我找到了解决方案，但它看起来并不优雅。
基本问题是：
DataGrid.IsFocused是永久false的，因为焦点有具体的单元格，而不是网格本身。- 无法确定单元格样式，网格中是否有任何焦点单元格。您只能测试
IsFocused当前单元格。
- 数据网格不会对父窗口的停用做出反应。
确定数据网格是否具有焦点的唯一方法是检查DataGrid.CurrentCell属性。不幸的是，它是一个结构，你不能创建一个触发器来检查这个属性{x:Null}。
为了解决这些问题，我需要两个附加属性。
首先，它们旨在确定网格中是否有任何聚焦单元格。结果一定是bool，源是DataGridCellInfo，所以，首先，转换器一定要写成：
[ValueConversion(typeof(DataGridCellInfo), typeof(bool))]
public sealed class DataGridCellInfoToBooleanConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
if (value == null || value.GetType() != typeof(DataGridCellInfo) || targetType != typeof(bool))
return DependencyProperty.UnsetValue;
// IsValid will be false, if there's no focused cell.
return ((DataGridCellInfo)value).IsValid;
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
return DependencyProperty.UnsetValue;
}
}
附带属性：
public static bool GetHasFocusedCell(DependencyObject obj)
{
return (bool)obj.GetValue(HasFocusedCellProperty);
}
public static void SetHasFocusedCell(DependencyObject obj, bool value)
{
obj.SetValue(HasFocusedCellProperty, value);
}
public static readonly DependencyProperty HasFocusedCellProperty = DependencyProperty.RegisterAttached(
"HasFocusedCell",
typeof(bool),
typeof(FocusedCellBehavior),
new UIPropertyMetadata(false));
当网格的父窗口变为不活动时，必须更改第二个附加属性：
public static bool GetIsParentWindowActive(DependencyObject obj)
{
return (bool)obj.GetValue(IsParentWindowActiveProperty);
}
public static void SetIsParentWindowActive(DependencyObject obj, bool value)
{
obj.SetValue(IsParentWindowActiveProperty, value);
}
public static readonly DependencyProperty IsParentWindowActiveProperty = DependencyProperty.RegisterAttached(
"IsParentWindowActive",
typeof(bool),
typeof(FocusedCellBehavior),
new UIPropertyMetadata(false));
现在，让我们在 XAML 中绑定附加属性：
<!-- A converter to define, is there any focused cell in DataGrid -->
<local:DataGridCellInfoToBooleanConverter x:Key="DataGridCellInfoToBooleanConverter"/>
<DataGrid Grid.Row="0" SelectionUnit="FullRow" SelectionMode="Single"
ItemsSource="{Binding}"
local:FocusedCellBehavior.HasFocusedCell="{Binding CurrentCell, RelativeSource={RelativeSource Mode=Self}, Converter={StaticResource DataGridCellInfoToBooleanConverter}}"
local:FocusedCellBehavior.IsParentWindowActive="{Binding IsActive, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type Window}}}"/>
接下来，我需要一个单元格样式来设置适当的背景颜色：
<!-- A style of selected cell in DataGrid, when there's no any focused cells in DataGrid -->
<Style TargetType="{x:Type DataGridCell}" x:Key="InactiveSelectedCellStyle">
<Style.Triggers>
<Trigger Property="IsSelected" Value="True">
<Setter Property="Background" Value="{DynamicResource {x:Static SystemColors.ControlBrushKey}}"/>
</Trigger>
</Style.Triggers>
</Style>
以及触发触发器的网格样式，当附加属性将更改其值时：
<!--
A style of DataGrid, that defines a couple of triggers, which being fired
when helper attached properties will change their values
-->
<Style TargetType="{x:Type DataGrid}">
<Style.Triggers>
<Trigger Property="local:FocusedCellBehavior.IsParentWindowActive" Value="False">
<Setter Property="CellStyle" Value="{StaticResource InactiveSelectedCellStyle}"/>
</Trigger>
<Trigger Property="local:FocusedCellBehavior.HasFocusedCell" Value="False">
<Setter Property="CellStyle" Value="{StaticResource InactiveSelectedCellStyle}"/>
</Trigger>
</Style.Triggers>
</Style>
有没有更好的解决方案？
