287 lines
9.8 KiB
Dart
287 lines
9.8 KiB
Dart
// lib/pages/playlist_page.dart
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import 'package:flutter/material.dart';
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import 'package:provider/provider.dart';
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import '../services/audio_service.dart';
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class PlaylistPage extends StatefulWidget {
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const PlaylistPage({super.key});
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@override
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State<PlaylistPage> createState() => _PlaylistPageState();
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}
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class _PlaylistPageState extends State<PlaylistPage> {
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final ScrollController _scrollController = ScrollController();
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final GlobalKey _currentTagKey = GlobalKey();
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// ⭐ 定位事务 ID（防止旧任务污染）
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int _scrollGeneration = 0;
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// ⭐ 是否已完成定位
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bool _hasScrolledToCurrent = false;
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@override
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void initState() {
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super.initState();
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WidgetsBinding.instance.addPostFrameCallback((_) {
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_scrollToCurrentSong();
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});
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}
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@override
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void dispose() {
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_scrollController.dispose();
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super.dispose();
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}
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/// ⭐ 核心：一次计算 + 一次动画
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Future<void> _scrollToCurrentSong() async {
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if (_hasScrolledToCurrent) return;
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final service = context.read<AudioService>();
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final queue = service.queue;
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final currentIndex = service.currentIndex;
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if (queue.isEmpty || currentIndex < 0 || currentIndex >= queue.length) {
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return;
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}
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// 生成新的事务 ID，使旧任务失效
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final generation = ++_scrollGeneration;
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// 等待页面稳定
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await Future.delayed(const Duration(milliseconds: 300));
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if (!mounted || generation != _scrollGeneration) return;
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// 获取目标 item 的当前布局状态
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var tagContext = _currentTagKey.currentContext;
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// ⭐ 如果 Tag 还没被构建，用不可见的 jumpTo 触发布局
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if (tagContext == null) {
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// 用 maxExtent 计算平均高度，做一次瞬时定位
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final maxExtent = _scrollController.position.maxScrollExtent;
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final avgHeight = maxExtent / queue.length;
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final viewportHeight = _scrollController.position.viewportDimension;
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final roughOffset =
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(currentIndex * avgHeight) - (viewportHeight / 2) + (avgHeight / 2);
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final clamped = roughOffset.clamp(0.0, maxExtent);
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// ⭐ 瞬时跳转（用户不可见）
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_scrollController.jumpTo(clamped);
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// 等待一帧，让目标 item 被构建
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await WidgetsBinding.instance.endOfFrame;
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if (!mounted || generation != _scrollGeneration) return;
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tagContext = _currentTagKey.currentContext;
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// 如果还是 null，说明估算偏差太大，用迭代方式推进
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if (tagContext == null) {
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// 最多尝试 2 次，每次推进半屏
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for (int i = 0; i < 2; i++) {
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final viewportHeight2 = _scrollController.position.viewportDimension;
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final direction = (currentIndex > queue.length / 2) ? -1 : 1;
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final step = viewportHeight2 * 0.7 * direction;
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final newOffset = (_scrollController.offset + step)
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.clamp(0.0, _scrollController.position.maxScrollExtent);
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_scrollController.jumpTo(newOffset);
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await WidgetsBinding.instance.endOfFrame;
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if (!mounted || generation != _scrollGeneration) return;
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tagContext = _currentTagKey.currentContext;
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if (tagContext != null) break;
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}
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if (tagContext == null) {
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_hasScrolledToCurrent = true;
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return;
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}
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}
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}
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if (!mounted || generation != _scrollGeneration) return;
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// ⭐ 获取 Tag 的真实位置
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final renderBox = tagContext!.findRenderObject() as RenderBox?;
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if (renderBox == null) {
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_hasScrolledToCurrent = true;
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return;
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}
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final tagPosition = renderBox.localToGlobal(Offset.zero);
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final tagSize = renderBox.size;
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final tagCenter = tagPosition.dy + tagSize.height / 2;
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final screenHeight = MediaQuery.of(context).size.height;
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final screenCenter = screenHeight / 2;
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final delta = tagCenter - screenCenter;
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final currentOffset = _scrollController.offset;
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final targetOffset = (currentOffset + delta)
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.clamp(0.0, _scrollController.position.maxScrollExtent);
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// 如果偏差太小，直接标记完成
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if ((targetOffset - currentOffset).abs() < 5) {
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_hasScrolledToCurrent = true;
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return;
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}
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// ⭐ 根据距离动态计算时长
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final distance = (targetOffset - currentOffset).abs();
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final durationMs = (250 + distance * 0.3).clamp(250, 700).round();
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final duration = Duration(milliseconds: durationMs);
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debugPrint(
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'🎯 [定位] 距离: ${distance.toStringAsFixed(0)}px, 时长: ${durationMs}ms');
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// ⭐ 唯一的一次可见动画
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await _scrollController.animateTo(
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targetOffset,
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duration: duration,
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curve: Curves.easeOutCubic,
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);
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if (mounted && generation == _scrollGeneration) {
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_hasScrolledToCurrent = true;
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}
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}
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@override
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Widget build(BuildContext context) {
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final service = context.watch<AudioService>();
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final queue = service.queue;
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final currentIndex = service.currentIndex;
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return Scaffold(
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backgroundColor: const Color(0xFF0E1211),
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appBar: AppBar(
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title: const Text(
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'播放列表',
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style: TextStyle(
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color: Colors.white,
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fontSize: 18,
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fontWeight: FontWeight.w500,
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),
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),
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backgroundColor: Colors.transparent,
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elevation: 0,
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foregroundColor: Colors.white,
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leading: IconButton(
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icon: const Icon(Icons.arrow_back_ios_new),
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onPressed: () => Navigator.pop(context),
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),
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actions: [
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IconButton(
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icon: Icon(service.playModeIcon, color: Colors.white54),
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onPressed: service.togglePlayMode,
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),
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IconButton(
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icon: const Icon(Icons.clear_all, color: Colors.white54),
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onPressed: () {
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showDialog(
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context: context,
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builder: (context) => AlertDialog(
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backgroundColor: const Color(0xFF1A1F1E),
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title: const Text('清空播放列表',
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style: TextStyle(color: Colors.white)),
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content: const Text('确定要清空当前播放列表吗？',
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style: TextStyle(color: Colors.grey)),
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actions: [
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TextButton(
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onPressed: () => Navigator.pop(context),
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child: const Text('取消')),
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TextButton(
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onPressed: () {
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service.clearQueue();
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Navigator.pop(context);
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Navigator.pop(context);
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},
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child:
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const Text('清空', style: TextStyle(color: Colors.red)),
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),
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],
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),
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);
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},
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),
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],
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),
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body: queue.isEmpty
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? const Center(
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child: Column(
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mainAxisAlignment: MainAxisAlignment.center,
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children: [
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Icon(Icons.playlist_play, size: 48, color: Colors.grey),
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SizedBox(height: 16),
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Text('播放列表为空', style: TextStyle(color: Colors.grey)),
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],
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),
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)
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: ListView.builder(
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controller: _scrollController,
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padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
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itemCount: queue.length,
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itemBuilder: (context, index) {
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final song = queue[index];
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final isCurrent = index == currentIndex;
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return ListTile(
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contentPadding: const EdgeInsets.symmetric(
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horizontal: 8,
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vertical: 4,
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),
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leading: Icon(
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isCurrent ? Icons.play_arrow : Icons.music_note,
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color:
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isCurrent ? const Color(0xFFB8D4D0) : Colors.grey[600],
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size: 24,
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),
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title: Text(
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song.title,
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style: TextStyle(
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fontSize: 16,
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fontWeight: isCurrent ? FontWeight.w600 : FontWeight.w400,
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color: isCurrent ? Colors.white : Colors.grey[300],
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),
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maxLines: 1,
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overflow: TextOverflow.ellipsis,
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),
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subtitle: Text(
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song.artist,
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style: TextStyle(
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fontSize: 13,
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color: isCurrent ? Colors.grey[400] : Colors.grey[600],
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),
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maxLines: 1,
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overflow: TextOverflow.ellipsis,
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),
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trailing: isCurrent
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? Container(
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key: _currentTagKey,
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padding: const EdgeInsets.symmetric(
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horizontal: 8,
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vertical: 2,
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),
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decoration: BoxDecoration(
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color:
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const Color(0xFFB8D4D0).withValues(alpha: 0.2),
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borderRadius: BorderRadius.circular(4),
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),
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child: const Text(
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'正在播放',
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style: TextStyle(
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fontSize: 10,
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color: Color(0xFFB8D4D0),
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),
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),
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)
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: null,
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onTap: () {
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service.setQueue(queue, startIndex: index);
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Navigator.pop(context);
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},
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);
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},
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),
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);
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}
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}
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