Icon as thumb of slider UWP

Question

In my UWP app, I got a slider that I want to have an icon as thumb. After some playing around with the slider template, I'm not smarter than before. Does anybody know to solve my problem?

Answer 1

The key is that the slider template contains another control Thumb which has a special style called SliderThumbStyle which is part of the default Slider template:

<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}"
                        BorderBrush="{TemplateBinding BorderBrush}"
                        BorderThickness="{TemplateBinding BorderThickness}"
                        CornerRadius="4" />                              
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

As you can see, the default implementation uses a plain and simple Border with some corner radius to display the thumb. The advantage of XAML is however that you can put whatever you want inside the ControlTemplate:

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

This will display an image instead of the Border which is what you wanted. If you have a monochromatic icon, you could even use a BitmapIcon:

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

This is useful because the thumb will then automagically use the system accent color as the overlay.

However, there is one more change you will have to do: the default thumb is very small so you may want to modify its size to fit your icon. Search the default slider template for HorizontalThumb and VerticalThumb and set their Height and Width:

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

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

Complete style

<Style x:Key="IconSliderStyle" 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>