ES-975464 - Resolve the ReadMe file length issue in this sample repository

Author: SreemonPremkumarM

README.md

@@ -1,2 +1,50 @@
-# How to change the checkbox column values based on selection in wpf treegrid?
-This sample illustrates how to change the checkbox column values based on selection in wpf treegrid
+# How to change the checkbox column values based on selection in wpf treegrid
+
+This sample illustrates how to change the checkbox column values based on selection in [WPF TreeGrid](https://www.syncfusion.com/wpf-controls/treegrid).
+
+In `TreeGrid`, you can select multiple rows using the [SelectionMode](https://help.syncfusion.com/cr/wpf/Syncfusion.UI.Xaml.Grid.SfGridBase.html#Syncfusion_UI_Xaml_Grid_SfGridBase_SelectionMode) property. You can process the CheckBoxSelection using [TreeGridCheckBoxColumn](https://help.syncfusion.com/cr/wpf/Syncfusion.UI.Xaml.TreeGrid.TreeGridCheckBoxColumn.html) and a boolean property called `IsSelected` in Model. You can also select all the rows in `TreeGrid` by defining the CheckBox in header cell of `GridCheckBoxColumn` using [GridColumn.HeaderTemplate](https://help.syncfusion.com/cr/wpf/Syncfusion.UI.Xaml.TreeGrid.SfTreeGrid.html#Syncfusion_UI_Xaml_TreeGrid_SfTreeGrid_HeaderTemplate).
+
+``` c#
+public static class Commands
+{
+    static Commands()
+    {
+        CommandManager.RegisterClassCommandBinding(typeof(CheckBox), new CommandBinding(CheckAndUnCheck, OnCheckUnCheckCommand, OnCanExecuteCheckAndUnCheck));
+    }
+
+    public static RoutedCommand CheckAndUnCheck = new RoutedCommand("CheckAndUnCheck", typeof(CheckBox));
+
+    private static void OnCheckUnCheckCommand(object sender, ExecutedRoutedEventArgs args)
+    {
+        var treegrid = (args.Parameter as SfTreeGrid);
+        var viewmodel = (treegrid.DataContext as ViewModel);
+        var checkbox = (sender as CheckBox).IsChecked;
+        if (viewmodel != null)
+        {
+            if (checkbox == true)
+            {
+                treegrid.SelectAll();
+                foreach (var collection in viewmodel.EmployeeInfo)
+                {
+                    if (collection.IsSelected == false)
+                        collection.IsSelected = true;
+                }
+            }
+            else if (checkbox == false)
+            {
+                treegrid.ClearSelections(false);
+                foreach (var collection in viewmodel.EmployeeInfo)
+                {  
+                    if (collection.IsSelected == true)
+                        collection.IsSelected = false;
+                }
+            }
+        }
+    }
+
+    private static void OnCanExecuteCheckAndUnCheck(object sender, CanExecuteRoutedEventArgs args)
+    {
+        args.CanExecute = true;
+    }     
+}
+```