fix(player): 持久化竖滑播放画面层

lib/pages/player/widgets/player_render_stack.dart

@@ -0,0 +1,203 @@
+// Author: fruit.com.cn
+
+import 'package:flutter/foundation.dart';
+import 'package:flutter/material.dart';
+import 'package:video_player/video_player.dart';
+
+import '../../../core/theme/app_colors.dart';
+import 'player_opening_frame.dart';
+import 'player_video_surface.dart';
+
+enum PlayerRenderSlotRole { previous, current, next }
+
+class PlayerRenderSlotData {
+  const PlayerRenderSlotData({
+    required this.role,
+    this.index,
+    this.pagePosition,
+    this.controller,
+    this.videoUrl = '',
+    this.theater = false,
+    this.placeholder,
+    this.warmFrameAvailable = false,
+    this.thumbnailReady = false,
+    this.posterReady = false,
+    this.fallback = PlayerOpeningFallback.black,
+    this.warmSlotReused = false,
+    this.waitForPlaybackFrame = false,
+  });
+
+  final PlayerRenderSlotRole role;
+  final int? index;
+  final double? pagePosition;
+  final VideoPlayerController? controller;
+  final String videoUrl;
+  final bool theater;
+  final Widget? placeholder;
+  final bool warmFrameAvailable;
+  final bool thumbnailReady;
+  final bool posterReady;
+  final PlayerOpeningFallback fallback;
+  final bool warmSlotReused;
+  final bool waitForPlaybackFrame;
+
+  factory PlayerRenderSlotData.empty(PlayerRenderSlotRole role) {
+    return PlayerRenderSlotData(role: role);
+  }
+}
+
+/// 播放画面不随 PageView 生命周期销毁，三个固定槽位只更新控制器和位置。
+class PlayerRenderStack extends StatefulWidget {
+  const PlayerRenderStack({
+    super.key,
+    required this.pageController,
+    required this.slots,
+  });
+
+  final PageController pageController;
+  final Map<PlayerRenderSlotRole, PlayerRenderSlotData> slots;
+
+  @override
+  State<PlayerRenderStack> createState() => _PlayerRenderStackState();
+}
+
+class _PlayerRenderStackState extends State<PlayerRenderStack> {
+  int? _lastCurrentIndex;
+
+  @override
+  void initState() {
+    super.initState();
+    _lastCurrentIndex = _currentSlot.index;
+    _log('init current=${_lastCurrentIndex ?? '-'}');
+  }
+
+  @override
+  void didUpdateWidget(covariant PlayerRenderStack oldWidget) {
+    super.didUpdateWidget(oldWidget);
+    final currentIndex = _currentSlot.index;
+    if (_lastCurrentIndex != currentIndex) {
+      _log(
+        'session-index previous=${_lastCurrentIndex ?? '-'} '
+        'current=${currentIndex ?? '-'}',
+      );
+      _lastCurrentIndex = currentIndex;
+    }
+  }
+
+  @override
+  void dispose() {
+    _log('dispose current=${_lastCurrentIndex ?? '-'}');
+    super.dispose();
+  }
+
+  PlayerRenderSlotData get _currentSlot =>
+      widget.slots[PlayerRenderSlotRole.current] ??
+      PlayerRenderSlotData.empty(PlayerRenderSlotRole.current);
+
+  @override
+  Widget build(BuildContext context) {
+    return IgnorePointer(
+      child: AnimatedBuilder(
+        animation: widget.pageController,
+        builder: (context, _) {
+          return LayoutBuilder(
+            builder: (context, constraints) {
+              final viewportHeight = constraints.maxHeight.isFinite
+                  ? constraints.maxHeight
+                  : MediaQuery.sizeOf(context).height;
+              final pageOffset = _pageOffset();
+              final currentPage = _currentSlot.pagePosition ?? pageOffset;
+              final slots = [
+                _slotData(PlayerRenderSlotRole.previous),
+                _slotData(PlayerRenderSlotRole.current),
+                _slotData(PlayerRenderSlotRole.next),
+              ];
+              return Stack(
+                key: const Key('player-render-stack'),
+                fit: StackFit.expand,
+                clipBehavior: Clip.hardEdge,
+                children: [
+                  const ColoredBox(
+                    key: Key('player-fallback-background'),
+                    color: AppColors.mediaBlack,
+                  ),
+                  for (final slot in slots)
+                    _positionedSurface(
+                      slot,
+                      pageOffset: pageOffset,
+                      viewportHeight: viewportHeight,
+                      fallbackPage: _fallbackPage(slot.role, currentPage),
+                    ),
+                ],
+              );
+            },
+          );
+        },
+      ),
+    );
+  }
+
+  PlayerRenderSlotData _slotData(PlayerRenderSlotRole role) {
+    return widget.slots[role] ?? PlayerRenderSlotData.empty(role);
+  }
+
+  double _pageOffset() {
+    if (!widget.pageController.hasClients) {
+      return widget.pageController.initialPage.toDouble();
+    }
+    final position = widget.pageController.position;
+    if (!position.hasPixels ||
+        !position.hasViewportDimension ||
+        position.viewportDimension <= 0) {
+      return widget.pageController.initialPage.toDouble();
+    }
+    return position.pixels / position.viewportDimension;
+  }
+
+  double _fallbackPage(PlayerRenderSlotRole role, double currentPage) {
+    return switch (role) {
+      PlayerRenderSlotRole.previous => currentPage - 1,
+      PlayerRenderSlotRole.current => currentPage,
+      PlayerRenderSlotRole.next => currentPage + 1,
+    };
+  }
+
+  Widget _positionedSurface(
+    PlayerRenderSlotData slot, {
+    required double pageOffset,
+    required double viewportHeight,
+    required double fallbackPage,
+  }) {
+    final slotPage = slot.pagePosition ?? fallbackPage;
+    final offset = (slotPage - pageOffset) * viewportHeight;
+    return Positioned.fill(
+      child: Transform.translate(
+        key: Key('player-render-transform-${slot.role.name}'),
+        offset: Offset(0, offset),
+        child: PlayerVideoSurface(
+          key: ValueKey('player-render-slot-${slot.role.name}'),
+          debugSlot: slot.role.name,
+          debugIndex: slot.index,
+          showFallbackBackground: false,
+          controller: slot.controller,
+          videoUrl: slot.videoUrl,
+          theater: slot.theater,
+          placeholder: slot.placeholder,
+          warmFrameAvailable: slot.warmFrameAvailable,
+          thumbnailReady: slot.thumbnailReady,
+          posterReady: slot.posterReady,
+          fallback: slot.fallback,
+          warmSlotReused: slot.warmSlotReused,
+          waitForPlaybackFrame: slot.waitForPlaybackFrame,
+        ),
+      ),
+    );
+  }
+
+  void _log(String message) {
+    if (!kDebugMode) return;
+    debugPrint(
+      '[player-render] ts=${DateTime.now().millisecondsSinceEpoch} $message',
+    );
+  }
+}