Partial border around Textbox

Question

In this screenshot from the Spotify app on my phone, you can see that they did something that looks like a partial border on the bottom left and right sides. I can't find any specific property to emulate that, so can someone explain to me how they did it?

I've tried playing with border radius, but unless I'm doing something wrong, I don't think it's that simple. Do they just have a custom shape underneath it or something?

Answer 1

A better approach is to restyle the TextBox to have two left and right Rectangles on the side and one on the bottom to mimic the half border look.

<Rectangle x:Name="BottomLine" Grid.ColumnSpan="2" Grid.Row="1" Grid.RowSpan="1" VerticalAlignment="Bottom" Height="2" Fill="{TemplateBinding BorderBrush}" />
<Rectangle x:Name="LeftVerticalLine" HorizontalAlignment="Left" Height="4" Margin="0,0,0,2" Grid.Row="1" Stretch="Fill" UseLayoutRounding="True" VerticalAlignment="Bottom" Width="2" RenderTransformOrigin="0.5,1" Fill="{TemplateBinding BorderBrush}">
    <Rectangle.RenderTransform>
        <CompositeTransform />
    </Rectangle.RenderTransform>
</Rectangle>
<Rectangle x:Name="RightVerticalLine" HorizontalAlignment="Right" Height="4" Margin="0,0,0,2" Grid.Row="1" Stretch="Fill" UseLayoutRounding="True" VerticalAlignment="Bottom" Width="2" RenderTransformOrigin="0.5,1" Grid.ColumnSpan="2" Fill="{TemplateBinding BorderBrush}">
    <Rectangle.RenderTransform>
        <CompositeTransform />
    </Rectangle.RenderTransform>
</Rectangle>

Why is it better? Because since they are now components of the TextBox template, you can apply animations to visual states for better user experience.

For example, I want to use ScaleTransform to scale up the left and right Rectangles when the TextBox is in Focused mode to tell users that they are currently interacting with this control.

Here's the full style. :)

<Style x:Key="HalfBorderTextBoxStyle" TargetType="TextBox">
    <Setter Property="FontFamily" Value="{ThemeResource ContentControlThemeFontFamily}" />
    <Setter Property="FontSize" Value="{ThemeResource ControlContentThemeFontSize}" />
    <Setter Property="MinWidth" Value="{ThemeResource TextControlThemeMinWidth}" />
    <Setter Property="MinHeight" Value="{ThemeResource TextControlThemeMinHeight}" />
    <Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Hidden" />
    <Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Hidden" />
    <Setter Property="ScrollViewer.IsDeferredScrollingEnabled" Value="False" />
    <Setter Property="BorderThickness" Value="0,0,0,2" />
    <Setter Property="Padding" Value="8,5" />
    <Setter Property="Foreground">
        <Setter.Value>
            <SolidColorBrush Color="White" />
        </Setter.Value>
    </Setter>
    <Setter Property="Background">
        <Setter.Value>
            <SolidColorBrush Color="Transparent" />
        </Setter.Value>
    </Setter>
    <Setter Property="BorderBrush">
        <Setter.Value>
            <SolidColorBrush Color="#FF8FBE19" />
        </Setter.Value>
    </Setter>
    <Setter Property="SelectionHighlightColor">
        <Setter.Value>
            <SolidColorBrush Color="#FF8FBE19" />
        </Setter.Value>
    </Setter>
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="TextBox">
                <Grid>
                    <Grid.Resources>
                        <Style x:Name="DeleteButtonStyle" TargetType="Button">
                            <Setter Property="Template">
                                <Setter.Value>
                                    <ControlTemplate TargetType="Button">
                                        <Grid x:Name="ButtonLayoutGrid" BorderBrush="{ThemeResource TextBoxButtonBorderThemeBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{ThemeResource TextBoxButtonBackgroundThemeBrush}">
                                            <VisualStateManager.VisualStateGroups>
                                                <VisualStateGroup x:Name="CommonStates">
                                                    <VisualState x:Name="Normal" />
                                                    <VisualState x:Name="PointerOver">
                                                        <Storyboard>
                                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Foreground" Storyboard.TargetName="GlyphElement">
                                                                <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightAccentBrush}" />
                                                            </ObjectAnimationUsingKeyFrames>
                                                        </Storyboard>
                                                    </VisualState>
                                                    <VisualState x:Name="Pressed">
                                                        <Storyboard>
                                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Background" Storyboard.TargetName="ButtonLayoutGrid">
                                                                <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightAccentBrush}" />
                                                            </ObjectAnimationUsingKeyFrames>
                                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Foreground" Storyboard.TargetName="GlyphElement">
                                                                <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightAltChromeWhiteBrush}" />
                                                            </ObjectAnimationUsingKeyFrames>
                                                        </Storyboard>
                                                    </VisualState>
                                                    <VisualState x:Name="Disabled">
                                                        <Storyboard>
                                                            <DoubleAnimation Duration="0" To="0" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="ButtonLayoutGrid" />
                                                        </Storyboard>
                                                    </VisualState>
                                                </VisualStateGroup>
                                            </VisualStateManager.VisualStateGroups>
                                            <TextBlock x:Name="GlyphElement" AutomationProperties.AccessibilityView="Raw" Foreground="{ThemeResource SystemControlForegroundChromeBlackMediumBrush}" FontStyle="Normal" FontSize="12" FontFamily="{ThemeResource SymbolThemeFontFamily}" HorizontalAlignment="Center" Text="&#xE10A;" VerticalAlignment="Center" />
                                        </Grid>
                                    </ControlTemplate>
                                </Setter.Value>
                            </Setter>
                        </Style>
                    </Grid.Resources>
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition Width="*" />
                        <ColumnDefinition Width="Auto" />
                    </Grid.ColumnDefinitions>
                    <Grid.RowDefinitions>
                        <RowDefinition Height="Auto" />
                        <RowDefinition Height="*" />
                    </Grid.RowDefinitions>
                    <VisualStateManager.VisualStateGroups>
                        <VisualStateGroup x:Name="CommonStates">
                            <VisualStateGroup.Transitions>
                                <VisualTransition GeneratedDuration="0:0:0.2" To="Focused">
                                    <VisualTransition.GeneratedEasingFunction>
                                        <ExponentialEase EasingMode="EaseIn" />
                                    </VisualTransition.GeneratedEasingFunction>
                                    <Storyboard>
                                        <DoubleAnimation Duration="0:0:0.2" To="1.4" Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.ScaleY)" Storyboard.TargetName="LeftVerticalLine" d:IsOptimized="True" />
                                        <DoubleAnimation Duration="0:0:0.2" To="1.4" Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.ScaleY)" Storyboard.TargetName="RightVerticalLine" d:IsOptimized="True" />
                                    </Storyboard>
                                </VisualTransition>
                                <VisualTransition From="Focused" GeneratedDuration="0:0:0.2">
                                    <VisualTransition.GeneratedEasingFunction>
                                        <ExponentialEase EasingMode="EaseOut" />
                                    </VisualTransition.GeneratedEasingFunction>
                                    <Storyboard>
                                        <DoubleAnimation Duration="0:0:0.2" To="1" Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.ScaleY)" Storyboard.TargetName="LeftVerticalLine" d:IsOptimized="True" />
                                        <DoubleAnimation Duration="0:0:0.2" To="1" Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.ScaleY)" Storyboard.TargetName="RightVerticalLine" d:IsOptimized="True" />
                                    </Storyboard>
                                </VisualTransition>
                            </VisualStateGroup.Transitions>
                            <VisualState x:Name="Disabled">
                                <VisualState.Setters>
                                    <Setter Target="BorderElement.(UIElement.Opacity)" Value="1" />
                                </VisualState.Setters>
                                <Storyboard>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Foreground" Storyboard.TargetName="HeaderContentPresenter">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlDisabledBaseLowBrush}" />
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="BorderBrush" Storyboard.TargetName="BottomLine">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlDisabledBaseLowBrush}" />
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Foreground" Storyboard.TargetName="ContentElement">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlDisabledChromeDisabledLowBrush}" />
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                            <VisualState x:Name="Normal" />
                            <VisualState x:Name="PointerOver" />
                            <VisualState x:Name="Focused">
                                <VisualState.Setters>
                                    <Setter Target="LeftVerticalLine.(UIElement.Opacity)" Value="1" />
                                    <Setter Target="RightVerticalLine.(UIElement.Opacity)" Value="1" />
                                    <Setter Target="LeftVerticalLine.(UIElement.RenderTransform).(CompositeTransform.ScaleY)" Value="1.4" />
                                    <Setter Target="RightVerticalLine.(UIElement.RenderTransform).(CompositeTransform.ScaleY)" Value="1.4" />
                                </VisualState.Setters>
                                <Storyboard>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Opacity" Storyboard.TargetName="BackgroundElement">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource TextControlBackgroundFocusedOpacity}" />
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                        </VisualStateGroup>
                        <VisualStateGroup x:Name="ButtonStates">
                            <VisualState x:Name="ButtonVisible">
                                <Storyboard>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility" Storyboard.TargetName="DeleteButton">
                                        <DiscreteObjectKeyFrame KeyTime="0">
                                            <DiscreteObjectKeyFrame.Value>
                                                <Visibility>Visible</Visibility>
                                            </DiscreteObjectKeyFrame.Value>
                                        </DiscreteObjectKeyFrame>
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                            <VisualState x:Name="ButtonCollapsed" />
                        </VisualStateGroup>
                    </VisualStateManager.VisualStateGroups>
                    <Border x:Name="BackgroundElement" Background="{TemplateBinding Background}" Grid.ColumnSpan="2" Margin="{TemplateBinding BorderThickness}" Opacity="{ThemeResource TextControlBackgroundRestOpacity}" Grid.Row="1" Grid.RowSpan="1" />
                    <Rectangle x:Name="BottomLine" Grid.ColumnSpan="2" Grid.Row="1" Grid.RowSpan="1" VerticalAlignment="Bottom" Height="2" Fill="{TemplateBinding BorderBrush}" />
                    <Rectangle x:Name="LeftVerticalLine" HorizontalAlignment="Left" Height="4" Margin="0,0,0,2" Grid.Row="1" Stretch="Fill" UseLayoutRounding="True" VerticalAlignment="Bottom" Width="2" RenderTransformOrigin="0.5,1" Fill="{TemplateBinding BorderBrush}">
                        <Rectangle.RenderTransform>
                            <CompositeTransform />
                        </Rectangle.RenderTransform>
                    </Rectangle>
                    <Rectangle x:Name="RightVerticalLine" HorizontalAlignment="Right" Height="4" Margin="0,0,0,2" Grid.Row="1" Stretch="Fill" UseLayoutRounding="True" VerticalAlignment="Bottom" Width="2" RenderTransformOrigin="0.5,1" Grid.ColumnSpan="2" Fill="{TemplateBinding BorderBrush}">
                        <Rectangle.RenderTransform>
                            <CompositeTransform />
                        </Rectangle.RenderTransform>
                    </Rectangle>
                    <ContentPresenter x:Name="HeaderContentPresenter" Grid.ColumnSpan="2" ContentTemplate="{TemplateBinding HeaderTemplate}" Content="{TemplateBinding Header}" Foreground="{ThemeResource SystemControlForegroundBaseHighBrush}" FontWeight="Normal" Margin="0,0,0,8" Grid.Row="0" Visibility="Collapsed" x:DeferLoadStrategy="Lazy" />
                    <ScrollViewer x:Name="ContentElement" AutomationProperties.AccessibilityView="Raw" HorizontalScrollMode="{TemplateBinding ScrollViewer.HorizontalScrollMode}" HorizontalScrollBarVisibility="{TemplateBinding ScrollViewer.HorizontalScrollBarVisibility}" IsTabStop="False" IsHorizontalRailEnabled="{TemplateBinding ScrollViewer.IsHorizontalRailEnabled}" IsVerticalRailEnabled="{TemplateBinding ScrollViewer.IsVerticalRailEnabled}" IsDeferredScrollingEnabled="{TemplateBinding ScrollViewer.IsDeferredScrollingEnabled}" Margin="{TemplateBinding BorderThickness}" Padding="{TemplateBinding Padding}" Grid.Row="1" VerticalScrollBarVisibility="{TemplateBinding ScrollViewer.VerticalScrollBarVisibility}" VerticalScrollMode="{TemplateBinding ScrollViewer.VerticalScrollMode}" ZoomMode="Disabled" />
                    <ContentControl x:Name="PlaceholderTextContentPresenter" Grid.ColumnSpan="2" Content="{TemplateBinding PlaceholderText}" Foreground="{ThemeResource ButtonBackgroundThemeBrush}" IsHitTestVisible="False" IsTabStop="False" Margin="{TemplateBinding BorderThickness}" Padding="{TemplateBinding Padding}" Grid.Row="1" />
                    <Button x:Name="DeleteButton" BorderThickness="{TemplateBinding BorderThickness}" Grid.Column="1" FontSize="{TemplateBinding FontSize}" IsTabStop="False" Margin="{ThemeResource HelperButtonThemePadding}" MinWidth="34" Grid.Row="1" Style="{StaticResource DeleteButtonStyle}" Visibility="Collapsed" VerticalAlignment="Stretch" />
                </Grid>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

Answer 2

You can achieve that using a LinearGradientBrush, and four GradientStop points :

<TextBox Background="WhiteSmoke" BorderThickness="3" Height="50"  Width="200" VerticalAlignment="Center" HorizontalAlignment="Center">
        <TextBox.BorderBrush>
            <LinearGradientBrush EndPoint="1,1" StartPoint="1,0">
                <GradientStop Color="White" Offset="0"/>
                <GradientStop Color="White" Offset="0.75"/>
                <GradientStop Color="Green" Offset="0.75"/>
                <GradientStop Color="Green" Offset="1"/>
            </LinearGradientBrush>
        </TextBox.BorderBrush>
    </TextBox>

and here the result