feat(player): animate Material seek bar with expressive waves

test/expressive_seek_track_test.dart

@@ -0,0 +1,161 @@
+import 'package:flutter/material.dart';
+import 'package:flutter/semantics.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:spotiflac_android/theme/mornye_theme.dart';
+import 'package:spotiflac_android/widgets/expressive_seek_track.dart';
+import 'package:spotiflac_android/widgets/playback_seek_slider.dart';
+
+Widget _host({
+  bool playing = true,
+  bool reduceMotion = false,
+  bool visible = true,
+  bool mornye = false,
+  TextDirection direction = TextDirection.ltr,
+  Duration position = const Duration(seconds: 30),
+  Duration duration = const Duration(seconds: 100),
+  Future<void> Function(Duration)? onSeek,
+}) => MaterialApp(
+  theme: mornye ? MornyeTheme.build(Brightness.dark) : null,
+  home: MediaQuery(
+    data: MediaQueryData(disableAnimations: reduceMotion),
+    child: Directionality(
+      textDirection: direction,
+      child: TickerMode(
+        enabled: visible,
+        child: Scaffold(
+          body: Center(
+            child: PlaybackSeekSlider(
+              playing: playing,
+              position: position,
+              duration: duration,
+              onSeek: onSeek ?? (_) async {},
+            ),
+          ),
+        ),
+      ),
+    ),
+  ),
+);
+
+ExpressiveSeekTrackShape _track(WidgetTester tester) =>
+    SliderTheme.of(tester.element(find.byType(Slider))).trackShape!
+        as ExpressiveSeekTrackShape;
+
+void main() {
+  testWidgets('wave travels during playback and settles smoothly on pause', (
+    tester,
+  ) async {
+    await tester.pumpWidget(_host());
+    await tester.pump(const Duration(milliseconds: 400));
+    final phase = _track(tester).phase;
+    expect(_track(tester).amplitude, 1);
+    await tester.pump(const Duration(milliseconds: 100));
+    expect(_track(tester).phase, isNot(phase));
+    expect(tester.widget<Slider>(find.byType(Slider)).value, 30000);
+
+    await tester.pumpWidget(_host(playing: false));
+    await tester.pump(const Duration(milliseconds: 150));
+    expect(_track(tester).amplitude, greaterThan(0));
+    expect(_track(tester).amplitude, lessThan(1));
+    await tester.pumpAndSettle();
+    expect(_track(tester).amplitude, 0);
+    final pausedPhase = _track(tester).phase;
+    await tester.pump(const Duration(seconds: 2));
+    expect(_track(tester).phase, pausedPhase);
+    expect(tester.binding.hasScheduledFrame, isFalse);
+
+    await tester.pumpWidget(_host());
+    await tester.pump(const Duration(milliseconds: 400));
+    expect(_track(tester).amplitude, 1);
+    expect(_track(tester).phase, isNot(pausedPhase));
+  });
+
+  testWidgets('scrubbing flattens the track and playback restores the wave', (
+    tester,
+  ) async {
+    final seeks = <Duration>[];
+    await tester.pumpWidget(_host(onSeek: (target) async => seeks.add(target)));
+    await tester.pump(const Duration(milliseconds: 400));
+    final bounds = tester.getRect(find.byType(Slider));
+    final gesture = await tester.startGesture(bounds.center);
+    await gesture.moveBy(Offset(bounds.width * 0.2, 0));
+    await tester.pump();
+    await tester.pump(const Duration(milliseconds: 400));
+    expect(_track(tester).amplitude, 0);
+    expect(seeks, isEmpty);
+    final preview = tester.widget<Slider>(find.byType(Slider)).value;
+    await gesture.up();
+    await tester.pump();
+    await tester.pump(const Duration(milliseconds: 400));
+    expect(seeks, [Duration(milliseconds: preview.round())]);
+    expect(_track(tester).amplitude, 1);
+  });
+
+  testWidgets('reduced motion and hidden routes stop the animation', (
+    tester,
+  ) async {
+    for (final reduceMotion in [true, false]) {
+      await tester.pumpWidget(_host());
+      await tester.pump(const Duration(milliseconds: 400));
+      expect(_track(tester).amplitude, 1);
+      await tester.pumpWidget(
+        _host(reduceMotion: reduceMotion, visible: reduceMotion),
+      );
+      await tester.pumpAndSettle();
+      expect(_track(tester).amplitude, 0);
+      final phase = _track(tester).phase;
+      await tester.pump(const Duration(seconds: 2));
+      expect(_track(tester).phase, phase);
+      expect(tester.binding.hasScheduledFrame, isFalse);
+    }
+  });
+
+  testWidgets('unknown and completed tracks do not animate', (tester) async {
+    for (final duration in [Duration.zero, const Duration(seconds: 30)]) {
+      await tester.pumpWidget(_host(duration: duration));
+      await tester.pumpAndSettle();
+      expect(_track(tester).amplitude, 0);
+      expect(tester.binding.hasScheduledFrame, isFalse);
+    }
+  });
+
+  testWidgets('Mornye keeps its continuous track without a wave or handle', (
+    tester,
+  ) async {
+    await tester.pumpWidget(_host(mornye: true));
+    await tester.pumpAndSettle();
+    expect(find.byType(ExpressiveSeekTrack), findsNothing);
+    final theme = SliderTheme.of(tester.element(find.byType(Slider)));
+    expect(theme.trackShape, isA<RoundedRectSliderTrackShape>());
+    expect(theme.thumbShape, SliderComponentShape.noThumb);
+    expect(tester.binding.hasScheduledFrame, isFalse);
+  });
+
+  testWidgets('RTL seeking and screen reader adjustment remain available', (
+    tester,
+  ) async {
+    final semantics = tester.ensureSemantics();
+    final seeks = <Duration>[];
+    await tester.pumpWidget(
+      _host(
+        direction: TextDirection.rtl,
+        onSeek: (target) async => seeks.add(target),
+      ),
+    );
+    final bounds = tester.getRect(find.byType(Slider));
+    await tester.tapAt(
+      Offset(bounds.left + bounds.width * 0.2, bounds.center.dy),
+    );
+    await tester.pump();
+    expect(seeks.single.inSeconds, greaterThan(70));
+    final node = tester.semantics.simulatedAccessibilityTraversal().singleWhere(
+      (node) => node.getSemanticsData().flagsCollection.isSlider,
+    );
+    expect(node.getSemanticsData().hasAction(SemanticsAction.increase), isTrue);
+    node.owner!.performAction(node.id, SemanticsAction.increase);
+    await tester.pump();
+    expect(seeks, hasLength(2));
+    expect(seeks.last.inSeconds, greaterThan(30));
+    semantics.dispose();
+  });
+}

test/now_playing_lyrics_transition_test.dart

@@ -24,6 +24,7 @@ import 'package:spotiflac_android/screens/now_playing_screen.dart';
 import 'package:spotiflac_android/theme/mornye_theme.dart';
 import 'package:spotiflac_android/theme/app_theme.dart';
 import 'package:spotiflac_android/widgets/expressive_icon_button.dart';
+import 'package:spotiflac_android/widgets/expressive_seek_track.dart';
 import 'package:spotiflac_android/widgets/mornye_volume_control.dart';
 import 'package:spotiflac_android/widgets/lyric_gap_indicator.dart';
 import 'package:spotiflac_android/widgets/mornye_player_queue.dart';
@@ -187,6 +188,42 @@ void main() {
     );
   }
 
+  testWidgets('Material seek wave follows playback, buffering and pause', (
+    tester,
+  ) async {
+    final playback = StreamController<PlaybackState>.broadcast();
+    addTearDown(playback.close);
+    await pumpNowPlaying(tester, playbackEvents: playback.stream);
+    mediaItems.add(item('first'));
+    await tester.pumpAndSettle();
+
+    for (final state in [
+      PlaybackState(playing: true, processingState: AudioProcessingState.ready),
+      PlaybackState(
+        playing: true,
+        processingState: AudioProcessingState.buffering,
+      ),
+      PlaybackState(playing: true, processingState: AudioProcessingState.ready),
+      PlaybackState(
+        playing: false,
+        processingState: AudioProcessingState.ready,
+      ),
+    ]) {
+      playback.add(state);
+      await tester.pump();
+      await tester.pump(const Duration(milliseconds: 400));
+      final track = tester.widget<ExpressiveSeekTrack>(
+        find.byType(ExpressiveSeekTrack),
+      );
+      expect(
+        track.playing,
+        state.playing && state.processingState == AudioProcessingState.ready,
+      );
+    }
+    await tester.pumpAndSettle();
+    expect(tester.takeException(), isNull);
+  });
+
   for (final page in ['player', 'lyrics', 'queue']) {
     testWidgets('cover swipe changes the track in the Mornye $page', (
       tester,

test/playback_seek_slider_test.dart

@@ -18,6 +18,7 @@ void main() {
       home: Scaffold(
         body: PlaybackSeekSlider(
           preview: sharedPreview,
+          playing: true,
           position: position,
           duration: const Duration(seconds: 100),
           onSeek: (target) {