正在播放的自滑动刹车动画动作优化完成，同时调整播放页进入动作

lib/pages/playlist_page.dart

@@ -14,12 +14,17 @@ class _PlaylistPageState extends State<PlaylistPage> {
   final ScrollController _scrollController = ScrollController();
   final GlobalKey _currentTagKey = GlobalKey();
 
-  // ⭐ 定位事务 ID（防止旧任务污染）
   int _scrollGeneration = 0;
-
-  // ⭐ 是否已完成定位
   bool _hasScrolledToCurrent = false;
 
+  // ⭐ 固定 item 高度（根据实际 ListTile 测量结果调整）
+  // 实际约 72-76px，取 74px 作为稳定值
+  static const double _itemExtent = 74.0;
+
+  // 舒适区范围
+  static const double _comfortZoneTop = 0.15;
+  static const double _comfortZoneBottom = 0.85;
+
   @override
   void initState() {
     super.initState();
@@ -34,7 +39,18 @@ class _PlaylistPageState extends State<PlaylistPage> {
     super.dispose();
   }
 
-  /// ⭐ 核心：一次计算 + 一次动画
+  bool _isItemInComfortZone(
+      RenderBox renderBox, double viewportHeight, double listTop) {
+    final itemGlobal = renderBox.localToGlobal(Offset.zero);
+    final itemTop = itemGlobal.dy - listTop;
+    final itemBottom = itemTop + renderBox.size.height;
+
+    final topBoundary = viewportHeight * _comfortZoneTop;
+    final bottomBoundary = viewportHeight * _comfortZoneBottom;
+
+    return itemTop >= topBoundary && itemBottom <= bottomBoundary;
+  }
+
   Future<void> _scrollToCurrentSong() async {
     if (_hasScrolledToCurrent) return;
 
@@ -46,42 +62,59 @@ class _PlaylistPageState extends State<PlaylistPage> {
       return;
     }
 
-    // 生成新的事务 ID，使旧任务失效
     final generation = ++_scrollGeneration;
 
-    // 等待页面稳定
-    await Future.delayed(const Duration(milliseconds: 300));
+    // ⭐ 等待两帧，确保 ListView 完全稳定
+    await WidgetsBinding.instance.endOfFrame;
+    await WidgetsBinding.instance.endOfFrame;
     if (!mounted || generation != _scrollGeneration) return;
 
-    // 获取目标 item 的当前布局状态
+    // ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+    // 第一阶段：检测当前歌曲是否已经在舒适区内
+    // ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
     var tagContext = _currentTagKey.currentContext;
 
-    // ⭐ 如果 Tag 还没被构建，用不可见的 jumpTo 触发布局
+    if (tagContext != null) {
+      final renderBox = tagContext.findRenderObject() as RenderBox?;
+      if (renderBox != null) {
+        final viewportHeight = _scrollController.position.viewportDimension;
+        final listRenderBox = context.findRenderObject() as RenderBox?;
+        if (listRenderBox != null) {
+          final listTop = listRenderBox.localToGlobal(Offset.zero).dy;
+          if (_isItemInComfortZone(renderBox, viewportHeight, listTop)) {
+            debugPrint('🎯 [定位] 当前歌曲已在舒适区内，不滚动');
+            _hasScrolledToCurrent = true;
+            return;
+          }
+        }
+      }
+    }
+
+    // ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+    // 第二阶段：粗定位（使用固定 itemExtent，不再依赖 maxExtent）
+    // ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
     if (tagContext == null) {
-      // 用 maxExtent 计算平均高度，做一次瞬时定位
-      final maxExtent = _scrollController.position.maxScrollExtent;
-      final avgHeight = maxExtent / queue.length;
       final viewportHeight = _scrollController.position.viewportDimension;
-      final roughOffset =
-          (currentIndex * avgHeight) - (viewportHeight / 2) + (avgHeight / 2);
+      // ⭐ 固定高度计算，无需读取 maxExtent，更稳定更快
+      final roughOffset = (currentIndex * _itemExtent) - (viewportHeight * 0.3);
+      final maxExtent = _scrollController.position.maxScrollExtent;
       final clamped = roughOffset.clamp(0.0, maxExtent);
 
-      // ⭐ 瞬时跳转（用户不可见）
+      // ⭐ 不可见瞬时跳转
       _scrollController.jumpTo(clamped);
 
-      // 等待一帧，让目标 item 被构建
+      // 等待目标被构建（只需要一帧，因为高度固定，布局更快）
       await WidgetsBinding.instance.endOfFrame;
       if (!mounted || generation != _scrollGeneration) return;
 
       tagContext = _currentTagKey.currentContext;
 
-      // 如果还是 null，说明估算偏差太大，用迭代方式推进
+      // 如果还是 null，用迭代方式推进（但固定高度下很少需要）
       if (tagContext == null) {
-        // 最多尝试 2 次，每次推进半屏
         for (int i = 0; i < 2; i++) {
           final viewportHeight2 = _scrollController.position.viewportDimension;
           final direction = (currentIndex > queue.length / 2) ? -1 : 1;
-          final step = viewportHeight2 * 0.7 * direction;
+          final step = viewportHeight2 * 0.5 * direction;
           final newOffset = (_scrollController.offset + step)
               .clamp(0.0, _scrollController.position.maxScrollExtent);
           _scrollController.jumpTo(newOffset);
@@ -99,43 +132,51 @@ class _PlaylistPageState extends State<PlaylistPage> {
 
     if (!mounted || generation != _scrollGeneration) return;
 
-    // ⭐ 获取 Tag 的真实位置
+    // ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+    // 第三阶段：精确定位到舒适区
+    // ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
     final renderBox = tagContext!.findRenderObject() as RenderBox?;
     if (renderBox == null) {
       _hasScrolledToCurrent = true;
       return;
     }
 
-    final tagPosition = renderBox.localToGlobal(Offset.zero);
-    final tagSize = renderBox.size;
-    final tagCenter = tagPosition.dy + tagSize.height / 2;
-
-    final screenHeight = MediaQuery.of(context).size.height;
-    final screenCenter = screenHeight / 2;
-
-    final delta = tagCenter - screenCenter;
-    final currentOffset = _scrollController.offset;
-    final targetOffset = (currentOffset + delta)
-        .clamp(0.0, _scrollController.position.maxScrollExtent);
-
-    // 如果偏差太小，直接标记完成
-    if ((targetOffset - currentOffset).abs() < 5) {
+    final listRenderBox = context.findRenderObject() as RenderBox?;
+    if (listRenderBox == null) {
       _hasScrolledToCurrent = true;
       return;
     }
 
-    // ⭐ 根据距离动态计算时长
+    final itemGlobal = renderBox.localToGlobal(Offset.zero);
+    final listTop = listRenderBox.localToGlobal(Offset.zero).dy;
+    final viewportHeight = _scrollController.position.viewportDimension;
+    final itemHeight = renderBox.size.height;
+
+    final targetTop = viewportHeight * _comfortZoneTop;
+    final relativeOffset = itemGlobal.dy - listTop;
+    final currentOffset = _scrollController.offset;
+    final targetOffset = (currentOffset + relativeOffset - targetTop)
+        .clamp(0.0, _scrollController.position.maxScrollExtent);
+
     final distance = (targetOffset - currentOffset).abs();
-    final durationMs = (250 + distance * 0.3).clamp(250, 700).round();
-    final duration = Duration(milliseconds: durationMs);
+
+    if (distance < 5) {
+      _hasScrolledToCurrent = true;
+      return;
+    }
+
+    final isFirstEntry = _scrollController.offset == 0 && currentIndex > 5;
+    final durationMs = isFirstEntry
+        ? (150 + distance * 0.12).clamp(150, 350).round()
+        : (200 + distance * 0.15).clamp(200, 500).round();
 
     debugPrint(
-        '🎯 [定位] 距离: ${distance.toStringAsFixed(0)}px, 时长: ${durationMs}ms');
+        '🎯 [定位] 偏移: ${currentOffset.toStringAsFixed(0)} → ${targetOffset.toStringAsFixed(0)}, '
+        '距离: ${distance.toStringAsFixed(0)}px, 时长: ${durationMs}ms');
 
-    // ⭐ 唯一的一次可见动画
     await _scrollController.animateTo(
       targetOffset,
-      duration: duration,
+      duration: Duration(milliseconds: durationMs),
       curve: Curves.easeOutCubic,
     );
 
@@ -218,6 +259,8 @@ class _PlaylistPageState extends State<PlaylistPage> {
           : ListView.builder(
               controller: _scrollController,
               padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
+              // ⭐ 关键优化：固定 item 高度
+              itemExtent: _itemExtent,
               itemCount: queue.length,
               itemBuilder: (context, index) {
                 final song = queue[index];