优化录制页性能

lib/features/recording/view-model/view_model_recording.dart

@@ -8,6 +8,7 @@ import 'package:recording_tool/features/recording/model/model_recording.dart';
 import 'package:recording_tool/features/recording/model/model_recording_context.dart';
 import 'package:recording_tool/features/recording/model/model_recording_session.dart';
 import 'package:recording_tool/features/recording/platform/recording_platform.dart';
+import 'package:recording_tool/features/recording/utils/recording_performance.dart';
 
 /// 录制页状态 Provider。
 final recordingViewModelProvider =
@@ -32,6 +33,8 @@ class RecordingRequiredPermissions {
 class RecordingViewModel extends Notifier<RecordingModel> {
   Timer? _elapsedTimer;
   DateTime? _recordingStartedAt;
+  RecordingRequiredPermissions? _cachedRequiredPermissions;
+  var _sessionGeneration = 0;
 
   /// 初始化状态并注册销毁回调。
   @override
@@ -52,55 +55,88 @@ class RecordingViewModel extends Notifier<RecordingModel> {
     state = state.copyWith(recordingContext: recordingContext);
   }
 
-  /// 申请权限并检查系统设置。
-  Future<void> prepareSession() async {
+  /// 准备相机和麦克风权限；已授权时复用当前会话结果。
+  Future<RecordingRequiredPermissions> prepareRequiredPermissions({
+    bool forceRefresh = false,
+  }) async {
+    final generation = _sessionGeneration;
     if (!RecordingPlatform.isSupported) {
       _updateSession((s) => s.copyWith(errorMessage: '当前设备不支持录制'));
-      return;
+      return const RecordingRequiredPermissions(
+        cameraGranted: false,
+        microphoneGranted: false,
+      );
     }
 
-    final permissions = await PermissionService.requestMissing([
-      Permission.camera,
-      Permission.microphone,
-      if (Platform.isAndroid) Permission.notification,
-    ]);
-
-    final cameraGranted = permissions[Permission.camera]?.isGranted ?? false;
-    if (!cameraGranted) {
-      _updateSession((s) => s.copyWith(errorMessage: '需要相机权限才能录制'));
-      return;
+    final cached = _cachedRequiredPermissions;
+    if (!forceRefresh && cached?.allGranted == true) {
+      return cached!;
     }
 
-    final microphoneGranted =
-        permissions[Permission.microphone]?.isGranted ?? false;
+    final permissions = await measureRecordingOperation(
+      'required permissions',
+      () => PermissionService.requestMissing([
+        Permission.camera,
+        Permission.microphone,
+      ]),
+    );
+    final result = RecordingRequiredPermissions(
+      cameraGranted: _isPermissionGranted(permissions[Permission.camera]),
+      microphoneGranted: _isPermissionGranted(
+        permissions[Permission.microphone],
+      ),
+    );
+    if (generation != _sessionGeneration) return result;
+    _cachedRequiredPermissions = result;
+    final errorMessage = !result.cameraGranted
+        ? '需要相机权限才能录制'
+        : (!result.microphoneGranted ? '需要录音权限才能录制' : null);
+
+    _updateSession(
+      (s) => s.copyWith(
+        isMicrophoneGranted: result.microphoneGranted,
+        errorMessage: errorMessage,
+      ),
+    );
+    return result;
+  }
+
+  /// 加载不影响相机首帧的通知、勿扰和电池状态。
+  Future<void> loadSystemAdvisories() async {
+    final generation = _sessionGeneration;
+    final notificationFuture = Platform.isAndroid
+        ? PermissionService.requestMissing([Permission.notification])
+        : Future.value(<Permission, PermissionStatus>{});
+    final results = await measureRecordingOperation(
+      'system advisories',
+      () => Future.wait<dynamic>([
+        notificationFuture,
+        RecordingPlatform.hasNotificationPolicyAccess(),
+        RecordingPlatform.isIgnoringBatteryOptimizations(),
+      ]),
+    );
+    final notificationPermissions =
+        results[0] as Map<Permission, PermissionStatus>;
     final notificationsGranted = Platform.isAndroid
-        ? (permissions[Permission.notification]?.isGranted ?? false)
+        ? _isPermissionGranted(notificationPermissions[Permission.notification])
         : true;
-
+    final hasDnd = results[1] as bool;
+    final batteryIgnored = results[2] as bool;
+    if (generation != _sessionGeneration) return;
     final warnings = <String>[];
     if (Platform.isAndroid && !notificationsGranted) {
       warnings.add('未授予通知权限，录制时可能看不到前台服务通知，系统更容易结束后台录制');
     }
-    if (!microphoneGranted) {
-      warnings.add('未授予麦克风权限，当前将以静音模式录制');
-    }
-    final hasDnd = await RecordingPlatform.hasNotificationPolicyAccess();
-    final batteryIgnored =
-        await RecordingPlatform.isIgnoringBatteryOptimizations();
 
     _updateSession(
       (s) => s.copyWith(
         hasDndAccess: hasDnd,
         isBatteryOptimizedIgnored: batteryIgnored,
-        isMicrophoneGranted: microphoneGranted,
         notificationsGranted: notificationsGranted,
         permissionWarning: warnings.isEmpty ? null : warnings.join('\n'),
-        errorMessage: null,
         clearPermissionWarning: warnings.isEmpty,
       ),
     );
-
-    _updateSession((s) => s.copyWith(errorMessage: null));
   }
 
   void setPreviewReady({required bool ready, String? errorMessage}) {
@@ -112,27 +148,8 @@ class RecordingViewModel extends Notifier<RecordingModel> {
   /// 检测并尝试申请相机、麦克风权限，同步更新 session 中的 isMicrophoneGranted。
   Future<RecordingRequiredPermissions>
   ensureCameraAndMicrophonePermissions() async {
-    final permissions = await PermissionService.requestMissing([
-      Permission.camera,
-      Permission.microphone,
-    ]);
-
-    final cameraGranted = _isPermissionGranted(permissions[Permission.camera]);
-    final microphoneGranted = _isPermissionGranted(
-      permissions[Permission.microphone],
-    );
-
-    _updateSession((s) => s.copyWith(isMicrophoneGranted: microphoneGranted));
-
-    if (cameraGranted && !state.session.isPreviewReady) {
-      _updateSession((s) => s.copyWith(errorMessage: null));
-      _updateSession((s) => s.copyWith(isPreviewReady: true));
-    }
-
-    return RecordingRequiredPermissions(
-      cameraGranted: cameraGranted,
-      microphoneGranted: microphoneGranted,
-    );
+    final cached = _cachedRequiredPermissions;
+    return prepareRequiredPermissions(forceRefresh: cached?.allGranted != true);
   }
 
   bool _isPermissionGranted(PermissionStatus? status) {
@@ -282,11 +299,13 @@ class RecordingViewModel extends Notifier<RecordingModel> {
 
   /// 退出录制页时释放勿扰和会话状态（沉浸式由页面统一恢复）。
   Future<void> teardown() async {
-    await RecordingPlatform.disableDoNotDisturb();
+    _sessionGeneration++;
+    _cachedRequiredPermissions = null;
     _recordingStartedAt = null;
     _elapsedTimer?.cancel();
     _elapsedTimer = null;
     state = state.copyWith(session: const RecordingSessionState());
+    await RecordingPlatform.disableDoNotDisturb();
   }
 
   /// Provider 销毁时取消状态流订阅。