WPF TreeView自带自定义滚动条

放在TreeView.Resources中：

 <Style TargetType="ScrollBar">
<Setter Property="Stylus.IsPressAndHoldEnabled" Value="false"/>
<Setter Property="Stylus.IsFlicksEnabled" Value="false"/>
<Setter Property="Width" Value="12"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ScrollBar}">
<Grid x:Name="Bg" SnapsToDevicePixels="true">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<!-- 定义滚动条的各个部分，如按钮和轨道 -->
<RepeatButton Grid.Row="0" Style="{StaticResource ScrollBarButtonStyle}" Command="{x:Static ScrollBar.LineUpCommand}" >
<Image Source="/Image/UpperIcon.png"/>
</RepeatButton>
<Track x:Name="PART_Track" Grid.Row="1" IsDirectionReversed="true">
<Track.DecreaseRepeatButton>
<RepeatButton Command="{x:Static ScrollBar.PageUpCommand}" Style="{StaticResource ScrollBarPageButtonStyle}"/>
</Track.DecreaseRepeatButton>
<Track.Thumb>
<Thumb Style="{StaticResource ScrollBarThumbStyle}"/>
</Track.Thumb>
<Track.IncreaseRepeatButton>
<RepeatButton Command="{x:Static ScrollBar.PageDownCommand}" Style="{StaticResource ScrollBarPageButtonStyle}"/>
</Track.IncreaseRepeatButton>
</Track>
<RepeatButton Grid.Row="2" Style="{StaticResource ScrollBarButtonStyle}" Command="{x:Static ScrollBar.LineDownCommand}" >
<Image Source="/Image/BelowIcon.png"/>
</RepeatButton>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>

剩下的放上面资源中：

<!-- 按钮样式定义 -->
<Style x:Key="ScrollBarButtonStyle" TargetType="{x:Type RepeatButton}">
<Setter Property="BorderThickness" Value="0"/>
</Style>
<!-- 页面按钮样式定义 -->
<Style x:Key="ScrollBarPageButtonStyle" TargetType="{x:Type RepeatButton}">
<Setter Property="BorderThickness" Value="0"/>
<Setter Property="Background" Value="Transparent"/>
</Style>
<!-- 拇指样式定义 -->
<Style x:Key="ScrollBarThumbStyle" TargetType="{x:Type Thumb}">
<Setter Property="Background" Value="LightGray"/>
<Setter Property="Width" Value="12"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type Thumb}">
<Border Background="{TemplateBinding Background}" CornerRadius="6">
<ContentPresenter HorizontalAlignment="Center" VerticalAlignment="Center" />
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>

最后记得给TreeView设置高度，不然滚动条出不来