add Screenshot Demo

src/Shared/HandyControl_Shared/Interactivity/Commands/ControlCommands.cs

@@ -161,5 +161,10 @@ namespace HandyControl.Interactivity
         ///     关闭窗口
         /// </summary>
         public static CloseWindowCommand CloseWindow { get; } = new CloseWindowCommand();
+
+        /// <summary>
+        ///     开始截图
+        /// </summary>
+        public static StartScreenshotCommand StartScreenshot { get; } = new StartScreenshotCommand();
     }
 }

src/Shared/HandyControl_Shared/Interactivity/Commands/ScreenshotCommand.cs

@@ -0,0 +1,15 @@
+using System;
+using System.Windows.Input;
+using HandyControl.Controls;
+
+namespace HandyControl.Interactivity
+{
+    public class StartScreenshotCommand : ICommand
+    {
+        public bool CanExecute(object parameter) => true;
+
+        public void Execute(object parameter) => new Screenshot().Start();
+
+        public event EventHandler CanExecuteChanged;
+    }
+}

src/Shared/HandyControl_Shared/Interactivity/Commands/StartScreenshotCommand.cs

@@ -0,0 +1,15 @@
+using System;
+using System.Windows.Input;
+using HandyControl.Controls;
+
+namespace HandyControl.Interactivity
+{
+    public class StartScreenshotCommand : ICommand
+    {
+        public bool CanExecute(object parameter) => true;
+
+        public void Execute(object parameter) => new Screenshot().Start();
+
+        public event EventHandler CanExecuteChanged;
+    }
+}