Merge pull request #521 from GF-Huang/master

Add attached property "DataGridAttach.ClickBlankUnselect".

src/Shared/HandyControlDemo_Shared/UserControl/Styles/DataGridDemoCtl.xaml

@@ -9,7 +9,7 @@
     <hc:TransitioningContentControl>
         <TabControl Style="{StaticResource TabControlInLine}">
             <TabItem Header="{ex:Lang Key={x:Static langs:LangKeys.Common}}">
-                <DataGrid HeadersVisibility="All" RowHeaderWidth="60" AutoGenerateColumns="False" ItemsSource="{Binding DataList}">
+                <DataGrid hc:DataGridAttach.CanUnselectRowsWithBlankArea="True" HeadersVisibility="All" RowHeaderWidth="60" AutoGenerateColumns="False" ItemsSource="{Binding DataList}">
                     <DataGrid.RowHeaderTemplate>
                         <DataTemplate>
                             <CheckBox IsChecked="{Binding IsSelected,RelativeSource={RelativeSource AncestorType=DataGridRow}}"/>

src/Shared/HandyControl_Shared/Controls/Attach/DataGridAttach.cs

@@ -2,6 +2,7 @@ using System.Linq;
 using System.Windows;
 using System.Windows.Controls;
 using System.Windows.Controls.Primitives;
+using System.Windows.Input;
 using HandyControl.Data;
 
 namespace HandyControl.Controls
@@ -307,5 +308,38 @@ namespace HandyControl.Controls
         }
 
         private static void DataGrid_LoadingRow(object sender, DataGridRowEventArgs e) => e.Row.Header = (e.Row.GetIndex() + 1).ToString();
+
+        public static readonly DependencyProperty CanUnselectAllWithBlankAreaProperty = DependencyProperty.RegisterAttached(
+            "CanUnselectAllWithBlankArea", typeof(bool), typeof(DataGridAttach), new PropertyMetadata(ValueBoxes.FalseBox, OnCanUnselectAllWithBlankAreaChanged));
+
+        private static void OnCanUnselectAllWithBlankAreaChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
+        {
+            if (d is DataGrid dataGrid)
+            {
+                if ((bool)e.NewValue)
+                {
+                    dataGrid.PreviewMouseDown += DataGrid_PreviewMouseDown;
+                }
+                else
+                {
+                    dataGrid.PreviewMouseDown -= DataGrid_PreviewMouseDown;
+                }
+            }
+        }
+
+        private static void DataGrid_PreviewMouseDown(object sender, MouseButtonEventArgs e)
+        {
+            if (sender is DataGrid dataGrid && e.OriginalSource is System.Windows.Controls.ScrollViewer)
+            {
+                dataGrid.CommitEdit();
+                dataGrid.UnselectAll();
+            }
+        }
+
+        public static void SetCanUnselectAllWithBlankArea(DependencyObject element, bool value)
+            => element.SetValue(CanUnselectAllWithBlankAreaProperty, value);
+
+        public static bool GetCanUnselectAllWithBlankArea(DependencyObject element)
+            => (bool) element.GetValue(CanUnselectAllWithBlankAreaProperty);
     }
 }