fix(player): 收紧图片与快速切集资源占用

lib/core/data/services/playback_session.dart

@@ -81,6 +81,8 @@ class PlaybackSession extends ChangeNotifier {
   // Includes initialization and asynchronous disposal, until native release ends.
   int get livePlayerCount => _live.length;
   int? get preloadedIndex => _next?.prepared == true ? _next?.index : null;
+  int? get previousPreloadedIndex =>
+      _previous?.prepared == true ? _previous?.index : null;
   Future<void> get playbackSettled => _operations;
   Future<void> get preloadSettled => _preloadTask;
 

lib/core/data/services/sprite_thumbnail_axis.dart

@@ -9,7 +9,7 @@ import '../../config/app_config.dart';
 import 'sprite_thumbnail_asset_loader.dart';
 
 const Duration spriteVttCacheTtl = Duration(minutes: 10);
-const int spriteImageCacheCapacity = 2;
+const int spriteImageCacheCapacity = 1;
 
 /// 单个 VTT cue 对应的 sprite 裁剪区域。
 class SpriteThumbnailCue {
@@ -148,7 +148,6 @@ class SpriteThumbnailAxisService extends ChangeNotifier
   final Set<String> _failedSprites = {};
   bool _disposed = false;
 
-  @visibleForTesting
   int get spriteCacheSize => _spriteCache.length;
 
   @visibleForTesting
@@ -156,7 +155,7 @@ class SpriteThumbnailAxisService extends ChangeNotifier
       .map((url) => Uri.tryParse(url)?.pathSegments.lastOrNull ?? url)
       .toList();
 
-  /// 播放器就绪时预取当前 cue 与相邻 sprite，拖动帧不触发网络或解码。
+  /// 播放器就绪时预取当前 cue；容量大于 1 时顺带预取相邻 sprite。
   @override
   Future<void> prepareAt(String? thumbnailsUrl, Duration position) async {
     final url = _normalizeUrl(thumbnailsUrl);
@@ -269,6 +268,7 @@ class SpriteThumbnailAxisService extends ChangeNotifier
     if (current == null) return const [];
     final index = axis.cues.indexOf(current);
     final candidates = <SpriteThumbnailCue>[current];
+    if (spriteCacheCapacity <= 1) return candidates;
     for (final direction in const [1, -1]) {
       for (var step = 1; step < axis.cues.length; step++) {
         final neighborIndex = index + direction * step;

lib/core/widgets/remote_image.dart

@@ -5,6 +5,24 @@ import 'package:flutter/material.dart';
 import '../config/app_config.dart';
 import '../theme/app_colors.dart';
 
+const int _minImageDecodePixels = 96;
+const int _maxImageDecodePixels = 2048;
+
+/// 将布局逻辑尺寸换算成有限像素尺寸，兼顾小头像和全屏首帧。
+int resolveImageDecodePixels(double? logicalExtent, double devicePixelRatio) {
+  final ratio = devicePixelRatio.isFinite && devicePixelRatio > 0
+      ? devicePixelRatio
+      : 1.0;
+  final extent =
+      logicalExtent != null && logicalExtent.isFinite && logicalExtent > 0
+      ? logicalExtent
+      : 120.0;
+  return (extent * ratio)
+      .ceil()
+      .clamp(_minImageDecodePixels, _maxImageDecodePixels)
+      .toInt();
+}
+
 /// 封面图统一入口：后端给的是相对路径，这里补服务地址并处理加载失败。
 class RemoteImage extends StatelessWidget {
   const RemoteImage(
@@ -17,6 +35,8 @@ class RemoteImage extends StatelessWidget {
     this.fallbackIconKey,
     this.fallbackAspectRatio,
     this.fallbackColor = AppColors.raised,
+    this.decodeWidth,
+    this.decodeHeight,
   });
 
   final String path;
@@ -27,21 +47,56 @@ class RemoteImage extends StatelessWidget {
   final Key? fallbackIconKey;
   final double? fallbackAspectRatio;
   final Color fallbackColor;
+  final int? decodeWidth;
+  final int? decodeHeight;
 
   @override
   Widget build(BuildContext context) {
     final url = AppConfig.mediaUrl(path);
     if (url.isEmpty) return _fallback(brand: showFallbackIcon);
-    return Image.network(
-      url,
-      width: width,
-      height: height,
-      fit: fit,
-      gaplessPlayback: true,
-      errorBuilder: (_, _, _) => _fallback(brand: showFallbackIcon),
-      frameBuilder: (context, child, frame, wasSynchronouslyLoaded) {
-        if (wasSynchronouslyLoaded || frame != null) return child;
-        return _fallback(brand: showFallbackIcon);
+    return LayoutBuilder(
+      builder: (context, constraints) {
+        final pixelRatio = MediaQuery.devicePixelRatioOf(context);
+        final layoutWidth = constraints.hasBoundedWidth
+            ? constraints.maxWidth
+            : width;
+        final aspectRatio =
+            fallbackAspectRatio != null &&
+                fallbackAspectRatio!.isFinite &&
+                fallbackAspectRatio! > 0
+            ? fallbackAspectRatio
+            : null;
+        final inferredHeight = constraints.hasBoundedHeight
+            ? constraints.maxHeight
+            : height ??
+                  (layoutWidth != null && aspectRatio != null
+                      ? layoutWidth / aspectRatio
+                      : null);
+        final cacheWidth =
+            decodeWidth ?? resolveImageDecodePixels(layoutWidth, pixelRatio);
+        final cacheHeight =
+            decodeHeight ??
+            (inferredHeight == null
+                ? null
+                : resolveImageDecodePixels(inferredHeight, pixelRatio));
+        return Image.network(
+          url,
+          width: width,
+          height: height,
+          fit: fit,
+          cacheWidth: cacheWidth
+              .clamp(_minImageDecodePixels, _maxImageDecodePixels)
+              .toInt(),
+          cacheHeight: cacheHeight
+              ?.clamp(_minImageDecodePixels, _maxImageDecodePixels)
+              .toInt(),
+          gaplessPlayback: true,
+          errorBuilder: (_, _, _) => _fallback(brand: showFallbackIcon),
+          frameBuilder: (context, child, frame, wasSynchronouslyLoaded) {
+            if (wasSynchronouslyLoaded || frame != null) return child;
+            return _fallback(brand: showFallbackIcon);
+          },
+        );
       },
     );
   }