根据Microsoft 文档VerticalContentAlignment 不适用于文本框的默认模板。
为了解决这个问题,我们需要自己的风格。将绑定verticalalignment 添加到模板的verticalcontentalignment 解决了这个问题。
这是我从标准文本框样式更改的元素
<ScrollViewer x:Name="ContentElement" VerticalAlignment="{TemplateBinding VerticalContentAlignment}" Padding="{TemplateBinding Padding}" BorderThickness="0" IsTabStop="False"/>
这是我用来实现这一目标的完整风格
<Style x:Key="TextBoxWithVerticalContentAlignment" TargetType="TextBox">
<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="TextBox">
<Grid x:Name="RootElement">
<vsm:VisualStateManager.VisualStateGroups>
<vsm:VisualStateGroup x:Name="CommonStates">
<vsm:VisualState x:Name="Normal"/>
<vsm:VisualState x:Name="MouseOver">
<Storyboard>
<ColorAnimation Storyboard.TargetName="MouseOverBorder" Storyboard.TargetProperty="(Border.BorderBrush).(SolidColorBrush.Color)" To="#FF99C1E2" Duration="0"/>
</Storyboard>
</vsm:VisualState>
<vsm:VisualState x:Name="Disabled">
<Storyboard>
<DoubleAnimation Storyboard.TargetName="DisabledVisualElement" Storyboard.TargetProperty="Opacity" To="1" Duration="0"/>
</Storyboard>
</vsm:VisualState>
<vsm:VisualState x:Name="ReadOnly">
<Storyboard>
<DoubleAnimation Storyboard.TargetName="ReadOnlyVisualElement" Storyboard.TargetProperty="Opacity" To="1" Duration="0" />
</Storyboard>
</vsm:VisualState>
</vsm:VisualStateGroup>
<vsm:VisualStateGroup x:Name="FocusStates">
<vsm:VisualState x:Name="Focused">
<Storyboard>
<DoubleAnimation Storyboard.TargetName="FocusVisualElement" Storyboard.TargetProperty="Opacity" To="1" Duration="0"/>
</Storyboard>
</vsm:VisualState>
<vsm:VisualState x:Name="Unfocused">
<Storyboard>
<DoubleAnimation Storyboard.TargetName="FocusVisualElement" Storyboard.TargetProperty="Opacity" To="0" Duration="0"/>
</Storyboard>
</vsm:VisualState>
</vsm:VisualStateGroup>
<vsm:VisualStateGroup x:Name="ValidationStates">
<vsm:VisualState x:Name="Valid"/>
<vsm: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>
</vsm:VisualState>
<vsm: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>
</vsm:VisualState>
</vsm:VisualStateGroup>
</vsm:VisualStateManager.VisualStateGroups>
<Border x:Name="Border" BorderThickness="{TemplateBinding BorderThickness}" CornerRadius="1" Opacity="1" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}">
<Grid>
<Border x:Name="ReadOnlyVisualElement" Opacity="0" Background="#5EC9C9C9"/>
<Border x:Name="MouseOverBorder" Background="White" BorderThickness="1" BorderBrush="Transparent">
<ScrollViewer x:Name="ContentElement" VerticalAlignment="{TemplateBinding VerticalContentAlignment}" Padding="{TemplateBinding Padding}" BorderThickness="0" IsTabStop="False"/>
</Border>
</Grid>
</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>
从另一个问题获得了很多帮助