WPF：使用 ValueConverter 根据 DateTime 字段更改 DataGrid 行颜色

Question

我正在尝试以红色突出显示去年记录的项目的所有行，或者以绿色突出显示较旧的项目（属性为 RecordTime）。 我编写了一个 ValueConverter 来执行此操作，当加载 window 时，它似乎被正确调用：

    public class DateColourConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter,
        System.Globalization.CultureInfo culture)
    {
        var item = (DateTime)value;
        if (item != null)
        {
            var _lowerDT = DateTime.Now.AddYears(-1);
            if (item > _lowerDT)
            {
                //return (Color)ColorConverter.ConvertFromString("#ab2626");
                return Colors.Red;
            }
        }
        //return (Color)ColorConverter.ConvertFromString("#FF454545");
        return Colors.Green;

    }

    public object ConvertBack(object value, Type targetType, object parameter,
System.Globalization.CultureInfo culture)
    {
        throw new NotSupportedException();
    }
}

我已经在我的主 window 中声明了值转换器，如下所示：

<Window.Resources>
    <ResourceDictionary>
        <locals:DateColourConverter x:Key="DateColourConverter"/>
    </ResourceDictionary>
</Window.Resources>

DataGrid 是根据结果子集动态创建的。 这是我在 xaml 中设计它们的方式：

                <DataGrid
                        x:Name="dg_Clips"
                        Background="#FF454545" 
                        BorderBrush="{DynamicResource AvocetGoldBorderBrush}" 
                        Foreground="White" 
                        HorizontalGridLinesBrush="#FF454545" 
                        VerticalGridLinesBrush="#FF454545"
                        ItemsSource="{Binding Path=ClipMaps}"
                        AutoGenerateColumns="False"
                        ColumnHeaderStyle="{DynamicResource GreyDataGridColumnHeaderStyle}"
                        CanUserAddRows="False"
                        SelectionMode="Single" 
                        MouseRightButtonUp="DataGrid_MouseRightButtonUp"
                        IsReadOnly="True"
                        AllowDrop="True"
                        FontSize="20"
                        PreviewMouseLeftButtonDown="DataGrid_PreviewMouseLeftButtonDown"
                        CanUserResizeColumns="True"
                        CanUserReorderColumns="True"
                        Sorting="dg_Clips_Sorting"
                        CanUserSortColumns="False"
                        
                    >
                    <DataGrid.Resources>
                        <Style TargetType="DataGridColumnHeader">
                            <EventSetter Event="Click" Handler="columnHeader_Click" />
                            <EventSetter Event="MouseLeftButtonDown" Handler="columnHeader_Click" />
                            <EventSetter Event="PreviewMouseLeftButtonDown" Handler="columnHeader_Click" />
                            
                        </Style>

                        <Style TargetType="DataGridColumnHeadersPresenter">
                            <EventSetter Event="MouseLeftButtonDown" Handler="columnHeader_Click" />
                            <EventSetter Event="PreviewMouseLeftButtonDown" Handler="columnHeader_Click" />
                        </Style>

                        <Style TargetType="DataGridRow">
                            <Setter Property="Background">
                                <Setter.Value>
                                    <Binding Converter="{StaticResource DateColourConverter}" Path="RecordTime"/>
                                </Setter.Value>
                            </Setter>
                        </Style>
                    </DataGrid.Resources>


                    <DataGrid.RowStyle>
                        <Style TargetType="DataGridRow">
                            <Setter Property="Background">
                                <Setter.Value>
                                    <Binding Converter="{StaticResource DateColourConverter}" Path="RecordTime"/>
                                </Setter.Value>
                            </Setter>
                        </Style>
                    </DataGrid.RowStyle>


                    <DataGrid.Columns>
                        <DataGridTextColumn Header="MediaID"
                                                Binding="{Binding MediaID}" 
                                                Width="160"/>
                        <DataGridTextColumn Header="Title"
                                                Binding="{Binding Title}" 
                                                Width="160"/>
                        <DataGridTextColumn Header="Duration"
                                                Binding="{Binding DurationString}" 
                                                Width="120"/>
                        <DataGridTextColumn Header="Type"
                                                Binding="{Binding MediaType}" 
                                                Width="70"/>
                        <DataGridTextColumn Header="SOM"
                                                Binding="{Binding SOM}" 
                                                Width="120"/>
                        <DataGridTextColumn Header="Recorded"
                                                Binding="{Binding RecordString}" 
                                                Width="180"/>
                        <DataGridTextColumn Header="Valid From"
                                                Binding="{Binding ValidFromString}" 
                                                Width="180"/>
                        <DataGridTextColumn Header="Valid To"
                                                Binding="{Binding ValidToString}" 
                                                Width="180"/>
                        <!--<DataGridTextColumn Header="Parent Clip ID"
                                                Binding="{Binding ParentID}" 
                                                Width="160"/>-->
                        <!--Main, Location, Archive-->
                        <DataGridCheckBoxColumn Header="Main"
                                                Binding="{Binding LocationMain}" 
                                                Width="80"/>
                        <DataGridCheckBoxColumn Header="Archive"
                                                Binding="{Binding LocationArchive}" 
                                                Width="80"/>
                        <DataGridCheckBoxColumn Header="Backup"
                                                Binding="{Binding LocationBackup}" 
                                                Width="80"/>
                    </DataGrid.Columns>
                </DataGrid>

如您所见，我尝试了两种不同的设置行样式的方法，但都不起作用，数据网格没有显示不同颜色的行。 任何关于为什么会这样的帮助或建议将不胜感激。