如何在.NET MAUI中重写Windows平台TextBox默认样式并移除清除按钮

一、重写TextBox默认样式（覆盖悬停/聚焦效果） #

Windows平台的TextBox默认视觉状态（如悬停背景变化、聚焦底部边框）由内置Style定义，仅通过代码设置基础属性无法覆盖这些状态行为，需要自定义完整的控件模板来替换默认样式：

1. 在MAUI Windows项目的App.xaml（或新建ResourceDictionary并合并到App.xaml）中添加自定义TextBox样式：

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <Style x:Key="CustomTextBoxStyle" TargetType="TextBox">
        <Setter Property="Background" Value="Transparent"/>
        <Setter Property="BorderThickness" Value="0"/>
        <Setter Property="CornerRadius" Value="0"/>
        <Setter Property="Padding" Value="0"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="TextBox">
                    <Grid>
                        <Border x:Name="BorderElement"
                                Background="{TemplateBinding Background}"
                                BorderThickness="{TemplateBinding BorderThickness}"
                                BorderBrush="{TemplateBinding BorderBrush}"
                                CornerRadius="{TemplateBinding CornerRadius}">
                            <ScrollViewer x:Name="ContentElement"
                                          Padding="{TemplateBinding Padding}"
                                          HorizontalScrollMode="{TemplateBinding ScrollViewer.HorizontalScrollMode}"
                                          HorizontalScrollBarVisibility="{TemplateBinding ScrollViewer.HorizontalScrollBarVisibility}"
                                          VerticalScrollMode="{TemplateBinding ScrollViewer.VerticalScrollMode}"
                                          VerticalScrollBarVisibility="{TemplateBinding ScrollViewer.VerticalScrollBarVisibility}"
                                          IsHorizontalRailEnabled="{TemplateBinding ScrollViewer.IsHorizontalRailEnabled}"
                                          IsVerticalRailEnabled="{TemplateBinding ScrollViewer.IsVerticalRailEnabled}"
                                          ZoomMode="Disabled"
                                          AutomationProperties.AccessibilityView="Raw"/>
                        </Border>
                    </Grid>
                    <ControlTemplate.Triggers>
                        <!-- 覆盖悬停状态，取消背景变化 -->
                        <Trigger Property="IsPointerOver" Value="True">
                            <Setter TargetName="BorderElement" Property="Background" Value="Transparent"/>
                        </Trigger>
                        <!-- 覆盖聚焦状态，取消边框变化 -->
                        <Trigger Property="IsFocused" Value="True">
                            <Setter TargetName="BorderElement" Property="BorderBrush" Value="Transparent"/>
                        </Trigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</ResourceDictionary>

2. 在CustomEntryHandler的CreatePlatformView方法中应用自定义样式：

protected override TextBox CreatePlatformView()
{
    var nativeView = new TextBox();

    // 应用自定义样式
    nativeView.Style = (Microsoft.UI.Xaml.Style)Microsoft.UI.Xaml.Application.Current.Resources["CustomTextBoxStyle"];
    
    nativeView.Margin = new Microsoft.UI.Xaml.Thickness(0);
    nativeView.FocusVisualMargin = new Microsoft.UI.Xaml.Thickness(0);
    nativeView.ClearButtonVisibility = Microsoft.UI.Xaml.Controls.ClearButtonVisibility.Collapsed;

    return nativeView;
}

二、移除TextBox的Clear按钮 #

直接设置TextBox的ClearButtonVisibility属性为Collapsed即可，上述代码已包含该设置，单独实现只需添加：

nativeView.ClearButtonVisibility = Microsoft.UI.Xaml.Controls.ClearButtonVisibility.Collapsed;

说明 #

自定义ControlTemplate是彻底覆盖TextBox默认视觉行为的核心，通过这种方式可以完全消除默认的悬停、聚焦等状态效果，实现完全自定义的视觉表现。

内容的提问来源于stack exchange，提问作者tob