如何触发IsFocused上DatePickerTextBox在WPF

Question

我通过Validation.ErrorTemplate设置DataTrigger属性。模板包括我周围的Border和DatePicker第二Border里面一个TextBlock。

我想看到的第二Border时DatePickerTextBox IsFocused属性仅True。

下面我的代码迄今（它只是一个缩短版）：

<Style x:Key="CustomDatePickerStyle" TargetType="{x:Type DatePicker}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type DatePicker}">
                <Border Background="{DynamicResource Control.Background}" Padding="0" BorderThickness="0" CornerRadius="3">
                        <Button x:Name="PART_Button" Grid.Column="1" Foreground="{TemplateBinding Foreground}" Focusable="False" HorizontalAlignment="Left" Margin="3,0,3,0" Grid.Row="0" Template="{StaticResource DropDownButtonTemplate}" VerticalAlignment="Center" Width="20"/>
                        <DatePickerTextBox x:Name="PART_TextBox" Height="14" Margin="3 0 0 0" Grid.Column="0" Focusable="{TemplateBinding Focusable}" 
                                               HorizontalContentAlignment="Stretch" Grid.Row="0" VerticalContentAlignment="Center">
                            <DatePickerTextBox.Template>
                                <ControlTemplate TargetType="DatePickerTextBox">
                                    <Border x:Name="Border" BorderBrush="{TemplateBinding BorderBrush}" Background="{TemplateBinding Background}" CornerRadius="3" Opacity="1">
                                        <Grid x:Name="WatermarkContent" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}">
                                            <Border x:Name="ContentElement" BorderBrush="Red" BorderThickness="0"/>
                                            <ScrollViewer x:Name="PART_ContentHost" Background="{TemplateBinding Background}" HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}" VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"/>
                                            <Border x:Name="FocusVisual" BorderBrush="Red" CornerRadius="3" IsHitTestVisible="False" Opacity="0"/>
                                        </Grid>
                                    </Border>
                                </ControlTemplate>
                            </DatePickerTextBox.Template>
                        </DatePickerTextBox>
                    </Grid>
                </Border>
                <ControlTemplate.Triggers>
                    <DataTrigger Binding="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=IsReadOnly}" Value="false">
                        <Setter Property="Validation.ErrorTemplate">
                            <Setter.Value>
                                <ControlTemplate>
                                    <StackPanel>
                                        <Border BorderThickness="1" BorderBrush="Red" CornerRadius="3" HorizontalAlignment="Left">
                                            <AdornedElementPlaceholder x:Name="textBox"/>
                                        </Border>
                                        <Border Background="{DynamicResource Control.Validation.Background}" BorderBrush="{DynamicResource Control.Validation.Border}" BorderThickness="1" CornerRadius="3" >
                                            <TextBlock Text="{Binding [0].ErrorContent}" Padding="3 0 3 0" Foreground="{DynamicResource Control.Validation.Foreground}" Margin="1"/>
                                            <Border.Style>
                                                <Style>
                                                    <Setter Property="Border.Visibility" Value="Collapsed"></Setter>
                                                    <Style.Triggers>
                                                        <DataTrigger Binding="{Binding AdornedElement.(DatePicker.IsFocused), ElementName=textBox}" Value="True">
                                                            <Setter Property="Border.Visibility" Value="Visible"/>
                                                        </DataTrigger>
                                                    </Style.Triggers>
                                                </Style>
                                            </Border.Style>
                                        </Border>
                                    </StackPanel>
                                </ControlTemplate>
                            </Setter.Value>
                        </Setter>
                    </DataTrigger>
                </ControlTemplate.Triggers>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

我认为这是可能通过通过ElementName = PART_TextBox, Path=IsFocused访问，但我总是得到Error：PART_TextBox未找到

Answer 1

该DatePicker的也有IsKeyboardFocusWithin属性是真，如果焦点是在的DatePicker的文本框中。这帮助了，我有同样的问题。

<Style TargetType="DatePicker">
    <Style.Triggers>
        <Trigger Property="IsKeyboardFocusWithin" Value="True">
            <Setter Property="Background" Value="Green"/>
        </Trigger>
    </Style.Triggers>
</Style>