fix(player): 修正缓冲态与首帧时间闪现

lib/pages/player/widgets/seek_progress_bar.dart

@@ -43,6 +43,7 @@ class SeekProgressBar extends StatefulWidget {
     this.episodeId,
     this.thumbnailsUrl,
     this.fallbackDuration = Duration.zero,
+    this.suppressBufferLoading = false,
   });
 
   final ValueListenable<VideoPlayerValue>? valueListenable;
@@ -59,6 +60,7 @@ class SeekProgressBar extends StatefulWidget {
   final String? episodeId;
   final String? thumbnailsUrl;
   final Duration fallbackDuration;
+  final bool suppressBufferLoading;
 
   @override
   State<SeekProgressBar> createState() => _SeekProgressBarState();
@@ -74,6 +76,7 @@ class _SeekProgressBarState extends State<SeekProgressBar> {
   bool _pointerMoved = false;
   Offset? _pointerStart;
   double? _dragStartFraction;
+  Duration? _lastPosition;
 
   @override
   void initState() {
@@ -90,13 +93,22 @@ class _SeekProgressBarState extends State<SeekProgressBar> {
       _bufferTimer?.cancel();
       _bufferTimer = null;
       _buffering = false;
+      _lastPosition = null;
       widget.thumbnailService?.cancelPending();
       _attachSource();
     }
+    if (oldWidget.suppressBufferLoading != widget.suppressBufferLoading) {
+      _bufferTimer?.cancel();
+      _bufferTimer = null;
+      _lastPosition = null;
+      _buffering = false;
+      _syncBufferState(notify: false);
+    }
     if (oldWidget.locked != widget.locked) {
       _bufferTimer?.cancel();
       _bufferTimer = null;
       _buffering = false;
+      _lastPosition = null;
       if (widget.locked) {
         widget.thumbnailService?.cancelPending();
         _previewFraction.value = null;
@@ -130,14 +142,24 @@ class _SeekProgressBarState extends State<SeekProgressBar> {
 
   void _syncBufferState({bool notify = true}) {
     final source = widget.valueListenable;
-    if (widget.locked || source == null) {
+    if (widget.locked || widget.suppressBufferLoading || source == null) {
       _bufferTimer?.cancel();
       _bufferTimer = null;
+      _lastPosition = null;
       _setBuffering(false, notify: notify);
       return;
     }
     final value = source.value;
     if (!value.isInitialized) {
+      _bufferTimer?.cancel();
+      _bufferTimer = null;
+      _lastPosition = null;
+      _setBuffering(false, notify: notify);
+      return;
+    }
+    final previousPosition = _lastPosition;
+    _lastPosition = value.position;
+    if (previousPosition != null && value.position > previousPosition) {
       _bufferTimer?.cancel();
       _bufferTimer = null;
       _setBuffering(false, notify: notify);
@@ -149,14 +171,24 @@ class _SeekProgressBarState extends State<SeekProgressBar> {
       _setBuffering(false, notify: notify);
       return;
     }
+    // 首次看到“已播放且有画面”的 buffering 状态时，以 position 为基线，
+    // 不抢先显示 loading；后续 position 停滞超过阈值才视为真实卡顿。
+    if (previousPosition == null &&
+        value.isPlaying &&
+        value.position > Duration.zero) {
+      _setBuffering(false, notify: notify);
+      return;
+    }
     if (_buffering || _bufferTimer != null) return;
+    final bufferingPosition = value.position;
     _bufferTimer = Timer(_bufferDebounce, () {
       _bufferTimer = null;
       final current = widget.valueListenable;
       if (!mounted ||
           current != source ||
           !current!.value.isInitialized ||
-          !current.value.isBuffering) {
+          !current.value.isBuffering ||
+          current.value.position != bufferingPosition) {
         return;
       }
       _setBuffering(true);
@@ -227,7 +259,11 @@ class _SeekProgressBarState extends State<SeekProgressBar> {
         : widget.fallbackDuration;
     final total = duration.inMilliseconds;
     final scrubbing = _dragging;
-    final loading = !widget.locked && !scrubbing && _buffering;
+    final loading =
+        !widget.locked &&
+        !widget.suppressBufferLoading &&
+        !scrubbing &&
+        _buffering;
     final enabled =
         !widget.locked &&
         video.isInitialized &&
@@ -243,6 +279,8 @@ class _SeekProgressBarState extends State<SeekProgressBar> {
     final showPreview =
         scrubbing &&
         widget.showTimes &&
+        video.isInitialized &&
+        total > 0 &&
         widget.thumbnailService != null &&
         (widget.episodeId?.isNotEmpty ?? false);
     final trackHeight = scrubbing ? 6.0 : 2.0;
@@ -253,21 +291,6 @@ class _SeekProgressBarState extends State<SeekProgressBar> {
         final track = Column(
           mainAxisSize: MainAxisSize.min,
           children: [
-            if (widget.showTimes && !video.isInitialized)
-              Padding(
-                padding: const EdgeInsets.only(bottom: 2),
-                child: Text(
-                  '00:00 / ${_format(duration)}',
-                  key: const Key('player-progress-uninitialized-time'),
-                  textAlign: TextAlign.center,
-                  style: const TextStyle(
-                    color: AppColors.onPrimary,
-                    fontSize: 12,
-                    fontWeight: FontWeight.w600,
-                    height: 1.2,
-                  ),
-                ),
-              ),
             if (widget.showTimes && scrubbing && !showPreview)
               Padding(
                 padding: const EdgeInsets.only(bottom: 2),