如何修改禁用状态下UWP ComboBox的前景色？

嗨，这个问题我之前做项目的时候也碰到过，默认的ComboBox禁用状态前景色确实淡得离谱，给你几个在XAML里就能轻松解决的方案：

如果不想折腾复杂的模板，直接给ComboBox加个Style触发器就行，代码简洁还能快速生效：

<ComboBox>
    <ComboBox.Style>
        <Style TargetType="ComboBox">
            <Style.Triggers>
                <!-- 当ComboBox禁用时，设置你想要的前景色 -->
                <Trigger Property="IsEnabled" Value="False">
                    <Setter Property="Foreground" Value="#FF333333"/>
                    <!-- 要是觉得背景也需要调整，也可以加这行 -->
                    <!-- <Setter Property="Background" Value="#FFEEEEEE"/> -->
                </Trigger>
            </Style.Triggers>
        </Style>
    </ComboBox.Style>
</ComboBox>

不过要注意，如果你用的是WPF自带的一些主题（比如Aero），这个触发器可能会被控件模板里的默认样式覆盖，这时候就需要用下面的方法了。

如果上面的方法不生效，那就直接重写ComboBox的ControlTemplate，精准控制禁用状态的外观，虽然代码长一点，但完全可控：

<ComboBox>
    <ComboBox.Style>
        <Style TargetType="ComboBox">
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="ComboBox">
                        <Grid x:Name="templateRoot" SnapsToDevicePixels="True">
                            <Grid.ColumnDefinitions>
                                <ColumnDefinition Width="*"/>
                                <ColumnDefinition MinWidth="{DynamicResource {x:Static SystemParameters.VerticalScrollBarWidthKey}}" Width="0"/>
                            </Grid.ColumnDefinitions>
                            <Popup x:Name="PART_Popup" AllowsTransparency="True" Grid.ColumnSpan="2" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" Margin="1" PopupAnimation="{DynamicResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
                                <Themes:SystemDropShadowChrome x:Name="shadow" Color="Transparent" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{Binding ActualWidth, ElementName=templateRoot}">
                                    <Border x:Name="dropDownBorder" BorderBrush="{DynamicResource {x:Static SystemColors.WindowFrameBrushKey}}" BorderThickness="1" Background="{DynamicResource {x:Static SystemColors.WindowBrushKey}}">
                                        <ScrollViewer x:Name="DropDownScrollViewer">
                                            <Grid x:Name="grid" RenderOptions.ClearTypeHint="Enabled">
                                                <Canvas x:Name="canvas" HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
                                                    <Rectangle x:Name="opaqueRect" Fill="{Binding Background, ElementName=dropDownBorder}" Height="{Binding ActualHeight, ElementName=dropDownBorder}" Width="{Binding ActualWidth, ElementName=dropDownBorder}"/>
                                                </Canvas>
                                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Contained" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                                            </Grid>
                                        </ScrollViewer>
                                    </Border>
                                </Themes:SystemDropShadowChrome>
                            </Popup>
                            <ToggleButton x:Name="toggleButton" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Grid.ColumnSpan="2" IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}">
                                <ToggleButton.Style>
                                    <Style TargetType="ToggleButton">
                                        <Setter Property="OverridesDefaultStyle" Value="True"/>
                                        <Setter Property="IsTabStop" Value="False"/>
                                        <Setter Property="Focusable" Value="False"/>
                                        <Setter Property="ClickMode" Value="Press"/>
                                        <Setter Property="Template">
                                            <Setter.Value>
                                                <ControlTemplate TargetType="ToggleButton">
                                                    <Border x:Name="templateRoot" BorderBrush="#FFACACAC" BorderThickness="{TemplateBinding BorderThickness}" Background="#FFEBEBEB" SnapsToDevicePixels="True">
                                                        <Border x:Name="splitBorder" BorderBrush="Transparent" BorderThickness="1" HorizontalAlignment="Right" Margin="0" SnapsToDevicePixels="True" Width="{DynamicResource {x:Static SystemParameters.VerticalScrollBarWidthKey}}">
                                                            <Path x:Name="arrow" Data="F1 M 0,0 L 2.667,2.66665 L 5.3334,0 L 5.3334,-1.78168 L 2.6667,0.88501 L0,-1.78168 L0,0 Z" Fill="#FF606060" HorizontalAlignment="Center" Margin="0" VerticalAlignment="Center"/>
                                                        </Border>
                                                    </Border>
                                                    <ControlTemplate.Triggers>
                                                        <Trigger Property="IsMouseOver" Value="True">
                                                            <Setter Property="Background" TargetName="templateRoot" Value="#FFF5F5F5"/>
                                                        </Trigger>
                                                        <Trigger Property="IsEnabled" Value="False">
                                                            <Setter Property="Background" TargetName="templateRoot" Value="#FFEBEBEB"/>
                                                            <Setter Property="BorderBrush" TargetName="templateRoot" Value="#FFADB2B5"/>
                                                            <Setter Property="Fill" TargetName="arrow" Value="#FF838383"/>
                                                        </Trigger>
                                                    </ControlTemplate.Triggers>
                                                </ControlTemplate>
                                            </Setter.Value>
                                        </Setter>
                                    </Style>
                                </ToggleButton.Style>
                            </ToggleButton>
                            <ContentPresenter x:Name="contentPresenter" ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}" Content="{TemplateBinding SelectionBoxItem}" ContentStringFormat="{TemplateBinding SelectionBoxItemStringFormat}" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" IsHitTestVisible="False" Margin="{TemplateBinding Padding}" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
                        </Grid>
                        <ControlTemplate.Triggers>
                            <Trigger Property="IsEnabled" Value="False">
                                <!-- 这里就是关键，修改禁用状态的前景色 -->
                                <Setter Property="Foreground" Value="#FF333333"/>
                            </Trigger>
                            <Trigger Property="HasDropShadow" SourceName="PART_Popup" Value="True">
                                <Setter Property="Margin" TargetName="shadow" Value="0,0,5,5"/>
                                <Setter Property="Color" TargetName="shadow" Value="#71000000"/>
                            </Trigger>
                            <Trigger Property="HasItems" Value="False">
                                <Setter Property="Height" TargetName="dropDownBorder" Value="95"/>
                            </Trigger>
                            <MultiTrigger>
                                <MultiTrigger.Conditions>
                                    <Condition Property="IsGrouping" Value="True"/>
                                    <Condition Property="VirtualizingPanel.IsVirtualizingWhenGrouping" Value="False"/>
                                </MultiTrigger.Conditions>
                                <Setter Property="ScrollViewer.CanContentScroll" Value="False"/>
                            </MultiTrigger>
                            <Trigger Property="CanContentScroll" SourceName="DropDownScrollViewer" Value="False">
                                <Setter Property="Canvas.Top" TargetName="opaqueRect" Value="{Binding VerticalOffset, ElementName=DropDownScrollViewer}"/>
                                <Setter Property="Canvas.Left" TargetName="opaqueRect" Value="{Binding HorizontalOffset, ElementName=DropDownScrollViewer}"/>
                            </Trigger>
                        </ControlTemplate.Triggers>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>
    </ComboBox.Style>
</ComboBox>

核心就是在ControlTemplate.Triggers里找到IsEnabled=False的触发器，设置你想要的前景色值就行。

如果你希望整个应用里所有禁用的ComboBox都用这个前景色，可以重写系统资源，这样不用每个ComboBox都单独设置：

<!-- 在Window或者App的Resources里添加 -->
<Window.Resources>
    <Style TargetType="ComboBox" BasedOn="{StaticResource {x:Type ComboBox}}">
        <Style.Resources>
            <!-- 覆盖禁用状态的前景色资源 -->
            <SolidColorBrush x:Key="{x:Static SystemColors.DisabledForegroundBrushKey}" Color="#FF333333"/>
        </Style.Resources>
    </Style>
</Window.Resources>

这个方法会让当前窗口里所有的ComboBox禁用时都用这个前景色，要是想全局生效，就把这段代码放到App.xaml的Resources里。

你可以根据自己的需求选对应的方法，一般先试试方法1，不行再用方法2，需要全局修改就用方法3～

内容的提问来源于stack exchange，提问作者alisheikh