TextAlignment 用于水平对齐.TextBlock 本身不支持垂直对齐.

TextAlignment is for horizontal alignment. TextBlock itself doesn't suport vertical alignment.

我建议在它周围放一个边框，让边框做垂直对齐:

I suggest put a border around it and let border do vertical alignment:

<Border BorderBrush="{x:Null}" Height="50">
    <TextBlock Text="Your text" VerticalAlignment="Center"/>
</Border>

或者其他方式是在文本块中使用高度和设置填充.

Or other way would be using height and set padding within textblock.

用于WPF中的密码框:

<PasswordBox HorizontalContentAlignment="Center" VerticalContentAlignment="Center" />

对于Silverlight，您需要提取密码框的实际模板(使用混合它允许您编辑模板并复制该模板)，然后您可以更改成员(在类型为 Border 的 ContentElement 上)使用模板绑定，如:

For Silverlight you will need to extract the actual template of passwordbox (use blend it allows you to edit template and copy that) then you can change the members (on ContentElement which is of type Border) with template binding like:

HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"

您也可以在此获取模板msdn 链接.

对于Silverlight 中的passworbox 更新您的xaml 中的密码框样式，如下所示:

For passworbox in Silverlight update password box style in your xaml as this:

        <ControlTemplate x:Key="ValidationToolTipTemplate">
        <Grid x:Name="Root" Margin="5,0" RenderTransformOrigin="0,0" Opacity="0">
            <Grid.RenderTransform>
                <TranslateTransform x:Name="xform" X="-25"/>
            </Grid.RenderTransform>
            <VisualStateManager.VisualStateGroups>
                <VisualStateGroup Name="OpenStates">
                    <VisualStateGroup.Transitions>
                        <VisualTransition GeneratedDuration="0"/>
                        <VisualTransition To="Open" GeneratedDuration="0:0:0.2">
                            <Storyboard>
                                <DoubleAnimation Storyboard.TargetName="xform" Storyboard.TargetProperty="X" To="0" Duration="0:0:0.2">
                                    <DoubleAnimation.EasingFunction>
                                        <BackEase Amplitude=".3" EasingMode="EaseOut"/>
                                    </DoubleAnimation.EasingFunction>
                                </DoubleAnimation>
                                <DoubleAnimation Storyboard.TargetName="Root" Storyboard.TargetProperty="Opacity" To="1" Duration="0:0:0.2"/>
                            </Storyboard>
                        </VisualTransition>
                    </VisualStateGroup.Transitions>
                    <VisualState x:Name="Closed">
                        <Storyboard>
                            <DoubleAnimation Storyboard.TargetName="Root" Storyboard.TargetProperty="Opacity" To="0" Duration="0"/>
                        </Storyboard>
                    </VisualState>
                    <VisualState x:Name="Open">
                        <Storyboard>
                            <DoubleAnimation Storyboard.TargetName="xform" Storyboard.TargetProperty="X" To="0" Duration="0"/>
                            <DoubleAnimation Storyboard.TargetName="Root" Storyboard.TargetProperty="Opacity" To="1" Duration="0"/>
                        </Storyboard>
                    </VisualState>
                </VisualStateGroup>
            </VisualStateManager.VisualStateGroups>

            <Border Margin="4,4,-4,-4" Background="#052A2E31" CornerRadius="5"/>
            <Border Margin="3,3,-3,-3" Background="#152A2E31" CornerRadius="4"/>
            <Border Margin="2,2,-2,-2" Background="#252A2E31" CornerRadius="3"/>
            <Border Margin="1,1,-1,-1" Background="#352A2E31" CornerRadius="2"/>

            <Border Background="#FFDC000C" CornerRadius="2"/>
            <Border CornerRadius="2">
                <TextBlock 
              UseLayoutRounding="false" 
              Foreground="White" Margin="8,4,8,4" MaxWidth="250" TextWrapping="Wrap" Text="{Binding (Validation.Errors)[0].ErrorContent}"/>
            </Border>
        </Grid>
    </ControlTemplate>
    <Style TargetType="PasswordBox">
        <Setter Property="BorderThickness" Value="1" />
        <Setter Property="Background" Value="#FFFFFFFF" />
        <Setter Property="Foreground" Value="#FF000000" />
        <Setter Property="Padding" Value="2" />
        <Setter Property="BorderBrush">
            <Setter.Value>
                <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
                    <GradientStop Color="#FFA3AEB9" Offset="0"/>
                    <GradientStop Color="#FF8399A9" Offset="0.375"/>
                    <GradientStop Color="#FF718597" Offset="0.375"/>
                    <GradientStop Color="#FF617584" Offset="1"/>
                </LinearGradientBrush>
            </Setter.Value>
        </Setter>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="PasswordBox">
                    <Grid x:Name="RootElement">
                        <VisualStateManager.VisualStateGroups>
                            <VisualStateGroup x:Name="CommonStates">
                                <VisualState x:Name="Normal" />
                                <VisualState x:Name="MouseOver">
                                    <Storyboard>
                                        <ColorAnimation Storyboard.TargetName="MouseOverBorder" Storyboard.TargetProperty="(Border.BorderBrush).(SolidColorBrush.Color)" To="#FF99C1E2" Duration="0"/>
                                    </Storyboard>
                                </VisualState>
                                <VisualState x:Name="Disabled">
                                    <Storyboard>
                                        <DoubleAnimation Storyboard.TargetName="DisabledVisualElement" Storyboard.TargetProperty="Opacity" To="1" Duration="0"/>
                                    </Storyboard>
                                </VisualState>
                            </VisualStateGroup>
                            <VisualStateGroup x:Name="FocusStates">
                                <VisualState x:Name="Focused">
                                    <Storyboard>
                                        <DoubleAnimation Storyboard.TargetName="FocusVisualElement" Storyboard.TargetProperty="Opacity" To="1" Duration="0"/>
                                    </Storyboard>
                                </VisualState>
                                <VisualState x:Name="Unfocused">
                                    <Storyboard>
                                        <DoubleAnimation Storyboard.TargetName="FocusVisualElement" Storyboard.TargetProperty="Opacity" To="0" Duration="0"/>
                                    </Storyboard>
                                </VisualState>
                            </VisualStateGroup>
                            <VisualStateGroup x:Name="ValidationStates">
                                <VisualState x:Name="Valid"/>
                                <VisualState x:Name="InvalidUnfocused">
                                    <Storyboard>
                                        <ObjectAnimationUsingKeyFrames Storyboard.TargetName="ValidationErrorElement" Storyboard.TargetProperty="Visibility">
                                            <DiscreteObjectKeyFrame KeyTime="0" >
                                                <DiscreteObjectKeyFrame.Value>
                                                    <Visibility>Visible</Visibility>
                                                </DiscreteObjectKeyFrame.Value>
                                            </DiscreteObjectKeyFrame>
                                        </ObjectAnimationUsingKeyFrames>
                                    </Storyboard>
                                </VisualState>
                                <VisualState x:Name="InvalidFocused">
                                    <Storyboard>
                                        <ObjectAnimationUsingKeyFrames Storyboard.TargetName="ValidationErrorElement" Storyboard.TargetProperty="Visibility">
                                            <DiscreteObjectKeyFrame KeyTime="0" >
                                                <DiscreteObjectKeyFrame.Value>
                                                    <Visibility>Visible</Visibility>
                                                </DiscreteObjectKeyFrame.Value>
                                            </DiscreteObjectKeyFrame>
                                        </ObjectAnimationUsingKeyFrames>
                                        <ObjectAnimationUsingKeyFrames Storyboard.TargetName="validationTooltip" Storyboard.TargetProperty="IsOpen">
                                            <DiscreteObjectKeyFrame KeyTime="0" >
                                                <DiscreteObjectKeyFrame.Value>
                                                    <sys:Boolean>True</sys:Boolean>
                                                </DiscreteObjectKeyFrame.Value>
                                            </DiscreteObjectKeyFrame>
                                        </ObjectAnimationUsingKeyFrames>
                                    </Storyboard>
                                </VisualState>
                            </VisualStateGroup>
                        </VisualStateManager.VisualStateGroups>

                        <Border x:Name="Border" BorderThickness="{TemplateBinding BorderThickness}" CornerRadius="1" Opacity="1" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}">
                            <Border x:Name="MouseOverBorder" BorderThickness="1" BorderBrush="Transparent">
                                <Border x:Name="ContentElement" Margin="{TemplateBinding Padding}" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
                            </Border>
                        </Border>
                        <Border x:Name="DisabledVisualElement" Background="#A5F7F7F7" BorderBrush="#A5F7F7F7" BorderThickness="{TemplateBinding BorderThickness}" Opacity="0" IsHitTestVisible="False"/>
                        <Border x:Name="FocusVisualElement" BorderBrush="#FF6DBDD1" BorderThickness="{TemplateBinding BorderThickness}" Margin="1" Opacity="0" IsHitTestVisible="False"/>
                        <Border x:Name="ValidationErrorElement" BorderThickness="1" CornerRadius="1" BorderBrush="#FFDB000C" Visibility="Collapsed">
                            <ToolTipService.ToolTip>
                                <ToolTip x:Name="validationTooltip" Template="{StaticResource ValidationToolTipTemplate}" Placement="Right" 
                                       PlacementTarget="{Binding RelativeSource={RelativeSource TemplatedParent}}" 
                                       DataContext="{Binding RelativeSource={RelativeSource TemplatedParent}}">
                                    <ToolTip.Triggers>
                                        <EventTrigger RoutedEvent="Canvas.Loaded">
                                            <EventTrigger.Actions>
                                                <BeginStoryboard>
                                                    <Storyboard>
                                                        <ObjectAnimationUsingKeyFrames Storyboard.TargetName="validationTooltip" Storyboard.TargetProperty="IsHitTestVisible">
                                                            <DiscreteObjectKeyFrame KeyTime="0" >
                                                                <DiscreteObjectKeyFrame.Value>
                                                                    <sys:Boolean>true</sys:Boolean>
                                                                </DiscreteObjectKeyFrame.Value>
                                                            </DiscreteObjectKeyFrame>
                                                        </ObjectAnimationUsingKeyFrames>
                                                    </Storyboard>
                                                </BeginStoryboard>
                                            </EventTrigger.Actions>
                                        </EventTrigger>
                                    </ToolTip.Triggers>
                                </ToolTip>
                            </ToolTipService.ToolTip>
                            <Grid Width="12" Height="12" HorizontalAlignment="Right" Margin="1,-4,-4,0" VerticalAlignment="Top" Background="Transparent">
                                <Path Margin="1,3,0,0" Data="M 1,0 L6,0 A 2,2 90 0 1 8,2 L8,7 z" Fill="#FFDC000C"/>
                                <Path Margin="1,3,0,0" Data="M 0,0 L2,0 L 8,6 L8,8" Fill="#ffffff"/>
                            </Grid>
                        </Border>
                    </Grid>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

那么你的 PasswordBox 可以这样对齐:

Then your PasswordBox can have alignment as such:

<PasswordBox HorizontalContentAlignment="Center" VerticalContentAlignment="Center"/>