WPF 为什么分配的背景不能覆盖样式触发器中的设置器值？

Question

我有一个Style 用于TextBox，如下所示：

<Style x:Key="TextBox_Standard" TargetType="{x:Type TextBoxBase}" >
    <Setter Property="Control.FontFamily" Value="/#Calibri" />
    <Setter Property="Control.FontSize" Value="12" />
    <Setter Property="Control.Margin" Value="2" />
    <Setter Property="Control.Height" Value="21" />
    <Setter Property="Control.VerticalAlignment" Value="Center" />
    <Setter Property="SnapsToDevicePixels" Value="True"/>
    <Setter Property="UndoLimit" Value="0"/>
    <Setter Property="Template">
        <Setter.Value>
          <ControlTemplate TargetType="{x:Type TextBoxBase}">
            <Border 
              Name="Border"
              CornerRadius="1" 
              Padding="1"
              Background="{StaticResource WindowBackgroundBrush}"
              BorderBrush="{StaticResource SolidBorderBrush}"
              BorderThickness="1" >
              <ScrollViewer Margin="0" x:Name="PART_ContentHost" />
            </Border>
            <ControlTemplate.Triggers>
                <Trigger Property="IsEnabled" Value="False">
                    <Setter TargetName="Border" Property="Background" Value="{StaticResource DisabledBackgroundBrush}"/>
                    <Setter Property="Foreground" Value="{StaticResource DisabledForegroundBrush}"/>
                    <Setter Property="Cursor" Value="Arrow"/>
                </Trigger>
                <Trigger Property="IsReadOnly" Value="True">
                    <Setter TargetName="Border" Property="Background" Value="{StaticResource DisabledBackgroundBrush}"/>
                    <Setter Property="Focusable" Value="False"/>
                    <Setter Property="Cursor" Value="Arrow"/>
                </Trigger>
            </ControlTemplate.Triggers>
          </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

它是为了确保在不可编辑时前景色为黑色，背景色为灰色。

但显然现在需要在背景不可编辑时以编程方式更改背景，所以我这样尝试：

txtBox.Background = Brushes.Yellow;

但是发生的情况是它在可编辑时仍然具有白色背景，而在不可编辑时仍然具有灰色背景。

我哪里做错了？

Answer 1

试试这个

   <Style x:Key="TextBox_Standard" TargetType="{x:Type TextBoxBase}" >
        <Setter Property="Control.FontFamily" Value="/#Calibri" />
        <Setter Property="Control.FontSize" Value="12" />
        <Setter Property="Control.Margin" Value="2" />
        <Setter Property="Control.Height" Value="21" />
        <Setter Property="Control.VerticalAlignment" Value="Center" />
        <Setter Property="SnapsToDevicePixels" Value="True"/>
        <Setter Property="Background" Value="{StaticResource WindowBackgroundBrush}"></Setter>
        <Setter Property="UndoLimit" Value="0"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type TextBoxBase}">
                    <Border  
          Name="Border" 
          CornerRadius="1"  
          Padding="1" 
          Background="{TemplateBinding Background}" 
          BorderBrush="{StaticResource SolidBorderBrush}" 
          BorderThickness="1" >
                        <ScrollViewer Margin="0" x:Name="PART_ContentHost" />
                    </Border>
                    <ControlTemplate.Triggers>

                        <Trigger Property="IsEnabled" Value="False">
                            <Setter TargetName="Border" Property="Background" Value="{StaticResource DisabledBackgroundBrush}"/>
                            <Setter Property="Foreground" Value="{StaticResource DisabledForegroundBrush}"/>
                            <Setter Property="Cursor" Value="Arrow"/>
                        </Trigger>
                        <Trigger Property="IsReadOnly" Value="True">
                            <Setter TargetName="Border" Property="Background" Value="{StaticResource DisabledBackgroundBrush}"/>
                            <Setter Property="Focusable" Value="False"/>
                            <Setter Property="Cursor" Value="Arrow"/>
                        </Trigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>