Add support for M3 motion (#129942)

## Description

This adds support for M3 easing and duration tokens.

This PR includes these changes:
* Generation of duration and easing constants, in `Durations` and
`Easing`, respectively (`Curves` is already taken in the `animation`
library)
* Add 3 Dart fixes

Once this is merged, I'll migrate packages/plugins/customers and then
uncomment the deprecation notices for the 3 M2 curves, all of which have
1:1 replacements.

## Related Issues
 - Fixes #116525

## Tests
 - Added Dart fix tests

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [x] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel
on [Discord].

<!-- Links -->
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https://github.com/flutter/flutter/wiki/Tree-hygiene#overview
[Tree Hygiene]: https://github.com/flutter/flutter/wiki/Tree-hygiene
[test-exempt]:
https://github.com/flutter/flutter/wiki/Tree-hygiene#tests
[Flutter Style Guide]:
https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo
[Features we expect every widget to implement]:
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[CLA]: https://cla.developers.google.com/
[flutter/tests]: https://github.com/flutter/tests
[breaking change policy]:
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dev/tools/gen_defaults/bin/gen_defaults.dart

@@ -37,6 +37,7 @@ import 'package:gen_defaults/input_chip_template.dart';
 import 'package:gen_defaults/input_decorator_template.dart';
 import 'package:gen_defaults/list_tile_template.dart';
 import 'package:gen_defaults/menu_template.dart';
+import 'package:gen_defaults/motion_template.dart';
 import 'package:gen_defaults/navigation_bar_template.dart';
 import 'package:gen_defaults/navigation_drawer_template.dart';
 import 'package:gen_defaults/navigation_rail_template.dart';
@@ -131,6 +132,7 @@ Future<void> main(List<String> args) async {
   ListTileTemplate('LisTile', '$materialLib/list_tile.dart', tokens).updateFile();
   InputDecoratorTemplate('InputDecorator', '$materialLib/input_decorator.dart', tokens).updateFile();
   MenuTemplate('Menu', '$materialLib/menu_anchor.dart', tokens).updateFile();
+  MotionTemplate('Motion', '$materialLib/motion.dart', tokens, tokenLogger).updateFile();
   NavigationBarTemplate('NavigationBar', '$materialLib/navigation_bar.dart', tokens).updateFile();
   NavigationDrawerTemplate('NavigationDrawer', '$materialLib/navigation_drawer.dart', tokens).updateFile();
   NavigationRailTemplate('NavigationRail', '$materialLib/navigation_rail.dart', tokens).updateFile();

dev/tools/gen_defaults/generated/used_tokens.csv

@@ -856,6 +856,31 @@ md.sys.elevation.level2,
 md.sys.elevation.level3,
 md.sys.elevation.level4,
 md.sys.elevation.level5,
+md.sys.motion.duration.extra-long1Ms,
+md.sys.motion.duration.extra-long2Ms,
+md.sys.motion.duration.extra-long3Ms,
+md.sys.motion.duration.extra-long4Ms,
+md.sys.motion.duration.long1Ms,
+md.sys.motion.duration.long2Ms,
+md.sys.motion.duration.long3Ms,
+md.sys.motion.duration.long4Ms,
+md.sys.motion.duration.medium1Ms,
+md.sys.motion.duration.medium2Ms,
+md.sys.motion.duration.medium3Ms,
+md.sys.motion.duration.medium4Ms,
+md.sys.motion.duration.short1Ms,
+md.sys.motion.duration.short2Ms,
+md.sys.motion.duration.short3Ms,
+md.sys.motion.duration.short4Ms,
+md.sys.motion.easing.emphasized.accelerate,
+md.sys.motion.easing.emphasized.decelerate,
+md.sys.motion.easing.legacy,
+md.sys.motion.easing.legacy.accelerate,
+md.sys.motion.easing.legacy.decelerate,
+md.sys.motion.easing.linear,
+md.sys.motion.easing.standard,
+md.sys.motion.easing.standard.accelerate,
+md.sys.motion.easing.standard.decelerate,
 md.sys.shape.corner.extra-large,
 md.sys.shape.corner.extra-large.top,
 md.sys.shape.corner.extra-small,

dev/tools/gen_defaults/lib/motion_template.dart

@@ -0,0 +1,90 @@
+// 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 'template.dart';
+import 'token_logger.dart';
+
+class MotionTemplate extends TokenTemplate {
+  /// Since we generate the tokens dynamically, we need to store them and log
+  /// them manually, instead of using [getToken].
+  MotionTemplate(String blockName, String fileName, this.tokens, this.tokensLogger) : super(blockName, fileName, tokens);
+  Map<String, dynamic> tokens;
+  TokenLogger tokensLogger;
+
+  // List of duration tokens.
+  late List<MapEntry<String, dynamic>> durationTokens = tokens.entries.where(
+    (MapEntry<String, dynamic> entry) => entry.key.contains('.duration.')
+  ).toList()
+  ..sort(
+    (MapEntry<String, dynamic> a, MapEntry<String, dynamic> b) => (a.value as double).compareTo(b.value as double)
+  );
+
+  // List of easing curve tokens.
+  late List<MapEntry<String, dynamic>> easingCurveTokens = tokens.entries.where(
+    (MapEntry<String, dynamic> entry) => entry.key.contains('.easing.')
+  ).toList()
+  ..sort(
+    // Sort the legacy curves at the end of the list.
+    (MapEntry<String, dynamic> a, MapEntry<String, dynamic> b) => a.key.contains('legacy') ? 1 : a.key.compareTo(b.key)
+  );
+
+  String durationTokenString(String token, dynamic tokenValue) {
+    tokensLogger.log(token);
+    final String tokenName = token.split('.').last.replaceAll('-', '').replaceFirst('Ms', '');
+    final int milliseconds = (tokenValue as double).toInt();
+    return
+'''
+  /// The $tokenName duration (${milliseconds}ms) in the Material specification.
+  ///
+  /// See also:
+  ///
+  /// * [M3 guidelines: Duration tokens](https://m3.material.io/styles/motion/easing-and-duration/tokens-specs#c009dec6-f29b-4503-b9f0-482af14a8bbd)
+  /// * [M3 guidelines: Applying easing and duration](https://m3.material.io/styles/motion/easing-and-duration/applying-easing-and-duration)
+  static const Duration $tokenName = Duration(milliseconds: $milliseconds);
+''';
+  }
+
+  String easingCurveTokenString(String token, dynamic tokenValue) {
+    tokensLogger.log(token);
+    final String tokenName = token
+      .replaceFirst('md.sys.motion.easing.', '')
+      .replaceAllMapped(RegExp(r'[-\.](\w)'), (Match match) {
+        return match.group(1)!.toUpperCase();
+      });
+    return '''
+  /// The $tokenName easing curve in the Material specification.
+  ///
+  /// See also:
+  ///
+  /// * [M3 guidelines: Easing tokens](https://m3.material.io/styles/motion/easing-and-duration/tokens-specs#433b1153-2ea3-4fe2-9748-803a47bc97ee)
+  /// * [M3 guidelines: Applying easing and duration](https://m3.material.io/styles/motion/easing-and-duration/applying-easing-and-duration)
+  static const Curve $tokenName = $tokenValue;
+''';
+  }
+
+  @override
+  String generate() => '''
+/// The set of durations in the Material specification.
+///
+/// See also:
+///
+/// * [M3 guidelines: Duration tokens](https://m3.material.io/styles/motion/easing-and-duration/tokens-specs#c009dec6-f29b-4503-b9f0-482af14a8bbd)
+/// * [M3 guidelines: Applying easing and duration](https://m3.material.io/styles/motion/easing-and-duration/applying-easing-and-duration)
+abstract final class Durations {
+${durationTokens.map((MapEntry<String, dynamic> entry) => durationTokenString(entry.key, entry.value)).join('\n')}}
+
+
+// TODO(guidezpl): Improve with description and assets, b/289870605
+
+/// The set of easing curves in the Material specification.
+///
+/// See also:
+///
+/// * [M3 guidelines: Easing tokens](https://m3.material.io/styles/motion/easing-and-duration/tokens-specs#433b1153-2ea3-4fe2-9748-803a47bc97ee)
+/// * [M3 guidelines: Applying easing and duration](https://m3.material.io/styles/motion/easing-and-duration/applying-easing-and-duration)
+/// * [Curves], for a collection of non-Material animation easing curves.
+abstract final class Easing {
+${easingCurveTokens.map((MapEntry<String, dynamic> entry) => easingCurveTokenString(entry.key, entry.value)).join('\n')}}
+''';
+}

packages/flutter/lib/fix_data/fix_material/fix_material.yaml

@@ -897,4 +897,43 @@ transforms:
         oldName: 'showTrackOnHover'
         newName: 'trackVisibility'
 
+  # Changes made in https://github.com/flutter/flutter/pull/129942
+  - title: "Migrate to 'Easing.legacy'"
+    date: 2023-07-04
+    element:
+      uris: [ 'material.dart' ]
+      variable: 'standardEasing'
+    changes:
+      - kind: 'replacedBy'
+        newElement:
+          uris: [ 'material.dart' ]
+          field: legacy
+          inClass: Easing
+
+  # Changes made in https://github.com/flutter/flutter/pull/129942
+  - title: "Migrate to 'Easing.legacyAccelerate'"
+    date: 2023-07-04
+    element:
+      uris: [ 'material.dart' ]
+      variable: 'accelerateEasing'
+    changes:
+      - kind: 'replacedBy'
+        newElement:
+          uris: [ 'material.dart' ]
+          field: legacyAccelerate
+          inClass: Easing
+
+  # Changes made in https://github.com/flutter/flutter/pull/129942
+  - title: "Migrate to 'Easing.legacyDecelerate'"
+    date: 2023-07-04
+    element:
+      uris: [ 'material.dart' ]
+      variable: 'decelerateEasing'
+    changes:
+      - kind: 'replacedBy'
+        newElement:
+          uris: [ 'material.dart' ]
+          field: legacyDecelerate
+          inClass: Easing
+
 # Before adding a new fix: read instructions at the top of this file.

packages/flutter/lib/material.dart

@@ -122,6 +122,7 @@ export 'src/material/menu_button_theme.dart';
 export 'src/material/menu_style.dart';
 export 'src/material/menu_theme.dart';
 export 'src/material/mergeable_material.dart';
+export 'src/material/motion.dart';
 export 'src/material/navigation_bar.dart';
 export 'src/material/navigation_bar_theme.dart';
 export 'src/material/navigation_drawer.dart';

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

@@ -1354,6 +1354,7 @@ class ElasticInOutCurve extends Curve {
 ///
 ///  * [Curve], the interface implemented by the constants available from the
 ///    [Curves] class.
+///  * [Easing], for the Material animation curves.
 abstract final class Curves {
   /// A linear animation curve.
   ///
@@ -1741,7 +1742,7 @@ abstract final class Curves {
   ///
   /// See also:
   ///
-  ///  * [standardEasing], the name for this curve in the Material specification.
+  ///  * [Easing.legacy], the name for this curve in the Material specification.
   static const Cubic fastOutSlowIn = Cubic(0.4, 0.0, 0.2, 1.0);
 
   /// A cubic animation curve that starts quickly, slows down, and then ends

packages/flutter/lib/src/material/curves.dart

@@ -6,6 +6,8 @@ import 'package:flutter/animation.dart';
 
 // The easing curves of the Material Library
 
+// TODO(guidezpl): deprecate the three curves below once customers (packages/plugins) are migrated
+
 /// The standard easing curve in the Material specification.
 ///
 /// Elements that begin and end at rest use standard easing.