HandyControl/src/Avalonia/HandyControl_Avalonia/Themes/Styles/ScrollViewer.axaml

<ResourceDictionary xmlns="https://github.com/avaloniaui"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    x:ClassModifier="internal"
                    xmlns:hc="https://handyorg.github.io/handycontrol"
                    xmlns:converters="using:Avalonia.Controls.Converters">
    <ControlTheme x:Key="ScrollBarBaseRepeatButton"
                  TargetType="RepeatButton">
        <Setter Property="Background"
                Value="Transparent" />
        <Setter Property="Focusable"
                Value="false" />
        <Setter Property="IsTabStop"
                Value="false" />
        <Setter Property="Template">
            <ControlTemplate TargetType="RepeatButton">
                <Rectangle Fill="{TemplateBinding Background}"
                           Height="{TemplateBinding Height}"
                           Width="{TemplateBinding Width}" />
            </ControlTemplate>
        </Setter>
    </ControlTheme>

    <ControlTheme x:Key="ScrollBarBaseThumbVertical"
                  TargetType="Thumb">
        <Setter Property="Background"
                Value="{DynamicResource SecondaryTextBrush}" />
        <Setter Property="IsTabStop"
                Value="false" />
        <Setter Property="Template">
            <ControlTemplate>
                <Border Width="{TemplateBinding Width}"
                        Background="Transparent">
                    <Rectangle x:Name="rectangle"
                               RadiusX="1"
                               RadiusY="1"
                               HorizontalAlignment="Center"
                               Height="{TemplateBinding Height}"
                               Width="2"
                               Fill="{TemplateBinding Background}">
                        <Rectangle.Transitions>
                            <Transitions>
                                <DoubleTransition Property="Width"
                                                  Duration="0:0:0.1" />
                                <DoubleTransition Property="RadiusX"
                                                  Duration="0:0:0.1" />
                                <DoubleTransition Property="RadiusY"
                                                  Duration="0:0:0.1" />
                            </Transitions>
                        </Rectangle.Transitions>
                    </Rectangle>
                </Border>
            </ControlTemplate>
        </Setter>

        <Style Selector="^:pointerover /template/ Rectangle">
            <Setter Property="Width"
                    Value="8" />
            <Setter Property="RadiusX"
                    Value="4" />
            <Setter Property="RadiusY"
                    Value="4" />
        </Style>

        <Style Selector="^:pressed /template/ Rectangle">
            <Setter Property="Fill"
                    Value="{DynamicResource PrimaryTextBrush}" />
        </Style>
    </ControlTheme>

    <ControlTheme x:Key="ScrollBarBaseThumbHorizontal"
                  TargetType="Thumb">
        <Setter Property="Background"
                Value="{DynamicResource SecondaryTextBrush}" />
        <Setter Property="IsTabStop"
                Value="false" />
        <Setter Property="Template">
            <ControlTemplate>
                <Border Width="{TemplateBinding Height}"
                        Background="Transparent">
                    <Rectangle x:Name="rectangle"
                               RadiusX="1"
                               RadiusY="1"
                               VerticalAlignment="Center"
                               Height="2"
                               Width="{TemplateBinding Width}"
                               Fill="{TemplateBinding Background}">
                        <Rectangle.Transitions>
                            <Transitions>
                                <DoubleTransition Property="Height"
                                                  Duration="0:0:0.1" />
                                <DoubleTransition Property="RadiusX"
                                                  Duration="0:0:0.1" />
                                <DoubleTransition Property="RadiusY"
                                                  Duration="0:0:0.1" />
                            </Transitions>
                        </Rectangle.Transitions>
                    </Rectangle>
                </Border>
            </ControlTemplate>
        </Setter>

        <Style Selector="^:pointerover /template/ Rectangle">
            <Setter Property="Height"
                    Value="8" />
            <Setter Property="RadiusX"
                    Value="4" />
            <Setter Property="RadiusY"
                    Value="4" />
        </Style>

        <Style Selector="^:pressed /template/ Rectangle">
            <Setter Property="Fill"
                    Value="{DynamicResource PrimaryTextBrush}" />
        </Style>
    </ControlTheme>

    <ControlTheme x:Key="ScrollBarBaseStyle"
                  TargetType="ScrollBar">
        <Setter Property="Background"
                Value="Transparent" />
        <Setter Property="Focusable"
                Value="False" />
        <Setter Property="BorderThickness"
                Value="0" />
        <Setter Property="MinHeight"
                Value="8" />
        <Setter Property="MinWidth"
                Value="8" />
        <Setter Property="Transitions">
            <Transitions>
                <DoubleTransition Property="Opacity"
                                  Duration="0:0:0.1" />
            </Transitions>
        </Setter>

        <Style Selector="^:horizontal">
            <Setter Property="Template">
                <ControlTemplate>
                    <Panel>
                        <Border Background="{TemplateBinding Background}" />
                        <Track Maximum="{TemplateBinding Maximum}"
                               Minimum="{TemplateBinding Minimum}"
                               Orientation="{TemplateBinding Orientation}"
                               ViewportSize="{TemplateBinding ViewportSize}"
                               DeferThumbDrag="{TemplateBinding ScrollViewer.IsDeferredScrollingEnabled}"
                               Value="{TemplateBinding Value, Mode=TwoWay}">
                            <Track.DecreaseButton>
                                <RepeatButton Name="PART_PageUpButton"
                                              Theme="{StaticResource ScrollBarBaseRepeatButton}" />
                            </Track.DecreaseButton>
                            <Track.IncreaseButton>
                                <RepeatButton Name="PART_PageDownButton"
                                              Theme="{StaticResource ScrollBarBaseRepeatButton}" />
                            </Track.IncreaseButton>
                            <Thumb Theme="{StaticResource ScrollBarBaseThumbHorizontal}" />
                        </Track>
                    </Panel>
                </ControlTemplate>
            </Setter>
        </Style>

        <Style Selector="^:vertical">
            <Setter Property="Template">
                <ControlTemplate>
                    <Panel>
                        <Border Background="{TemplateBinding Background}" />
                        <Track IsDirectionReversed="True"
                               Maximum="{TemplateBinding Maximum}"
                               Minimum="{TemplateBinding Minimum}"
                               Orientation="{TemplateBinding Orientation}"
                               ViewportSize="{TemplateBinding ViewportSize}"
                               DeferThumbDrag="{TemplateBinding ScrollViewer.IsDeferredScrollingEnabled}"
                               Value="{TemplateBinding Value, Mode=TwoWay}">
                            <Track.DecreaseButton>
                                <RepeatButton Name="PART_PageUpButton"
                                              Theme="{StaticResource ScrollBarBaseRepeatButton}" />
                            </Track.DecreaseButton>
                            <Track.IncreaseButton>
                                <RepeatButton Name="PART_PageDownButton"
                                              Theme="{StaticResource ScrollBarBaseRepeatButton}" />
                            </Track.IncreaseButton>
                            <Thumb Theme="{StaticResource ScrollBarBaseThumbVertical}" />
                        </Track>
                    </Panel>
                </ControlTemplate>
            </Setter>
        </Style>
    </ControlTheme>

    <ControlTheme x:Key="ScrollViewerNativeBaseStyle"
                  TargetType="ScrollViewer">
        <Setter Property="Background"
                Value="Transparent" />
        <Setter Property="Template">
            <ControlTemplate>
                <Grid ColumnDefinitions="*,Auto"
                      RowDefinitions="*,Auto">
                    <ScrollContentPresenter Name="PART_ContentPresenter"
                                            Grid.RowSpan="2"
                                            Grid.ColumnSpan="2"
                                            Padding="{TemplateBinding Padding}"
                                            HorizontalSnapPointsType="{TemplateBinding HorizontalSnapPointsType}"
                                            VerticalSnapPointsType="{TemplateBinding VerticalSnapPointsType}"
                                            HorizontalSnapPointsAlignment="{TemplateBinding HorizontalSnapPointsAlignment}"
                                            VerticalSnapPointsAlignment="{TemplateBinding VerticalSnapPointsAlignment}"
                                            Background="{TemplateBinding Background}"
                                            ScrollViewer.IsScrollInertiaEnabled="{TemplateBinding IsScrollInertiaEnabled}">
                        <ScrollContentPresenter.GestureRecognizers>
                            <ScrollGestureRecognizer CanHorizontallyScroll="{Binding CanHorizontallyScroll, ElementName=PART_ContentPresenter}"
                                                     CanVerticallyScroll="{Binding CanVerticallyScroll, ElementName=PART_ContentPresenter}"
                                                     IsScrollInertiaEnabled="{Binding (ScrollViewer.IsScrollInertiaEnabled), ElementName=PART_ContentPresenter}" />
                        </ScrollContentPresenter.GestureRecognizers>
                    </ScrollContentPresenter>
                    <ScrollBar Name="PART_HorizontalScrollBar"
                               Grid.Row="1"
                               Grid.Column="0"
                               Opacity=".3"
                               Theme="{StaticResource ScrollBarBaseStyle}"
                               Orientation="Horizontal" />
                    <ScrollBar Name="PART_VerticalScrollBar"
                               Grid.Row="0"
                               Grid.Column="1"
                               Opacity="0"
                               Theme="{StaticResource ScrollBarBaseStyle}"
                               Orientation="Vertical" />
                </Grid>
            </ControlTemplate>
        </Setter>

        <Style Selector="^:pointerover /template/ ScrollBar">
            <Setter Property="Opacity"
                    Value=".8" />
        </Style>
    </ControlTheme>

    <ControlTheme x:Key="{x:Type ScrollViewer}"
                  BasedOn="{StaticResource ScrollViewerNativeBaseStyle}"
                  TargetType="ScrollViewer" />

    <ControlTheme x:Key="ScrollViewerUpDownRepeatButtonStyle"
                  BasedOn="{StaticResource RepeatButtonIcon}"
                  TargetType="RepeatButton">
        <Setter Property="HorizontalAlignment"
                Value="Stretch" />
        <Setter Property="Height"
                Value="10" />
        <Setter Property="Padding"
                Value="0,2" />
        <Setter Property="Foreground"
                Value="{DynamicResource PrimaryTextBrush}" />
    </ControlTheme>

    <ControlTheme x:Key="ScrollViewerUpDown"
                  TargetType="ScrollViewer">
        <Setter Property="VerticalScrollBarVisibility"
                Value="Auto" />
        <Setter Property="Focusable"
                Value="False" />
        <Setter Property="Template">
            <ControlTemplate>
                <DockPanel>
                    <RepeatButton Theme="{StaticResource ScrollViewerUpDownRepeatButtonStyle}"
                                  hc:IconElement.Geometry="{StaticResource UpGeometry}"
                                  Command="{Binding LineUp, RelativeSource={RelativeSource TemplatedParent}}"
                                  DockPanel.Dock="Top">
                        <RepeatButton.IsVisible>
                            <MultiBinding Converter="{x:Static converters:MenuScrollingVisibilityConverter.Instance}"
                                          ConverterParameter="0">
                                <Binding Path="VerticalScrollBarVisibility"
                                         RelativeSource="{RelativeSource TemplatedParent}" />
                                <Binding Path="Offset.Y"
                                         RelativeSource="{RelativeSource TemplatedParent}" />
                                <Binding Path="Extent.Height"
                                         RelativeSource="{RelativeSource TemplatedParent}" />
                                <Binding Path="Viewport.Height"
                                         RelativeSource="{RelativeSource TemplatedParent}" />
                            </MultiBinding>
                        </RepeatButton.IsVisible>
                    </RepeatButton>
                    <RepeatButton Theme="{StaticResource ScrollViewerUpDownRepeatButtonStyle}"
                                  hc:IconElement.Geometry="{StaticResource DownGeometry}"
                                  Command="{Binding LineDown, RelativeSource={RelativeSource TemplatedParent}}"
                                  DockPanel.Dock="Bottom">
                        <RepeatButton.IsVisible>
                            <MultiBinding Converter="{x:Static converters:MenuScrollingVisibilityConverter.Instance}"
                                          ConverterParameter="100">
                                <Binding Path="VerticalScrollBarVisibility"
                                         RelativeSource="{RelativeSource TemplatedParent}" />
                                <Binding Path="Offset.Y"
                                         RelativeSource="{RelativeSource TemplatedParent}" />
                                <Binding Path="Extent.Height"
                                         RelativeSource="{RelativeSource TemplatedParent}" />
                                <Binding Path="Viewport.Height"
                                         RelativeSource="{RelativeSource TemplatedParent}" />
                            </MultiBinding>
                        </RepeatButton.IsVisible>
                    </RepeatButton>
                    <ScrollContentPresenter Name="PART_ContentPresenter"
                                            Margin="{TemplateBinding Padding}" />
                </DockPanel>
            </ControlTemplate>
        </Setter>
    </ControlTheme>
</ResourceDictionary>