UWP TextBox with ellipsis for long text when not focused - xaml

Question

I'm looking to create a TextBox in a UWP application that shows an ellipsis at the end of the text if it overruns the bounds of the TextBox.
What I need is similar to this, but for a UWP instead of a WPF app.
I believe I need to create a style that:
When unfocused, the TextBlock within the TextBox has a TextTrimming value of CharacterEllipsis.
When focused, the TextBlock within the TextBox removes the TextTrimming value (or resets to the default).
I am fairly new to UWP development and am unsure how to do this.
I have tried the following approach using ChangePropertyActionbut I am unsure how to target the TextBlock within the TextBox:
<TextBox Name="myTextbox">
<Interactivity:Interaction.Behaviors>
<Core:EventTriggerBehavior EventName="LostFocus">
<Core:ChangePropertyAction TargetObject="?" PropertyName="TextTrimming" Value="CharacterEllipsis"/>
</Core:EventTriggerBehavior>
<Core:EventTriggerBehavior EventName="GotFocus">
<Core:ChangePropertyAction TargetObject="?" PropertyName="TextTrimming" Value=""/>
</Core:EventTriggerBehavior>
</Interactivity:Interaction.Behaviors>
</TextBox>
I might also be going down the wrong path -- As a proof-of-concept, I have tried just customizing the default TextBox style to give the TextBlock control the TextTrimming="CharacterEllipsis" value, but this doesn't work (nor would I really expect it to, being editable text).
Any thoughts or suggestions?

Answer 1

I was able to get a workable solution with the following style derived from the standard TextBox. Any comments on improving this solution are welcome.
<Style x:Key="TextBoxWithEllipsisStyle" TargetType="TextBox">
<Setter Property="MinWidth" Value="{ThemeResource TextControlThemeMinWidth}" />
<Setter Property="MinHeight" Value="{ThemeResource TextControlThemeMinHeight}" />
<Setter Property="Foreground" Value="{ThemeResource TextControlForeground}" />
<Setter Property="Background" Value="{ThemeResource TextControlBackground}" />
<Setter Property="BorderBrush" Value="{ThemeResource TextControlBorderBrush}" />
<Setter Property="SelectionHighlightColor" Value="{ThemeResource TextControlSelectionHighlightColor}" />
<Setter Property="BorderThickness" Value="{ThemeResource TextControlBorderThemeThickness}" />
<Setter Property="FontFamily" Value="{ThemeResource ContentControlThemeFontFamily}" />
<Setter Property="FontSize" Value="{ThemeResource ControlContentThemeFontSize}" />
<Setter Property="ScrollViewer.HorizontalScrollMode" Value="Auto" />
<Setter Property="ScrollViewer.VerticalScrollMode" Value="Auto" />
<Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Hidden" />
<Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Hidden" />
<Setter Property="ScrollViewer.IsDeferredScrollingEnabled" Value="False" />
<Setter Property="Padding" Value="{ThemeResource TextControlThemePadding}" />
<Setter Property="UseSystemFocusVisuals" Value="{ThemeResource IsApplicationFocusVisualKindReveal}" />
<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 TextControlButtonBorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}"
Background="{ThemeResource TextControlButtonBackground}">
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="Normal" />
<VisualState x:Name="PointerOver">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="ButtonLayoutGrid" Storyboard.TargetProperty="Background">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource TextControlButtonBackgroundPointerOver}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="ButtonLayoutGrid" Storyboard.TargetProperty="BorderBrush">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource TextControlButtonBorderBrushPointerOver}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="GlyphElement" Storyboard.TargetProperty="Foreground">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource TextControlButtonForegroundPointerOver}" />
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Pressed">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="ButtonLayoutGrid" Storyboard.TargetProperty="Background">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource TextControlButtonBackgroundPressed}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="ButtonLayoutGrid" Storyboard.TargetProperty="BorderBrush">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource TextControlButtonBorderBrushPressed}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="GlyphElement" Storyboard.TargetProperty="Foreground">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource TextControlButtonForegroundPressed}" />
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Disabled">
<Storyboard>
<DoubleAnimation Storyboard.TargetName="ButtonLayoutGrid"
Storyboard.TargetProperty="Opacity"
To="0"
Duration="0" />
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<TextBlock x:Name="GlyphElement"
Foreground="{ThemeResource TextControlButtonForeground}"
VerticalAlignment="Center"
HorizontalAlignment="Center"
FontStyle="Normal"
FontSize="12"
Text=""
FontFamily="{ThemeResource SymbolThemeFontFamily}"
AutomationProperties.AccessibilityView="Raw" />
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Grid.Resources>
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="Disabled">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="HeaderContentPresenter" Storyboard.TargetProperty="Foreground">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource TextControlHeaderForegroundDisabled}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="BorderElement" Storyboard.TargetProperty="Background">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource TextControlBackgroundDisabled}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="BorderElement" Storyboard.TargetProperty="BorderBrush">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource TextControlBorderBrushDisabled}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentElement" Storyboard.TargetProperty="Foreground">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource TextControlForegroundDisabled}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="PlaceholderTextContentPresenter" Storyboard.TargetProperty="Foreground">
<DiscreteObjectKeyFrame KeyTime="0" Value="{Binding PlaceholderForeground, RelativeSource={RelativeSource TemplatedParent}, TargetNullValue={ThemeResource TextControlPlaceholderForegroundDisabled}}" />
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Normal">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentElement" Storyboard.TargetProperty="Visibility">
<DiscreteObjectKeyFrame KeyTime="0" Value="Collapsed" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="EllipsisContentElement" Storyboard.TargetProperty="Visibility">
<DiscreteObjectKeyFrame KeyTime="0" Value="Visible" />
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="PointerOver">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="BorderElement" Storyboard.TargetProperty="BorderBrush">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource TextControlBorderBrushPointerOver}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="BorderElement" Storyboard.TargetProperty="Background">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource TextControlBackgroundPointerOver}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="PlaceholderTextContentPresenter" Storyboard.TargetProperty="Foreground">
<DiscreteObjectKeyFrame KeyTime="0" Value="{Binding PlaceholderForeground, RelativeSource={RelativeSource TemplatedParent}, TargetNullValue={ThemeResource TextControlPlaceholderForegroundPointerOver}}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentElement" Storyboard.TargetProperty="Foreground">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource TextControlForegroundPointerOver}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentElement" Storyboard.TargetProperty="Visibility">
<DiscreteObjectKeyFrame KeyTime="0" Value="Collapsed" />
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Focused">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="PlaceholderTextContentPresenter" Storyboard.TargetProperty="Foreground">
<DiscreteObjectKeyFrame KeyTime="0" Value="{Binding PlaceholderForeground, RelativeSource={RelativeSource TemplatedParent}, TargetNullValue={ThemeResource TextControlPlaceholderForegroundFocused}}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="BorderElement" Storyboard.TargetProperty="Background">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource TextControlBackgroundFocused}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="BorderElement" Storyboard.TargetProperty="BorderBrush">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource TextControlBorderBrushFocused}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentElement" Storyboard.TargetProperty="Foreground">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource TextControlForegroundFocused}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentElement" Storyboard.TargetProperty="RequestedTheme">
<DiscreteObjectKeyFrame KeyTime="0" Value="Light" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentElement" Storyboard.TargetProperty="Visibility">
<DiscreteObjectKeyFrame KeyTime="0" Value="Visible" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="EllipsisContentElement" Storyboard.TargetProperty="Visibility">
<DiscreteObjectKeyFrame KeyTime="0" Value="Collapsed" />
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="ButtonStates">
<VisualState x:Name="ButtonVisible">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="DeleteButton" Storyboard.TargetProperty="Visibility">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Visible</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="ButtonCollapsed" />
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="Auto" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<Border x:Name="BorderElement"
Grid.Row="1"
Background="{TemplateBinding Background}"
BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}"
Grid.ColumnSpan="2"
Grid.RowSpan="1"
Control.IsTemplateFocusTarget="True" />
<ContentPresenter x:Name="HeaderContentPresenter"
x:DeferLoadStrategy="Lazy"
Visibility="Collapsed"
Grid.Row="0"
Foreground="{ThemeResource TextControlHeaderForeground}"
Margin="0,0,0,8"
Grid.ColumnSpan="2"
Content="{TemplateBinding Header}"
ContentTemplate="{TemplateBinding HeaderTemplate}"
TextWrapping="{TemplateBinding TextWrapping}"
FontWeight="Normal" />
<ScrollViewer x:Name="ContentElement"
Grid.Row="1"
HorizontalScrollMode="{TemplateBinding ScrollViewer.HorizontalScrollMode}"
HorizontalScrollBarVisibility="{TemplateBinding ScrollViewer.HorizontalScrollBarVisibility}"
VerticalScrollMode="{TemplateBinding ScrollViewer.VerticalScrollMode}"
VerticalScrollBarVisibility="{TemplateBinding ScrollViewer.VerticalScrollBarVisibility}"
IsHorizontalRailEnabled="{TemplateBinding ScrollViewer.IsHorizontalRailEnabled}"
IsVerticalRailEnabled="{TemplateBinding ScrollViewer.IsVerticalRailEnabled}"
IsDeferredScrollingEnabled="{TemplateBinding ScrollViewer.IsDeferredScrollingEnabled}"
Margin="{TemplateBinding BorderThickness}"
Padding="{TemplateBinding Padding}"
IsTabStop="False"
AutomationProperties.AccessibilityView="Raw"
ZoomMode="Disabled" />
<TextBlock x:Name="PlaceholderTextContentPresenter"
Grid.Row="1"
Foreground="{Binding PlaceholderForeground, RelativeSource={RelativeSource TemplatedParent}, TargetNullValue={ThemeResource TextControlPlaceholderForeground}}"
Margin="{TemplateBinding BorderThickness}"
Padding="{TemplateBinding Padding}"
Grid.ColumnSpan="2"
Text="{TemplateBinding PlaceholderText}"
TextWrapping="{TemplateBinding TextWrapping}"
TextAlignment="{TemplateBinding TextAlignment}"
IsHitTestVisible="False" />
<Button x:Name="DeleteButton"
Grid.Row="1"
Style="{StaticResource DeleteButtonStyle}"
BorderThickness="{TemplateBinding BorderThickness}"
Margin="{ThemeResource HelperButtonThemePadding}"
IsTabStop="False"
Grid.Column="1"
Visibility="Collapsed"
AutomationProperties.AccessibilityView="Raw"
FontSize="{TemplateBinding FontSize}"
MinWidth="34"
VerticalAlignment="Stretch" />
<TextBlock x:Name="EllipsisContentElement"
Grid.Row="1"
Foreground="{TemplateBinding Foreground}"
Margin="{TemplateBinding BorderThickness}"
Padding="{TemplateBinding Padding}"
Grid.ColumnSpan="2"
Text="{TemplateBinding Text}"
TextWrapping="{TemplateBinding TextWrapping}"
TextAlignment="{TemplateBinding TextAlignment}"
TextTrimming="CharacterEllipsis"/>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>