WPF 用户控件焦点

Question

我有一个UserControl 子类，其中包含一个Grid，而该子类又包含一对TextBlocks 和一个Border（其中还包含一个TextBlock）。请参阅下面的代码。

    <UserControl x:Class="ProjectNS.MyUserControl"
       xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
       xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
       xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
       xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
       xmlns:my="clr-namespace:ProjectNS"
       mc:Ignorable="d" 
       Height="49" Width="150" BottomResizeLocked="True" TopResizeLocked="True"  
       MoveLocks="Vertical" Margin="0,-4" Focusable="True">
        <my:MyUserControl.Resources>
            <Style x:Key="BorderStyle" TargetType="Border">
                <Setter Property="Background" Value="Blue"/>
                <Setter Property="BorderBrush" Value="Blue"/>
                <Style.Triggers>
                    <DataTrigger Binding="{Binding RelativeSource={RelativeSource 
                     AncestorType={x:Type my:GanttBar}}, Path=IsKeyboardFocusWithin}" 
                     Value="True">
                        <Setter Property="Background" Value="{StaticResource 
                        SelectedGanttBarBackGroundBrush}"/>
                        <Setter Property="BorderBrush" Value="{StaticResource 
                        SelectedGanttBarBorderBrush}"/>
                    </DataTrigger>
                </Style.Triggers>
            </Style>
        </my:MyUserControl.Resources>
        <Grid>
            <Grid.RowDefinitions>
                <RowDefinition Height="2*" />
                <RowDefinition Height="3*" />
                <RowDefinition Height="2*" />
            </Grid.RowDefinitions>
            <Label FontSize="8.5" HorizontalAlignment="Left"
            VerticalAlignment="Bottom" Margin="4,0,0,0" Foreground="Green" />
            <Border Grid.Row="1" CornerRadius="5" BorderThickness="1.5" Style="
            {StaticResource BorderStyle}" FocusVisualStyle="{StaticResource 
             SelectedBorderStyle}" Focusable="True" >
                <Label FontSize="10" HorizontalAlignment="Center" FontWeight="Bold" 
                 VerticalAlignment="Top" Foreground="White" Margin="0,2,0,0" />
            </Border>
            <Label HorizontalAlignment="Right" FontSize="8.5" Grid.Row="2" 
            VerticalAlignment="Top" Margin="0,0,4,0" Foreground="Red" />
        </Grid>
    </my:MyUserControl>

当我的UserControl 获得焦点时，我试图让嵌入边框的颜色改变颜色，但我无法终生弄清楚当我单击控件时实际获得焦点的是什么。我已经尝试为每个控件使用GotFocus 事件，一旦程序运行，什么都不会触发。

Answer 1

在属性 IsKeyboardFocusWithin 上使用 DataTrigger。我不确定确切的语法，但它应该看起来像这样：

<Style TargetType="{x:Type Border}">
    <Setter Property="BorderBrush" Value="Red" />
    <Style.Triggers>

        <!-- Will change Border color when KeyboardFocus inside Border -->
        <Trigger Property="IsKeyboardFocusWithin" Value="True">
            <Setter Property="BorderBrush" Value="Green" />
        </Trigger>

        <!-- Will change Border color when UserControl contains KeyboardFocus -->
        <DataTrigger Binding="{Binding RelativeSource={RelativeSource 
            AncestorType={x:Type local:MyUserControl}}, 
            Path=IsKeyboardFocusWithin}" Value="True">
            <Setter Property="BorderBrush" Value="Blue" />
        </DataTrigger>

    </Style.Triggers>
</Style>