WinUI3：如何修改RichTextBlock内HyperLink的PointerOver状态画笔

问题原因 #

HyperLink的默认样式中，PointerOver状态的前景色绑定了系统主题资源HyperlinkForegroundPointerOver，直接在RichTextBlock的Resources中覆盖该资源无法生效，是因为资源查找优先级规则：系统主题资源会优先于父容器的自定义资源被加载。

解决方案1：在HyperLink自身Resources中覆盖主题资源 #

将自定义的HyperlinkForegroundPointerOver画笔放在HyperLink的Resources中，确保HyperLink在查找资源时优先使用自定义值：

<Grid Margin="20" Width="200">
    <RichTextBlock x:Name="SelectCustomerWrapPanel" VerticalAlignment="Top" Grid.Column="1" FocusVisualSecondaryBrush="{ThemeResource SystemAccentColor}" 
                   FocusVisualPrimaryBrush="{ThemeResource SystemAccentColor}" TextWrapping="Wrap" 
                   LineHeight="20" Margin="0,0,16,0" HorizontalAlignment="Left" Foreground="Orange">
        <Paragraph>
            <Run Text="Attention!" Foreground="Red"/>
            <Run Text="You are in a wrapped content for checking the pointerover behavior" Foreground="Lavender"/>
            <Hyperlink Foreground="Orange" UnderlineStyle="Single" x:Name="ActionBanner" IsTabStop="True">
                <!-- 覆盖HyperLink悬停状态的前景色资源 -->
                <Hyperlink.Resources>
                    <SolidColorBrush x:Key="HyperlinkForegroundPointerOver" Color="Black"/>
                </Hyperlink.Resources>
                <Run Text="Hover this then it should change to black but it will set the accent color"/>
            </Hyperlink>
        </Paragraph>
    </RichTextBlock>
</Grid>

解决方案2：重写HyperLink的ControlTemplate #

完全自定义HyperLink的样式，直接指定PointerOver状态的前景色，这种方式更灵活，可同时修改其他交互状态的样式：

<Grid Margin="20" Width="200">
    <RichTextBlock x:Name="SelectCustomerWrapPanel" VerticalAlignment="Top" Grid.Column="1" FocusVisualSecondaryBrush="{ThemeResource SystemAccentColor}" 
                   FocusVisualPrimaryBrush="{ThemeResource SystemAccentColor}" TextWrapping="Wrap" 
                   LineHeight="20" Margin="0,0,16,0" HorizontalAlignment="Left" Foreground="Orange">
        <RichTextBlock.Resources>
            <!-- 自定义HyperLink样式 -->
            <Style TargetType="Hyperlink">
                <Setter Property="Foreground" Value="Orange"/>
                <Setter Property="UnderlineStyle" Value="Single"/>
                <Setter Property="IsTabStop" Value="True"/>
                <Setter Property="Template">
                    <Setter.Value>
                        <ControlTemplate TargetType="Hyperlink">
                            <TextBlock x:Name="TextElement"
                                       Text="{TemplateBinding Content}"
                                       Foreground="{TemplateBinding Foreground}"
                                       UnderlineStyle="{TemplateBinding UnderlineStyle}"/>
                            <ControlTemplate.Triggers>
                                <!-- 鼠标悬停状态 -->
                                <Trigger Property="IsPointerOver" Value="True">
                                    <Setter TargetName="TextElement" Property="Foreground" Value="Black"/>
                                </Trigger>
                                <!-- 点击按压状态（可选） -->
                                <Trigger Property="IsPressed" Value="True">
                                    <Setter TargetName="TextElement" Property="Foreground" Value="DarkGray"/>
                                </Trigger>
                                <!-- 获得焦点状态（可选） -->
                                <Trigger Property="IsFocused" Value="True">
                                    <Setter TargetName="TextElement" Property="Foreground" Value="Black"/>
                                </Trigger>
                            </ControlTemplate.Triggers>
                        </ControlTemplate>
                    </Setter.Value>
                </Setter>
            </Style>
        </RichTextBlock.Resources>
        <Paragraph>
            <Run Text="Attention!" Foreground="Red"/>
            <Run Text="You are in a wrapped content for checking the pointerover behavior" Foreground="Lavender"/>
            <Hyperlink x:Name="ActionBanner">
                <Run Text="Hover this then it should change to black but it will set the accent color"/>
            </Hyperlink>
        </Paragraph>
    </RichTextBlock>
</Grid>

内容的提问来源于stack exchange，提问作者Akilan