improve:PPT墨迹管理

Ink Canvas/MainWindow_cs/MW_PPT.cs

@@ -96,6 +96,8 @@ namespace Ink_Canvas
         
         // 当前播放页码跟踪
         private int _currentSlideShowPosition = 0;
+        private readonly object _slideSwitchLock = new object();
+        private bool _isProcessingSlideSwitch = false;
 
         private DispatcherTimer _exitPPTModeAfterDisconnectTimer;
         private const int ExitPPTModeAfterDisconnectDelayMs = 1200; 
@@ -887,12 +889,18 @@ namespace Ink_Canvas
                 int currentSlide = wn.View.CurrentShowPosition;
                 int totalSlides = wn.Presentation.Slides.Count;
 
+                lock (_slideSwitchLock)
+                {
                     if (currentSlide == _currentSlideShowPosition) return;
+                    if (_isProcessingSlideSwitch) return;
+
+                    _isProcessingSlideSwitch = true;
+                    int prev = _currentSlideShowPosition;
 
                     Application.Current.Dispatcher.Invoke(() =>
                     {
-                    int prev = _currentSlideShowPosition;
-
+                        try
+                        {
                             if (inkCanvas.Strokes.Count > 0 && prev > 0 && prev != currentSlide)
                                 _singlePPTInkManager?.SaveCurrentSlideStrokes(prev, inkCanvas.Strokes);
 
@@ -905,13 +913,22 @@ namespace Ink_Canvas
 
                             _singlePPTInkManager?.LockInkForSlide(currentSlide);
                             _pptUIManager?.UpdateCurrentSlideNumber(currentSlide, totalSlides);
-                });
-
+                        }
+                        finally
+                        {
                             _currentSlideShowPosition = currentSlide;
+                            _isProcessingSlideSwitch = false;
+                        }
+                    });
+                }
             }
             catch (Exception ex)
             {
                 LogHelper.WriteLogToFile($"处理幻灯片切换事件失败: {ex}", LogHelper.LogType.Error);
+                lock (_slideSwitchLock)
+                {
+                    _isProcessingSlideSwitch = false;
+                }
             }
         }
 
@@ -1280,6 +1297,10 @@ namespace Ink_Canvas
                 
                 // 重置当前播放页码跟踪
                 _currentSlideShowPosition = 0;
+                lock (_slideSwitchLock)
+                {
+                    _isProcessingSlideSwitch = false;
+                }
 
 
                 LogHelper.WriteLogToFile("PPT状态变量已重置", LogHelper.LogType.Trace);