通过覆盖或样式设置使 ScrollViewer 的 ScrollBar 始终可见

我试图使 ScrollViewer 的 ScrollBar 始终可见，这样它不仅在我尝试滚动文本视图时才出现，这样用户就知道还有更多内容可以查看。 起初，出于某种原因，我认为我只需要更改需要画笔覆盖的颜色，但实际上，ScrollBar 正在淡入和淡出，因此 ScrollViewer 或 ScrollBar 的模板需要更改。

我找到了刚刚放置在 App.Resources 部分中的 ScrollViewer 模板，但我不知道如何编辑它，以便 ScrollBar 始终可见：

<Style TargetType="ScrollViewer">
    <Setter Property="HorizontalScrollMode" Value="Enabled" />
    <Setter Property="VerticalScrollMode" Value="Enabled" />
    <Setter Property="IsHorizontalRailEnabled" Value="True" />
    <Setter Property="IsVerticalRailEnabled" Value="True" />
    <Setter Property="IsTabStop" Value="False" />
    <Setter Property="ZoomMode" Value="Enabled" />
    <Setter Property="HorizontalContentAlignment" Value="Left"/>
    <Setter Property="VerticalContentAlignment" Value="Top"/>
    <Setter Property="VerticalScrollBarVisibility" Value="Visible"/>
    <Setter Property="Padding" Value="0"/>
    <Setter Property="BorderThickness" Value="0"/>
    <Setter Property="BorderBrush" Value="Transparent"/>
    <Setter Property="Background" Value="Transparent"/>
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="ScrollViewer">
                <Border BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}">
                    <VisualStateManager.VisualStateGroups>
                        <VisualStateGroup x:Name="ScrollingIndicatorStates">
                            <VisualStateGroup.Transitions>
                                <VisualTransition From="MouseIndicator" To="NoIndicator">
                                    <Storyboard>
                                        <FadeOutThemeAnimation TargetName="ScrollBarSeparator" BeginTime="0:0:3" />
                                        <ObjectAnimationUsingKeyFrames Storyboard.TargetName="VerticalScrollBar"
                                                                   Storyboard.TargetProperty="IndicatorMode">
                                            <DiscreteObjectKeyFrame KeyTime="0:0:3">
                                                <DiscreteObjectKeyFrame.Value>
                                                    <ScrollingIndicatorMode>None</ScrollingIndicatorMode>
                                                </DiscreteObjectKeyFrame.Value>
                                            </DiscreteObjectKeyFrame>
                                        </ObjectAnimationUsingKeyFrames>
                                        <ObjectAnimationUsingKeyFrames Storyboard.TargetName="HorizontalScrollBar"
                                                                   Storyboard.TargetProperty="IndicatorMode">
                                            <DiscreteObjectKeyFrame KeyTime="0:0:3">
                                                <DiscreteObjectKeyFrame.Value>
                                                    <ScrollingIndicatorMode>None</ScrollingIndicatorMode>
                                                </DiscreteObjectKeyFrame.Value>
                                            </DiscreteObjectKeyFrame>
                                        </ObjectAnimationUsingKeyFrames>
                                    </Storyboard>
                                </VisualTransition>
                                <VisualTransition From="TouchIndicator" To="NoIndicator">
                                    <Storyboard>
                                        <FadeOutThemeAnimation TargetName="ScrollBarSeparator" />
                                        <ObjectAnimationUsingKeyFrames Storyboard.TargetName="VerticalScrollBar"
                                                                   Storyboard.TargetProperty="IndicatorMode">
                                            <DiscreteObjectKeyFrame KeyTime="0:0:0.5">
                                                <DiscreteObjectKeyFrame.Value>
                                                    <ScrollingIndicatorMode>None</ScrollingIndicatorMode>
                                                </DiscreteObjectKeyFrame.Value>
                                            </DiscreteObjectKeyFrame>
                                        </ObjectAnimationUsingKeyFrames>
                                        <ObjectAnimationUsingKeyFrames Storyboard.TargetName="HorizontalScrollBar"
                                                                   Storyboard.TargetProperty="IndicatorMode">
                                            <DiscreteObjectKeyFrame KeyTime="0:0:0.5">
                                                <DiscreteObjectKeyFrame.Value>
                                                    <ScrollingIndicatorMode>None</ScrollingIndicatorMode>
                                                </DiscreteObjectKeyFrame.Value>
                                            </DiscreteObjectKeyFrame>
                                        </ObjectAnimationUsingKeyFrames>
                                    </Storyboard>
                                </VisualTransition>
                            </VisualStateGroup.Transitions>

                            <VisualState x:Name="NoIndicator">
                                <Storyboard>
                                    <FadeOutThemeAnimation TargetName="ScrollBarSeparator" />
                                </Storyboard>
                            </VisualState>
                            <VisualState x:Name="TouchIndicator">
                                <Storyboard>
                                                                            <FadeInThemeAnimation TargetName="ScrollBarSeparator" />

                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="VerticalScrollBar"
                                                               Storyboard.TargetProperty="IndicatorMode"
                                                               Duration="0">
                                        <DiscreteObjectKeyFrame KeyTime="0">
                                            <DiscreteObjectKeyFrame.Value>
                                                <ScrollingIndicatorMode>TouchIndicator</ScrollingIndicatorMode>
                                            </DiscreteObjectKeyFrame.Value>
                                        </DiscreteObjectKeyFrame>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="HorizontalScrollBar"
                                                               Storyboard.TargetProperty="IndicatorMode"
                                                               Duration="0">
                                        <DiscreteObjectKeyFrame KeyTime="0">
                                            <DiscreteObjectKeyFrame.Value>
                                                <ScrollingIndicatorMode>TouchIndicator</ScrollingIndicatorMode>
                                            </DiscreteObjectKeyFrame.Value>
                                        </DiscreteObjectKeyFrame>
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                            <VisualState x:Name="MouseIndicator">
                                <Storyboard>
                                    <FadeInThemeAnimation TargetName="ScrollBarSeparator" />
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="VerticalScrollBar"
                                                               Storyboard.TargetProperty="IndicatorMode"
                                                               Duration="0">
                                        <DiscreteObjectKeyFrame KeyTime="0">
                                            <DiscreteObjectKeyFrame.Value>
                                                <ScrollingIndicatorMode>MouseIndicator</ScrollingIndicatorMode>
                                            </DiscreteObjectKeyFrame.Value>
                                        </DiscreteObjectKeyFrame>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="HorizontalScrollBar"
                                                               Storyboard.TargetProperty="IndicatorMode"
                                                               Duration="0">
                                        <DiscreteObjectKeyFrame KeyTime="0">
                                            <DiscreteObjectKeyFrame.Value>
                                                <ScrollingIndicatorMode>MouseIndicator</ScrollingIndicatorMode>
                                            </DiscreteObjectKeyFrame.Value>
                                        </DiscreteObjectKeyFrame>
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                        </VisualStateGroup>
                    </VisualStateManager.VisualStateGroups>
                    <Grid Background="{TemplateBinding Background}">
                        <Grid.ColumnDefinitions>
                            <ColumnDefinition Width="*"/>
                            <ColumnDefinition Width="Auto"/>
                        </Grid.ColumnDefinitions>
                        <Grid.RowDefinitions>
                            <RowDefinition Height="*"/>
                            <RowDefinition Height="Auto"/>
                        </Grid.RowDefinitions>
                        <ScrollContentPresenter x:Name="ScrollContentPresenter"
                                            Grid.RowSpan="2"
                                            Grid.ColumnSpan="2"
                                            ContentTemplate="{TemplateBinding ContentTemplate}"
                                            Margin="{TemplateBinding Padding}" />
                        <ScrollBar x:Name="VerticalScrollBar"
                               Grid.Column="1"
                               IsTabStop="False"
                               Maximum="{TemplateBinding ScrollableHeight}"
                               Orientation="Vertical"
                               Visibility="{TemplateBinding ComputedVerticalScrollBarVisibility}"
                               Value="{TemplateBinding VerticalOffset}"
                               ViewportSize="{TemplateBinding ViewportHeight}"
                               HorizontalAlignment="Right"/>
                        <ScrollBar x:Name="HorizontalScrollBar"
                               IsTabStop="False"
                               Maximum="{TemplateBinding ScrollableWidth}"
                               Orientation="Horizontal"
                               Grid.Row="1"
                               Visibility="{TemplateBinding ComputedHorizontalScrollBarVisibility}"
                               Value="{TemplateBinding HorizontalOffset}"
                               ViewportSize="{TemplateBinding ViewportWidth}" />
                        <!-- Change the opacity below, to zero. otherwise, the right and bottom border end up showing up as a single pixel lit on the screen even if the scroll is disabled. -->
                        <Border x:Name="ScrollBarSeparator"
                            Grid.Row="1"
                            Grid.Column="1"
                            Opacity="0"
                            BorderThickness="0,0,1,1"
                            Background="{StaticResource ScrollBarTrackBackgroundThemeBrush}"
                            BorderBrush="{StaticResource ScrollBarTrackBorderThemeBrush}" />
                    </Grid>
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

我尝试删除代码的各个部分，但结果，滚动条完全消失了。

你为什么不直接设置VerticalScrollBarVisibility和/或HorizontalScrollBarVisibility你的实例的ScrollViewer to Visible，而不是从样式中删除褪色行为？

<ScrollViewer VerticalScrollBarVisibility="Visible">
     <!-- ScrollViewer Content -->
</ScrollViewer>

评论后编辑：

我想我想出了一个“解决方案”。我不确定这是否是实现此目标的最佳方法，但它似乎给出了您想要的结果。

为以下内容创建自定义样式ScrollViewer，然后为垂直/水平制作一个ScrollBar本身（使用 Blend，我猜你之前就是这样做的）。 获得默认样式的副本后，编辑以下行：

<VisualState x:Name="NoIndicator">
    <Storyboard>
        <FadeOutThemeAnimation BeginTime="0" TargetName="HorizontalPanningRoot"/>
        <FadeOutThemeAnimation BeginTime="0" TargetName="VerticalPanningRoot"/>
        <Fade**In**ThemeAnimation BeginTime="0" TargetName="HorizontalRoot"/>
        <Fade**In**ThemeAnimation BeginTime="0" TargetName="VerticalRoot"/>
    </Storyboard>
</VisualState>

我的猜测是，这确实导致了ScrollBar当不与其交互时淡入，这意味着它将始终可见。

这是相关的 ScrollViewer XAML（我无法将整个内容放入答案中）。请注意，ScrollViewer 设置为使用我的自定义样式ScrollViewerStyle1，然后在该样式中VerticalScrollBar设置为我的ScrollBar定制风格ScrollBarCustomStyle1，其中NoIndicator VisualState被修改。如果需要，您可以对水平滚动条执行相同的操作。

滚动查看器风格：

<ScrollContentPresenter x:Name="ScrollContentPresenter" Grid.ColumnSpan="2" ContentTemplate="{TemplateBinding ContentTemplate}" Margin="{TemplateBinding Padding}" Grid.RowSpan="2"/>
<ScrollBar x:Name="VerticalScrollBar" Grid.Column="1" HorizontalAlignment="Right" IsTabStop="False" Maximum="{TemplateBinding ScrollableHeight}" Orientation="Vertical" Visibility="{TemplateBinding ComputedVerticalScrollBarVisibility}" Value="{TemplateBinding VerticalOffset}" ViewportSize="{TemplateBinding ViewportHeight}" Style="{StaticResource ScrollBarStyle1}"/>
<ScrollBar x:Name="HorizontalScrollBar" IsTabStop="False" Maximum="{TemplateBinding ScrollableWidth}" Orientation="Horizontal" Grid.Row="1" Visibility="{TemplateBinding ComputedHorizontalScrollBarVisibility}" Value="{TemplateBinding HorizontalOffset}" ViewportSize="{TemplateBinding ViewportWidth}"/>
<Border x:Name="ScrollBarSeparator" BorderBrush="{ThemeResource ScrollBarTrackBorderThemeBrush}" BorderThickness="0,0,1,1" Background="{ThemeResource ScrollBarTrackBackgroundThemeBrush}" Grid.Column="1" Grid.Row="1"/>