,
                 };

packages/flutter/lib/src/animation/animation_style.dart

@@ -28,10 +28,10 @@ import 'tween.dart';
 @immutable
 class AnimationStyle with Diagnosticable {
   /// Creates an instance of Animation Style class.
-  AnimationStyle({this.curve, this.duration, this.reverseCurve, this.reverseDuration});
+  const AnimationStyle({this.curve, this.duration, this.reverseCurve, this.reverseDuration});
 
   /// Creates an instance of Animation Style class with no animation.
-  static AnimationStyle noAnimation = AnimationStyle(
+  static const AnimationStyle noAnimation = AnimationStyle(
     duration: Duration.zero,
     reverseDuration: Duration.zero,
   );

packages/flutter/lib/src/widgets/sliver_tree.dart

@@ -490,7 +490,7 @@ class TreeSliver<T> extends StatefulWidget {
 
   /// The default [AnimationStyle] used for node expand and collapse animations,
   /// when one has not been provided in [toggleAnimationStyle].
-  static AnimationStyle defaultToggleAnimationStyle = AnimationStyle(
+  static AnimationStyle defaultToggleAnimationStyle = const AnimationStyle(
     curve: defaultAnimationCurve,
     duration: defaultAnimationDuration,
   );