完善契约与客户端、服务端的收发代码

SHH.CameraDashboard/Pages/CameraWall/ViewModelBase.cs

@@ -0,0 +1,24 @@
+using System.ComponentModel;
+using System.Runtime.CompilerServices;
+
+namespace SHH.CameraDashboard
+{
+    public class ViewModelBase : INotifyPropertyChanged
+    {
+        public event PropertyChangedEventHandler? PropertyChanged;
+
+        protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
+        {
+            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+        }
+
+        // 辅助方法：设置属性值并触发通知
+        protected bool SetProperty<T>(ref T field, T value, [CallerMemberName] string propertyName = null)
+        {
+            if (EqualityComparer<T>.Default.Equals(field, value)) return false;
+            field = value;
+            OnPropertyChanged(propertyName);
+            return true;
+        }
+    }
+}