要更改长度指示器的位置，您只需要更改参数 ib LengthIndicatorVisible 的可视状态（特别是 Translate 变换和边距的更改）：
这是使指示器显示在顶部的完整样式（只是我删除之前提到的代码的默认PhoneTextBox样式，检索默认样式的方法是在Visual Studio中进入Outline窗口，在PhoneTextBox上单击右键， -> 模板 -> 编辑副本）：
<Style x:Key="PhoneTextBoxStyleIndicatorOnTop" TargetType="toolkit:PhoneTextBox">
<Setter Property="FontFamily" Value="{StaticResource PhoneFontFamilyNormal}"/>
<Setter Property="FontSize" Value="{StaticResource PhoneFontSizeMediumLarge}"/>
<Setter Property="Background" Value="{StaticResource PhoneTextBoxBrush}"/>
<Setter Property="Foreground" Value="{StaticResource PhoneTextBoxForegroundBrush}"/>
<Setter Property="BorderBrush" Value="{StaticResource PhoneTextBoxBrush}"/>
<Setter Property="SelectionBackground" Value="{StaticResource PhoneAccentBrush}"/>
<Setter Property="SelectionForeground" Value="{StaticResource PhoneTextBoxSelectionForegroundBrush}"/>
<Setter Property="BorderThickness" Value="{StaticResource PhoneBorderThickness}"/>
<Setter Property="Padding" Value="{StaticResource PhoneBorderThickness}"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="toolkit:PhoneTextBox">
<Grid x:Name="RootGrid" Background="Transparent">
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="Normal"/>
<VisualState x:Name="Disabled">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility" Storyboard.TargetName="HintBorder">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Collapsed</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility" Storyboard.TargetName="TextBorder">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Visible</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="BorderBrush" Storyboard.TargetName="TextBorder">
<DiscreteObjectKeyFrame KeyTime="0" Value="Transparent"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Margin" Storyboard.TargetName="TextBorder">
<DiscreteObjectKeyFrame KeyTime="0" Value="0"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="HorizontalAlignment" Storyboard.TargetName="Text">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<HorizontalAlignment>Stretch</HorizontalAlignment>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="FocusStates">
<VisualState x:Name="Focused">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Background" Storyboard.TargetName="HintBorder">
<DiscreteObjectKeyFrame KeyTime="0" Value="white"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="BorderBrush" Storyboard.TargetName="HintBorder">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource PhoneTextBoxEditBorderBrush}"/>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Unfocused"/>
</VisualStateGroup>
<VisualStateGroup x:Name="LengthIndicatorStates">
<VisualState x:Name="LengthIndicatorVisible">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility" Storyboard.TargetName="LengthIndicator">
<DiscreteObjectKeyFrame KeyTime="0:0:0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Visible</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Margin" Storyboard.TargetName="RootGrid">
<DiscreteObjectKeyFrame KeyTime="0:0:0" Value="0, 27, 0, 0"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Opacity" Storyboard.TargetName="LengthIndicator">
<DiscreteObjectKeyFrame KeyTime="0:0:0" Value="0.6"/>
</ObjectAnimationUsingKeyFrames>
<DoubleAnimation Duration="0:0:0.350" To="-32" Storyboard.TargetProperty="(UIElement.RenderTransform).(TranslateTransform.Y)" Storyboard.TargetName="LengthIndicator">
<DoubleAnimation.EasingFunction>
<ExponentialEase Exponent="6"/>
</DoubleAnimation.EasingFunction>
</DoubleAnimation>
</Storyboard>
</VisualState>
<VisualState x:Name="LengthIndicatorHidden">
<Storyboard>
<DoubleAnimation Duration="0:0:0.350" To="0" Storyboard.TargetProperty="(UIElement.RenderTransform).(TranslateTransform.Y)" Storyboard.TargetName="LengthIndicator">
<DoubleAnimation.EasingFunction>
<ExponentialEase Exponent="6"/>
</DoubleAnimation.EasingFunction>
</DoubleAnimation>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Margin" Storyboard.TargetName="RootGrid">
<DiscreteObjectKeyFrame KeyTime="0:0:0" Value="0, 0, 0, 0"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Opacity" Storyboard.TargetName="LengthIndicator">
<DiscreteObjectKeyFrame KeyTime="0:0:0.350" Value="0"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility" Storyboard.TargetName="LengthIndicator">
<DiscreteObjectKeyFrame KeyTime="0:0:0.350">
<DiscreteObjectKeyFrame.Value>
<Visibility>Collapsed</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<Border x:Name="LengthIndicatorBorder">
<TextBlock x:Name="LengthIndicator" Foreground="{StaticResource PhoneContrastBackgroundBrush}" FontSize="{StaticResource PhoneFontSizeNormal}" HorizontalAlignment="Right" Margin="{StaticResource PhoneMargin}" Opacity="0" TextAlignment="Right" VerticalAlignment="Top">
<TextBlock.RenderTransform>
<TranslateTransform/>
</TextBlock.RenderTransform>
</TextBlock>
</Border>
<Border x:Name="HintBorder" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Margin="{StaticResource PhoneTouchTargetOverhang}">
<Grid>
<ContentControl x:Name="HintContent" Background="Transparent" Content="{TemplateBinding Hint}" HorizontalAlignment="Left" Margin="3,0,3,0" Style="{TemplateBinding HintStyle}" Visibility="{TemplateBinding ActualHintVisibility}" VerticalAlignment="Center"/>
<ContentControl x:Name="ContentElement" BorderThickness="0" HorizontalContentAlignment="Stretch" Margin="{StaticResource PhoneTextBoxInnerMargin}" Padding="{TemplateBinding Padding}" VerticalContentAlignment="Stretch"/>
</Grid>
</Border>
<Border x:Name="TextBorder" BorderBrush="{StaticResource PhoneDisabledBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="Transparent" Margin="{StaticResource PhoneTouchTargetOverhang}" Visibility="Collapsed">
<TextBox x:Name="Text" Foreground="{StaticResource PhoneDisabledBrush}" FontWeight="{TemplateBinding FontWeight}" FontStyle="{TemplateBinding FontStyle}" FontSize="{TemplateBinding FontSize}" FontFamily="{TemplateBinding FontFamily}" HorizontalAlignment="Left" SelectionForeground="{TemplateBinding SelectionForeground}" SelectionBackground="{TemplateBinding SelectionBackground}" TextAlignment="{TemplateBinding TextAlignment}" TextWrapping="{TemplateBinding TextWrapping}" Text="{TemplateBinding Text}"/>
</Border>
<Border x:Name="ActionIconBorder" Background="Transparent" HorizontalAlignment="Right" Height="72" VerticalAlignment="Bottom" Width="84">
<Image x:Name="ActionIcon" Height="26" Source="{TemplateBinding ActionIcon}" Width="26"/>
</Border>
<TextBlock x:Name="MeasurementTextBlock" FontWeight="{TemplateBinding FontWeight}" FontStyle="{TemplateBinding FontStyle}" FontStretch="{TemplateBinding FontStretch}" FontSize="{TemplateBinding FontSize}" FontFamily="{TemplateBinding FontFamily}" IsHitTestVisible="False" Margin="8" Opacity="0" TextAlignment="{TemplateBinding TextAlignment}" TextWrapping="{TemplateBinding TextWrapping}" Text="{TemplateBinding Text}"/>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
只需在您的控件上设置样式：
<toolkit:PhoneTextBox LengthIndicatorVisible="True" DisplayedMaxLength="10" Style="{StaticResource PhoneTextBoxStyleIndicatorOnTop}"/>