add

2026-10-15 20:36:59 +08:00
commit 6bf949949c
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+import 'dart:async';
+
+import 'package:media_kit/media_kit.dart';
+import 'package:media_kit_video/media_kit_video.dart';
+
+/// 一个播放槽位：Player + 视图控制器 + 当前绑定的视频
+class PlayerSlot {
+  PlayerSlot(this.player);
+
+  final Player player;
+  late final VideoController controller = VideoController(player);
+
+  /// 当前槽位绑定的 videoId（-1 表示空槽）
+  int videoId = -1;
+
+  /// 是否已回调过 complete（每视频每次绑定只触发一次）
+  bool completeNotified = false;
+}
+
+/// Feed 播放器池：3 槽位循环复用，防止 PageView 无限列表下 OOM。
+///
+/// 策略：
+/// - 窗口 [current-1, current, current+1] 映射到 index % 3 槽位
+/// - 当前槽 play，相邻槽仅 open 预缓冲，出窗槽 stop 复位
+/// - 每个槽位独立订阅进度流：position ≥ duration×95% 或 completed → 回调一次 complete
+///
+/// 构造接受 [playerFactory] 便于测试注入 fake（本机无播放器环境）。
+class FeedPlayerPool {
+  FeedPlayerPool({
+    Player Function()? playerFactory,
+    this.onWatchComplete,
+  }) : _playerFactory = playerFactory;
+
+  final Player Function()? _playerFactory;
+
+  /// 完整观看回调：(videoId, watchDuration秒)，由上层做去重与上报
+  final void Function(int videoId, int watchDurationSeconds)? onWatchComplete;
+
+  static const int slotCount = 3;
+
+  final List<PlayerSlot> _slots = [];
+  final List<StreamSubscription> _subs = [];
+
+  int _currentIndex = 0;
+  int get currentIndex => _currentIndex;
+
+  /// 初始化（创建 3 槽位并订阅各自进度流）
+  void init() {
+    for (var i = 0; i < slotCount; i++) {
+      final player = _playerFactory?.call() ?? Player();
+      final slot = PlayerSlot(player);
+      _slots.add(slot);
+      _hookSlot(slot);
+    }
+  }
+
+  /// 槽位号（PageView 页用 index % 3 取对应 controller 渲染）
+  int slotOf(int index) => index % slotCount;
+
+  PlayerSlot slotAt(int slotIndex) => _slots[slotIndex];
+  VideoController controllerAt(int slotIndex) => _slots[slotIndex].controller;
+
+  PlayerSlot get currentSlot => _slots[slotOf(_currentIndex)];
+
+  bool get isCurrentPlaying => currentSlot.player.state.playing;
+
+  /// 绑定窗口：index 为当前页；items 为已解析好播放地址的窗口数据源
+  void bindWindow(int index, List<({int videoId, String url})> items) {
+    _currentIndex = index;
+    // 1. 窗口内槽位按需加载
+    for (var offset = -1; offset <= 1; offset++) {
+      final i = index + offset;
+      if (i < 0 || i >= items.length) continue;
+      final slot = _slots[slotOf(i)];
+      final item = items[i];
+      if (slot.videoId == item.videoId) continue; // 已加载，避免重复 open
+      slot.videoId = item.videoId;
+      slot.completeNotified = false;
+      if (item.url.isNotEmpty) {
+        slot.player.open(Media(item.url), play: false);
+      }
+    }
+    // 2. 槽位状态：当前播、相邻预缓冲（保持 pause）、出窗复位
+    for (var s = 0; s < slotCount; s++) {
+      final slot = _slots[s];
+      if (s == slotOf(index)) continue;
+      if (slot.videoId == -1) continue;
+      if (_inWindow(slot.videoId, index, items)) {
+        slot.player.pause(); // 窗口内非当前：预缓冲不播放
+      } else {
+        slot.player.stop();
+        slot.videoId = -1; // 出窗复位
+      }
+    }
+    currentSlot.player.play();
+  }
+
+  bool _inWindow(int videoId, int index, List<({int videoId, String url})> items) {
+    for (var offset = -1; offset <= 1; offset++) {
+      final i = index + offset;
+      if (i >= 0 && i < items.length && items[i].videoId == videoId) return true;
+    }
+    return false;
+  }
+
+  /// 每槽位独立订阅：≥95% 或播完触发一次 complete 回调
+  void _hookSlot(PlayerSlot slot) {
+    var lastPosition = Duration.zero;
+    _subs.add(slot.player.stream.position.listen((pos) {
+      lastPosition = pos;
+      if (slot.videoId < 0 || slot.completeNotified) return;
+      // 仅当前槽才上报（预缓冲槽不应触发）
+      if (slot != currentSlot) return;
+      final dur = slot.player.state.duration;
+      if (dur.inMilliseconds > 0 &&
+          pos.inMilliseconds >= dur.inMilliseconds * 0.95) {
+        slot.completeNotified = true;
+        onWatchComplete?.call(slot.videoId, pos.inSeconds);
+      }
+    }));
+    _subs.add(slot.player.stream.completed.listen((done) {
+      if (!done) return;
+      if (slot.videoId < 0 || slot.completeNotified) return;
+      if (slot != currentSlot) return;
+      slot.completeNotified = true;
+      onWatchComplete?.call(slot.videoId, lastPosition.inSeconds);
+    }));
+  }
+
+  /// 暂停/继续/切换当前槽（手势与生命周期用）
+  void pauseCurrent() => currentSlot.player.pause();
+  void playCurrent() => currentSlot.player.play();
+  void toggleCurrent() => currentSlot.player.playOrPause();
+
+  /// 释放全部资源（Feed 页 dispose 时调用）
+  Future<void> dispose() async {
+    for (final sub in _subs) {
+      await sub.cancel();
+    }
+    _subs.clear();
+    for (final slot in _slots) {
+      await slot.player.dispose();
+    }
+  }
+}