c# - UWP应用程序上的文本框底部边框不可见

简而言之，您需要为TextBox创建自定义样式。

步骤：转到“文档大纲->右键单击文本框->编辑模板->编辑副本”。

然后，找到<Border x:Name="BorderElement">这种样式的元素并设置所需的元素MinHeight。

<Page.Resources>
    <Style x:Key="TextBoxStyle1" TargetType="TextBox">
        ...
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="TextBox">
                    <Grid>
                        ...
                        <ContentPresenter x:Name="HeaderContentPresenter" ContentTemplate="{TemplateBinding HeaderTemplate}" Content="{TemplateBinding Header}" Grid.ColumnSpan="2" Grid.Column="0" FontWeight="Normal" Foreground="{ThemeResource TextControlHeaderForeground}" Margin="{StaticResource TextBoxTopHeaderMargin}" Grid.Row="0" TextWrapping="Wrap" VerticalAlignment="Top" Visibility="Collapsed" x:DeferLoadStrategy="Lazy" />
                        <Border x:Name="BorderElement" MinHeight="25" Background="{TemplateBinding Background}" BorderThickness="{TemplateBinding BorderThickness}" BorderBrush="{TemplateBinding BorderBrush}" CornerRadius="{TemplateBinding CornerRadius}" Grid.ColumnSpan="2" Grid.Column="0" Control.IsTemplateFocusTarget="True"  MinWidth="{ThemeResource TextControlThemeMinWidth}" Grid.RowSpan="1" Grid.Row="1" />
                        <ScrollViewer x:Name="ContentElement" AutomationProperties.AccessibilityView="Raw" Grid.Column="0" HorizontalScrollBarVisibility="{TemplateBinding ScrollViewer.HorizontalScrollBarVisibility}" HorizontalScrollMode="{TemplateBinding ScrollViewer.HorizontalScrollMode}" IsDeferredScrollingEnabled="{TemplateBinding ScrollViewer.IsDeferredScrollingEnabled}" IsHorizontalRailEnabled="{TemplateBinding ScrollViewer.IsHorizontalRailEnabled}" IsTabStop="False" IsVerticalRailEnabled="{TemplateBinding ScrollViewer.IsVerticalRailEnabled}" Margin="{TemplateBinding BorderThickness}" Padding="{TemplateBinding Padding}" Grid.Row="1" VerticalScrollMode="{TemplateBinding ScrollViewer.VerticalScrollMode}" VerticalScrollBarVisibility="{TemplateBinding ScrollViewer.VerticalScrollBarVisibility}" ZoomMode="Disabled" />
                        <TextBlock x:Name="PlaceholderTextContentPresenter" Grid.ColumnSpan="2" Grid.Column="0" Foreground="{Binding PlaceholderForeground, RelativeSource={RelativeSource Mode=TemplatedParent}, TargetNullValue={ThemeResource TextControlPlaceholderForeground}}" IsHitTestVisible="False" Margin="{TemplateBinding BorderThickness}" Padding="{TemplateBinding Padding}" Grid.Row="1" Text="{TemplateBinding PlaceholderText}" TextWrapping="{TemplateBinding TextWrapping}" TextAlignment="{TemplateBinding TextAlignment}" />
                        <Button x:Name="DeleteButton" AutomationProperties.AccessibilityView="Raw" BorderThickness="{TemplateBinding BorderThickness}" Grid.Column="1" FontSize="{TemplateBinding FontSize}" IsTabStop="False" MinWidth="34" Margin="{ThemeResource HelperButtonThemePadding}" Grid.Row="1" Style="{StaticResource DeleteButtonStyle}" VerticalAlignment="Stretch" Visibility="Collapsed" />
                        <ContentPresenter x:Name="DescriptionPresenter" AutomationProperties.AccessibilityView="Raw" Content="{TemplateBinding Description}" Grid.ColumnSpan="2" Grid.Column="0" Foreground="{ThemeResource SystemControlDescriptionTextForegroundBrush}" Grid.Row="2" x:Load="False" />
                    </Grid>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</Page.Resources>
<Grid>
    <TextBox Style="{StaticResource TextBoxStyle1}" Height="25"></TextBox>
</Grid>

请注意，我仅更改了它的MinHeight，如果在其中输入它，则会发现其文本显示不完整。如果要使其看起来更好。您需要做更多的定制。

请阅读教程：创建自定义样式和控件模板以获取更多信息。