Add TweenSequenceEffect + test

lib/effects/effects.dart

@@ -19,3 +19,4 @@ export 'then_effect.dart';
 export 'tint_effect.dart';
 export 'toggle_effect.dart';
 export 'visibility_effect.dart';
+export 'tween_sequence_effect.dart';

lib/effects/tween_sequence_effect.dart

@@ -0,0 +1,64 @@
+import 'package:flutter/widgets.dart';
+
+import '../flutter_animate.dart';
+
+/// Provide an easy way to use Flutters TweenSequence API to express
+/// complex multi-part tweens.
+/// ```
+/// // fades in, out, and back in
+/// foo.animate().tweenSequence(
+//   duration: 1.seconds,
+//   sequence: TweenSequence<double>([
+//     TweenSequenceItem(tween: Tween(begin: 0, end: 1), weight: .5),
+//     TweenSequenceItem(tween: Tween(begin: 1, end: 0), weight: .5),
+//     TweenSequenceItem(tween: Tween(begin: 0, end: 1), weight: .5),
+//   ]),
+//   builder: (_, double value, Widget child) {
+//     return Opacity(opacity: value, child: child);
+//   },
+// )
+/// ```
+@immutable
+class TweenSequenceEffect extends Effect<double> {
+  const TweenSequenceEffect(
+      {required this.builder, required this.sequence, Duration? delay, Duration? duration, Curve? curve})
+      : super(delay: delay, duration: duration, curve: curve, begin: 0.0, end: 1.0);
+
+  final TweenSequenceEffectBuilder builder;
+  final TweenSequence sequence;
+
+  @override
+  Widget build(
+    BuildContext context,
+    Widget child,
+    AnimationController controller,
+    EffectEntry entry,
+  ) {
+    Animation<double> animation = buildAnimation(controller, entry);
+    return getOptimizedBuilder<double>(
+      animation: animation,
+      builder: (ctx, __) => builder(ctx, sequence.evaluate(animation), child),
+    );
+  }
+}
+
+extension TweenSequenceExtensions<T> on AnimateManager<T> {
+  /// Adds a [custom] extension to [AnimateManager] ([Animate] and [AnimateList]).
+  T tweenSequence({
+    required TweenSequenceEffectBuilder builder,
+    required TweenSequence sequence,
+    Duration? delay,
+    Duration? duration,
+    Curve? curve,
+    double? begin,
+    double? end,
+  }) =>
+      addEffect(
+          TweenSequenceEffect(builder: builder, delay: delay, duration: duration, curve: curve, sequence: sequence));
+}
+
+typedef TweenSequenceEffectBuilder = Widget Function(
+  BuildContext context,
+  double value,
+  Widget child,
+);

pubspec.lock

@@ -60,13 +60,6 @@ packages:
     description: flutter
     source: sdk
     version: "0.0.0"
-  js:
-    dependency: transitive
-    description:
-      name: js
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "0.6.4"
   lints:
     dependency: transitive
     description:
@@ -148,14 +141,14 @@ packages:
       name: test_api
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.4.14"
+    version: "0.4.12"
   vector_math:
     dependency: transitive
     description:
       name: vector_math
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.1.3"
+    version: "2.1.2"
 sdks:
-  dart: ">=2.18.0 <3.0.0"
+  dart: ">=2.17.0-206.0.dev <3.0.0"
   flutter: ">=1.17.0"

test/effects/tween_sequence_test.dart

@@ -0,0 +1,33 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:flutter_animate/flutter_animate.dart';
+
+import '../tester_extensions.dart';
+
+void main() {
+  testWidgets('fade in, out, in ', (tester) async {
+    final animation = const FlutterLogo().animate().tweenSequence(
+          duration: 1.5.seconds,
+          sequence: TweenSequence<double>([
+            TweenSequenceItem(tween: Tween(begin: 0, end: 1), weight: .5),
+            TweenSequenceItem(tween: Tween(begin: 1, end: 0), weight: .5),
+            TweenSequenceItem(tween: Tween(begin: 0, end: 1), weight: .5),
+          ]),
+          builder: (_, double value, Widget child) {
+            return Opacity(opacity: value, child: child);
+          },
+        );
+    // check start
+    await tester.pumpAnimation(animation);
+    tester.expectWidgetWithDouble<Opacity>((ft) => ft.opacity, 0, 'opacity');
+    // check 1/3
+    await tester.pump(500.ms);
+    tester.expectWidgetWithDouble<Opacity>((ft) => ft.opacity, 1, 'opacity');
+    // check 2/3
+    await tester.pump(500.ms);
+    tester.expectWidgetWithDouble<Opacity>((ft) => ft.opacity, 0, 'opacity');
+    // check end
+    await tester.pump(500.ms);
+    tester.expectWidgetWithDouble<Opacity>((ft) => ft.opacity, 1, 'opacity');
+  });
+}