Customizing UWP Slider Thumb

Visual Studio WinUI XAML

6 years ago

The default UWP Slider control features a very simple rectangular thumb. Luckily enough, thanks to the customizability of XAML design you can replace the default thumb with a custom control to give your app a fresh and original look.

Custom thumb

Custom thumb
The default template of the `Slider` control contains a custom style for the `Thumb` control: 
<Style x:Key="SliderThumbStyle" TargetType="Thumb">
    <Setter Property="BorderThickness" Value="0"/>
    <Setter Property="Background" Value="{ThemeResource SliderThumbBackground}"/>
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="Thumb">
                <Border Background="{TemplateBinding Background}" BorderThickness="{TemplateBinding BorderThickness}" BorderBrush="{TemplateBinding BorderBrush}" CornerRadius="4"/>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

As we can see, the Thumb uses a Border with CornerRadius as its template. We can cut this template contents and replace it with anything else. A great replacement is an Image control:

<ControlTemplate TargetType="Thumb">
    <Image Source="/Assets/Thumb.png" />
</ControlTemplate>

Furthermore, if your icon is monochromatic, we might want to use BitmapIcon as this will allow your thumb to automatically take on the accent color of the OS.

<ControlTemplate TargetType="Thumb">
    <BitmapIcon UriSource="/Assets/Thumb.png" />
</ControlTemplate>

There is one more thing we need to do however. The default Slider template explicitly sets the Width and Height of the thumb to be quite small. Search for HorizontalThumb and VerticalThumb declarations in the template and update them with different dimensions that suit your icon more:

<Thumb x:Name="HorizontalThumb" ... Height="24" Width="24"/>

<Thumb x:Name="VerticalThumb" ... Height="24" Width="24"/>

Full style

<Style x:Key="CustomThumbSlider" TargetType="Slider">
    <Setter Property="Background" Value="{ThemeResource SliderTrackFill}"/>
    <Setter Property="BorderThickness" Value="{ThemeResource SliderBorderThemeThickness}"/>
    <Setter Property="Foreground" Value="{ThemeResource SliderTrackValueFill}"/>
    <Setter Property="FontFamily" Value="{ThemeResource ContentControlThemeFontFamily}"/>
    <Setter Property="FontSize" Value="{ThemeResource ControlContentThemeFontSize}"/>
    <Setter Property="ManipulationMode" Value="None"/>
    <Setter Property="UseSystemFocusVisuals" Value="True"/>
    <Setter Property="FocusVisualMargin" Value="-7,0,-7,0"/>
    <Setter Property="IsFocusEngagementEnabled" Value="True"/>
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="Slider">
                <Grid Margin="{TemplateBinding Padding}">
                    <Grid.Resources>
                        <Style x:Key="SliderThumbStyle" TargetType="Thumb">
                            <Setter Property="BorderThickness" Value="0"/>
                            <Setter Property="Background" Value="{ThemeResource SliderThumbBackground}"/>
                            <Setter Property="Template">
                                <Setter.Value>
                                    <ControlTemplate TargetType="Thumb">
                                        <Image Source="/Assets/Thumb.png" />
                                    </ControlTemplate>
                                </Setter.Value>
                            </Setter>
                        </Style>
                    </Grid.Resources>
                    <Grid.RowDefinitions>
                        <RowDefinition Height="Auto"/>
                        <RowDefinition Height="*"/>
                    </Grid.RowDefinitions>
                    <VisualStateManager.VisualStateGroups>
                        <VisualStateGroup x:Name="CommonStates">
                            <VisualState x:Name="Normal"/>
                            <VisualState x:Name="Pressed">
                                <Storyboard>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="HorizontalTrackRect" Storyboard.TargetProperty="Fill">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SliderTrackFillPressed}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="VerticalTrackRect" Storyboard.TargetProperty="Fill">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SliderTrackFillPressed}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="HorizontalThumb" Storyboard.TargetProperty="Background">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SliderThumbBackgroundPressed}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="VerticalThumb" Storyboard.TargetProperty="Background">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SliderThumbBackgroundPressed}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="SliderContainer" Storyboard.TargetProperty="Background">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SliderContainerBackgroundPressed}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="HorizontalDecreaseRect" Storyboard.TargetProperty="Fill">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SliderTrackValueFillPressed}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="VerticalDecreaseRect" Storyboard.TargetProperty="Fill">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SliderTrackValueFillPressed}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                            <VisualState x:Name="Disabled">
                                <Storyboard>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="HeaderContentPresenter" Storyboard.TargetProperty="Foreground">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SliderHeaderForegroundDisabled}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="HorizontalDecreaseRect" Storyboard.TargetProperty="Fill">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SliderTrackValueFillDisabled}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="HorizontalTrackRect" Storyboard.TargetProperty="Fill">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SliderTrackFillDisabled}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="VerticalDecreaseRect" Storyboard.TargetProperty="Fill">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SliderTrackValueFillDisabled}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="VerticalTrackRect" Storyboard.TargetProperty="Fill">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SliderTrackFillDisabled}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="HorizontalThumb" Storyboard.TargetProperty="Background">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SliderThumbBackgroundDisabled}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="VerticalThumb" Storyboard.TargetProperty="Background">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SliderThumbBackgroundDisabled}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="TopTickBar" Storyboard.TargetProperty="Fill">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SliderTickBarFillDisabled}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="BottomTickBar" Storyboard.TargetProperty="Fill">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SliderTickBarFillDisabled}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="LeftTickBar" Storyboard.TargetProperty="Fill">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SliderTickBarFillDisabled}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="RightTickBar" Storyboard.TargetProperty="Fill">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SliderTickBarFillDisabled}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="SliderContainer" Storyboard.TargetProperty="Background">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SliderContainerBackgroundDisabled}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                            <VisualState x:Name="PointerOver">
                                <Storyboard>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="HorizontalTrackRect" Storyboard.TargetProperty="Fill">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SliderTrackFillPointerOver}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="VerticalTrackRect" Storyboard.TargetProperty="Fill">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SliderTrackFillPointerOver}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="HorizontalThumb" Storyboard.TargetProperty="Background">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SliderThumbBackgroundPointerOver}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="VerticalThumb" Storyboard.TargetProperty="Background">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SliderThumbBackgroundPointerOver}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="SliderContainer" Storyboard.TargetProperty="Background">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SliderContainerBackgroundPointerOver}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="HorizontalDecreaseRect" Storyboard.TargetProperty="Fill">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SliderTrackValueFillPointerOver}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="VerticalDecreaseRect" Storyboard.TargetProperty="Fill">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SliderTrackValueFillPointerOver}"/>
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                        </VisualStateGroup>
                        <VisualStateGroup x:Name="FocusEngagementStates">
                            <VisualState x:Name="FocusDisengaged"/>
                            <VisualState x:Name="FocusEngagedHorizontal">
                                <Storyboard>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="SliderContainer" Storyboard.TargetProperty="(Control.IsTemplateFocusTarget)">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="False"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="HorizontalThumb" Storyboard.TargetProperty="(Control.IsTemplateFocusTarget)">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="True"/>
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                            <VisualState x:Name="FocusEngagedVertical">
                                <Storyboard>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="SliderContainer" Storyboard.TargetProperty="(Control.IsTemplateFocusTarget)">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="False"/>
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="VerticalThumb" Storyboard.TargetProperty="(Control.IsTemplateFocusTarget)">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="True"/>
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                        </VisualStateGroup>
                    </VisualStateManager.VisualStateGroups>
                    <ContentPresenter x:Name="HeaderContentPresenter" ContentTemplate="{TemplateBinding HeaderTemplate}" Content="{TemplateBinding Header}" FontWeight="{ThemeResource SliderHeaderThemeFontWeight}" Foreground="{ThemeResource SliderHeaderForeground}" Margin="{ThemeResource SliderHeaderThemeMargin}" TextWrapping="Wrap" Visibility="Collapsed" x:DeferLoadStrategy="Lazy"/>
                    <Grid x:Name="SliderContainer" Background="{ThemeResource SliderContainerBackground}" Control.IsTemplateFocusTarget="True" Grid.Row="1">
                        <Grid x:Name="HorizontalTemplate" MinHeight="44">
                            <Grid.ColumnDefinitions>
                                <ColumnDefinition Width="Auto"/>
                                <ColumnDefinition Width="Auto"/>
                                <ColumnDefinition Width="*"/>
                            </Grid.ColumnDefinitions>
                            <Grid.RowDefinitions>
                                <RowDefinition Height="18"/>
                                <RowDefinition Height="Auto"/>
                                <RowDefinition Height="18"/>
                            </Grid.RowDefinitions>
                            <Rectangle x:Name="HorizontalTrackRect" Grid.ColumnSpan="3" Fill="{TemplateBinding Background}" Height="{ThemeResource SliderTrackThemeHeight}" Grid.Row="1"/>
                            <Rectangle x:Name="HorizontalDecreaseRect" Fill="{TemplateBinding Foreground}" Grid.Row="1"/>
                            <TickBar x:Name="TopTickBar" Grid.ColumnSpan="3" Fill="{ThemeResource SliderTickBarFill}" Height="{ThemeResource SliderOutsideTickBarThemeHeight}" Margin="0,0,0,4" VerticalAlignment="Bottom" Visibility="Collapsed"/>
                            <TickBar x:Name="HorizontalInlineTickBar" Grid.ColumnSpan="3" Fill="{ThemeResource SliderInlineTickBarFill}" Height="{ThemeResource SliderTrackThemeHeight}" Grid.Row="1" Visibility="Collapsed"/>
                            <TickBar x:Name="BottomTickBar" Grid.ColumnSpan="3" Fill="{ThemeResource SliderTickBarFill}" Height="{ThemeResource SliderOutsideTickBarThemeHeight}" Margin="0,4,0,0" Grid.Row="2" VerticalAlignment="Top" Visibility="Collapsed"/>
                            <Thumb x:Name="HorizontalThumb" AutomationProperties.AccessibilityView="Raw" Grid.Column="1" DataContext="{TemplateBinding Value}" FocusVisualMargin="-14,-6,-14,-6" Height="24" Grid.RowSpan="3" Grid.Row="0" Style="{StaticResource SliderThumbStyle}" Width="24"/>
                        </Grid>
                        <Grid x:Name="VerticalTemplate" MinWidth="44" Visibility="Collapsed">
                            <Grid.ColumnDefinitions>
                                <ColumnDefinition Width="18"/>
                                <ColumnDefinition Width="Auto"/>
                                <ColumnDefinition Width="18"/>
                            </Grid.ColumnDefinitions>
                            <Grid.RowDefinitions>
                                <RowDefinition Height="*"/>
                                <RowDefinition Height="Auto"/>
                                <RowDefinition Height="Auto"/>
                            </Grid.RowDefinitions>
                            <Rectangle x:Name="VerticalTrackRect" Grid.Column="1" Fill="{TemplateBinding Background}" Grid.RowSpan="3" Width="{ThemeResource SliderTrackThemeHeight}"/>
                            <Rectangle x:Name="VerticalDecreaseRect" Grid.Column="1" Fill="{TemplateBinding Foreground}" Grid.Row="2"/>
                            <TickBar x:Name="LeftTickBar" Fill="{ThemeResource SliderTickBarFill}" HorizontalAlignment="Right" Margin="0,0,4,0" Grid.RowSpan="3" Visibility="Collapsed" Width="{ThemeResource SliderOutsideTickBarThemeHeight}"/>
                            <TickBar x:Name="VerticalInlineTickBar" Grid.Column="1" Fill="{ThemeResource SliderInlineTickBarFill}" Grid.RowSpan="3" Visibility="Collapsed" Width="{ThemeResource SliderTrackThemeHeight}"/>
                            <TickBar x:Name="RightTickBar" Grid.Column="2" Fill="{ThemeResource SliderTickBarFill}" HorizontalAlignment="Left" Margin="4,0,0,0" Grid.RowSpan="3" Visibility="Collapsed" Width="{ThemeResource SliderOutsideTickBarThemeHeight}"/>
                            <Thumb x:Name="VerticalThumb" AutomationProperties.AccessibilityView="Raw" Grid.ColumnSpan="3" Grid.Column="0" DataContext="{TemplateBinding Value}" FocusVisualMargin="-6,-14,-6,-14" Height="24" Grid.Row="1" Style="{StaticResource SliderThumbStyle}" Width="24"/>
                        </Grid>
                    </Grid>
                </Grid>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

Source code

Example code for this article is available on my GitHub.

Summary

We have taken a look at how the Thumb control within a Slider can be styled. In spite of being a simple trick, it will go long way to making your app more appealing to the users.