add:issue #224

Ink Canvas/MainWindow_cs/MW_ElementsControls.cs

@@ -1493,7 +1493,7 @@ namespace Ink_Canvas
         #region Image Resize Handles
 
         // 图片缩放选择点相关变量
-        private bool isResizingImage = false;
+        private bool isResizingImage;
         private Point imageResizeStartPoint;
         private string activeResizeHandle = "";
 

Ink Canvas/MainWindow_cs/MW_Eraser.cs

@@ -13,14 +13,14 @@ namespace Ink_Canvas
     public partial class MainWindow : Window
     {
         // 橡皮擦系统核心变量
-        public bool isUsingGeometryEraser = false;
-        private IncrementalStrokeHitTester hitTester = null;
+        public bool isUsingGeometryEraser;
+        private IncrementalStrokeHitTester hitTester;
 
         public double eraserWidth = 64;
-        public bool isEraserCircleShape = false;
-        public bool isUsingStrokesEraser = false;
+        public bool isEraserCircleShape;
+        public bool isUsingStrokesEraser;
 
-        private Matrix scaleMatrix = new Matrix();
+        private Matrix scaleMatrix;
 
         // 橡皮擦覆盖层相关控件
         private System.Windows.Controls.Canvas eraserOverlayCanvas;

Ink Canvas/MainWindow_cs/MW_PPT.cs

@@ -91,8 +91,8 @@ namespace Ink_Canvas
         private const int ProcessMonitorInterval = 1000; // 应用程序监控间隔（毫秒）
         
         // 上次播放位置相关字段
-        private int _lastPlaybackPage = 0;
-        private bool _shouldNavigateToLastPage = false;
+        private int _lastPlaybackPage;
+        private bool _shouldNavigateToLastPage;
         
         // 页面切换防抖机制
         private DateTime _lastSlideSwitchTime = DateTime.MinValue;

Ink Canvas/MainWindow_cs/MW_SelectionGestures.cs

@@ -255,12 +255,12 @@ namespace Ink_Canvas
         #endregion
 
         private bool isGridInkCanvasSelectionCoverMouseDown;
-        private bool isStrokeDragging = false;
+        private bool isStrokeDragging;
         private Point strokeDragStartPoint;
         private StrokeCollection StrokesSelectionClone = new StrokeCollection();
 
         // 选择框和选择点相关变量
-        private bool isResizing = false;
+        private bool isResizing;
         private string currentResizeHandle = "";
         private Point resizeStartPoint;
         private Rect originalSelectionBounds;

Ink Canvas/MainWindow_cs/MW_Settings.cs

@@ -2516,6 +2516,44 @@ namespace Ink_Canvas
             SaveSettingsToFile();
         }
 
+        private void ToggleSwitchUseLegacyTimerUI_Toggled(object sender, RoutedEventArgs e)
+        {
+            if (!isLoaded) return;
+            Settings.RandSettings.UseLegacyTimerUI = ToggleSwitchUseLegacyTimerUI.IsOn;
+            SaveSettingsToFile();
+        }
+
+        private void TimerVolumeSlider_ValueChanged(object sender, RoutedEventArgs e)
+        {
+            if (!isLoaded) return;
+            Settings.RandSettings.TimerVolume = TimerVolumeSlider.Value;
+            SaveSettingsToFile();
+        }
+
+        private void ButtonSelectCustomTimerSound_Click(object sender, RoutedEventArgs e)
+        {
+            Microsoft.Win32.OpenFileDialog openFileDialog = new Microsoft.Win32.OpenFileDialog
+            {
+                Title = "选择计时器提醒铃声",
+                Filter = "音频文件 (*.wav)|*.wav|所有文件 (*.*)|*.*",
+                DefaultExt = "wav"
+            };
+
+            if (openFileDialog.ShowDialog() == true)
+            {
+                Settings.RandSettings.CustomTimerSoundPath = openFileDialog.FileName;
+                SaveSettingsToFile();
+                MessageBox.Show("自定义铃声设置成功！", "设置成功", MessageBoxButton.OK, MessageBoxImage.Information);
+            }
+        }
+
+        private void ButtonResetTimerSound_Click(object sender, RoutedEventArgs e)
+        {
+            Settings.RandSettings.CustomTimerSoundPath = "";
+            SaveSettingsToFile();
+            MessageBox.Show("已重置为默认铃声！", "重置成功", MessageBoxButton.OK, MessageBoxImage.Information);
+        }
+
         private void ToggleSwitchShowRandomAndSingleDraw_Toggled(object sender, RoutedEventArgs e)
         {
             if (!isLoaded) return;

Ink Canvas/MainWindow_cs/MW_SettingsToLoad.cs

@@ -856,6 +856,10 @@ namespace Ink_Canvas
                 RandomDrawPanel.Visibility = Settings.RandSettings.ShowRandomAndSingleDraw ? Visibility.Visible : Visibility.Collapsed;
                 SingleDrawPanel.Visibility = Settings.RandSettings.ShowRandomAndSingleDraw ? Visibility.Visible : Visibility.Collapsed;
 
+                // 计时器设置
+                ToggleSwitchUseLegacyTimerUI.IsOn = Settings.RandSettings.UseLegacyTimerUI;
+                TimerVolumeSlider.Value = Settings.RandSettings.TimerVolume;
+
                 // 加载自定义点名背景
                 UpdatePickNameBackgroundsInComboBox();
 
@@ -874,6 +878,8 @@ namespace Ink_Canvas
                 RandWindowOnceMaxStudentsSlider.Value = Settings.RandSettings.RandWindowOnceMaxStudents;
                 ToggleSwitchExternalCaller.IsOn = Settings.RandSettings.DirectCallCiRand;
                 ComboBoxExternalCallerType.SelectedIndex = Settings.RandSettings.ExternalCallerType;
+                ToggleSwitchUseLegacyTimerUI.IsOn = Settings.RandSettings.UseLegacyTimerUI;
+                TimerVolumeSlider.Value = Settings.RandSettings.TimerVolume;
             }
 
             // ModeSettings

Ink Canvas/MainWindow_cs/MW_Timer.cs

@@ -71,10 +71,10 @@ namespace Ink_Canvas
         private DateTime cachedNetworkTime = DateTime.Now;
         private DateTime lastNtpSyncTime = DateTime.MinValue;
         private string lastDisplayedTime = ""; 
-        private bool useNetworkTime = false; 
+        private bool useNetworkTime; 
         private TimeSpan networkTimeOffset = TimeSpan.Zero;
         private DateTime lastLocalTime = DateTime.Now; // 记录上次的本地时间，用于检测时间跳跃
-        private bool isNtpSyncing = false; // 防止重复NTP同步的标志 
+        private bool isNtpSyncing; // 防止重复NTP同步的标志 
 
         private async Task<DateTime> GetNetworkTimeAsync()
         {

Ink Canvas/MainWindow_cs/MW_TouchEvents.cs

@@ -24,8 +24,7 @@ namespace Ink_Canvas
         private InkCanvasEditingMode lastInkCanvasEditingMode = InkCanvasEditingMode.Ink;
         private DateTime lastTouchDownTime = DateTime.MinValue;
         private const double MULTI_TOUCH_DELAY_MS = 100; 
-        private bool isInWritingMode = false;
-        private bool isMultiTouchTimerActive = false;
+        private bool isMultiTouchTimerActive;
         
         /// </summary> 
         /// 保存画布上的非笔画元素（如图片、媒体元素等）