Apply stroke to a textblock in WPF

Question

How do you apply stroke (outline around text) to a textblock in xaml in WPF?

user_5380 · Answer

Below is my more idiomatically WPF, full-featured take on this. It supports pretty much everything you'd expect, including:

all font related properties including stretch and style
text alignment (left, right, center, justify)
text wrapping
text trimming
text decorations (underline, strike through etcetera)

Here's a simple example of what can be achieved with it:


    Neque porro quisquam est qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit

Which results in:

enter image description here

Here's the code for the control:

using System;
using System.ComponentModel;
using System.Globalization;
using System.Windows;
using System.Windows.Documents;
using System.Windows.Markup;
using System.Windows.Media;

[ContentProperty("Text")]
public class OutlinedTextBlock : FrameworkElement
{
    public static readonly DependencyProperty FillProperty = DependencyProperty.Register(
        "Fill",
        typeof(Brush),
        typeof(OutlinedTextBlock),
        new FrameworkPropertyMetadata(Brushes.Black, FrameworkPropertyMetadataOptions.AffectsRender));

    public static readonly DependencyProperty StrokeProperty = DependencyProperty.Register(
        "Stroke",
        typeof(Brush),
        typeof(OutlinedTextBlock),
        new FrameworkPropertyMetadata(Brushes.Black, FrameworkPropertyMetadataOptions.AffectsRender));

    public static readonly DependencyProperty StrokeThicknessProperty = DependencyProperty.Register(
        "StrokeThickness",
        typeof(double),
        typeof(OutlinedTextBlock),
        new FrameworkPropertyMetadata(1d, FrameworkPropertyMetadataOptions.AffectsRender));

    public static readonly DependencyProperty FontFamilyProperty = TextElement.FontFamilyProperty.AddOwner(
        typeof(OutlinedTextBlock),
        new FrameworkPropertyMetadata(OnFormattedTextUpdated));

    public static readonly DependencyProperty FontSizeProperty = TextElement.FontSizeProperty.AddOwner(
        typeof(OutlinedTextBlock),
        new FrameworkPropertyMetadata(OnFormattedTextUpdated));

    public static readonly DependencyProperty FontStretchProperty = TextElement.FontStretchProperty.AddOwner(
        typeof(OutlinedTextBlock),
        new FrameworkPropertyMetadata(OnFormattedTextUpdated));

    public static readonly DependencyProperty FontStyleProperty = TextElement.FontStyleProperty.AddOwner(
        typeof(OutlinedTextBlock),
        new FrameworkPropertyMetadata(OnFormattedTextUpdated));

    public static readonly DependencyProperty FontWeightProperty = TextElement.FontWeightProperty.AddOwner(
        typeof(OutlinedTextBlock),
        new FrameworkPropertyMetadata(OnFormattedTextUpdated));

    public static readonly DependencyProperty TextProperty = DependencyProperty.Register(
        "Text",
        typeof(string),
        typeof(OutlinedTextBlock),
        new FrameworkPropertyMetadata(OnFormattedTextInvalidated));

    public static readonly DependencyProperty TextAlignmentProperty = DependencyProperty.Register(
        "TextAlignment",
        typeof(TextAlignment),
        typeof(OutlinedTextBlock),
        new FrameworkPropertyMetadata(OnFormattedTextUpdated));

    public static readonly DependencyProperty TextDecorationsProperty = DependencyProperty.Register(
        "TextDecorations",
        typeof(TextDecorationCollection),
        typeof(OutlinedTextBlock),
        new FrameworkPropertyMetadata(OnFormattedTextUpdated));

    public static readonly DependencyProperty TextTrimmingProperty = DependencyProperty.Register(
        "TextTrimming",
        typeof(TextTrimming),
        typeof(OutlinedTextBlock),
        new FrameworkPropertyMetadata(OnFormattedTextUpdated));

    public static readonly DependencyProperty TextWrappingProperty = DependencyProperty.Register(
        "TextWrapping",
        typeof(TextWrapping),
        typeof(OutlinedTextBlock),
        new FrameworkPropertyMetadata(TextWrapping.NoWrap, OnFormattedTextUpdated));

    private FormattedText formattedText;
    private Geometry textGeometry;

    public OutlinedTextBlock()
    {
        this.TextDecorations = new TextDecorationCollection();
    }

    public Brush Fill
    {
        get { return (Brush)GetValue(FillProperty); }
        set { SetValue(FillProperty, value); }
    }

    public FontFamily FontFamily
    {
        get { return (FontFamily)GetValue(FontFamilyProperty); }
        set { SetValue(FontFamilyProperty, value); }
    }

    [TypeConverter(typeof(FontSizeConverter))]
    public double FontSize
    {
        get { return (double)GetValue(FontSizeProperty); }
        set { SetValue(FontSizeProperty, value); }
    }

    public FontStretch FontStretch
    {
        get { return (FontStretch)GetValue(FontStretchProperty); }
        set { SetValue(FontStretchProperty, value); }
    }

    public FontStyle FontStyle
    {
        get { return (FontStyle)GetValue(FontStyleProperty); }
        set { SetValue(FontStyleProperty, value); }
    }

    public FontWeight FontWeight
    {
        get { return (FontWeight)GetValue(FontWeightProperty); }
        set { SetValue(FontWeightProperty, value); }
    }

    public Brush Stroke
    {
        get { return (Brush)GetValue(StrokeProperty); }
        set { SetValue(StrokeProperty, value); }
    }

    public double StrokeThickness
    {
        get { return (double)GetValue(StrokeThicknessProperty); }
        set { SetValue(StrokeThicknessProperty, value); }
    }

    public string Text
    {
        get { return (string)GetValue(TextProperty); }
        set { SetValue(TextProperty, value); }
    }

    public TextAlignment TextAlignment
    {
        get { return (TextAlignment)GetValue(TextAlignmentProperty); }
        set { SetValue(TextAlignmentProperty, value); }
    }

    public TextDecorationCollection TextDecorations
    {
        get { return (TextDecorationCollection)this.GetValue(TextDecorationsProperty); }
        set { this.SetValue(TextDecorationsProperty, value); }
    }

    public TextTrimming TextTrimming
    {
        get { return (TextTrimming)GetValue(TextTrimmingProperty); }
        set { SetValue(TextTrimmingProperty, value); }
    }

    public TextWrapping TextWrapping
    {
        get { return (TextWrapping)GetValue(TextWrappingProperty); }
        set { SetValue(TextWrappingProperty, value); }
    }

    protected override void OnRender(DrawingContext drawingContext)
    {
        this.EnsureGeometry();

        drawingContext.DrawGeometry(this.Fill, new Pen(this.Stroke, this.StrokeThickness), this.textGeometry);
    }

    protected override Size MeasureOverride(Size availableSize)
    {
        this.EnsureFormattedText();

        // constrain the formatted text according to the available size
        // the Math.Min call is important - without this constraint (which seems arbitrary, but is the maximum allowable text width), things blow up when availableSize is infinite in both directions
        // the Math.Max call is to ensure we don't hit zero, which will cause MaxTextHeight to throw
        this.formattedText.MaxTextWidth = Math.Min(3579139, availableSize.Width);
        this.formattedText.MaxTextHeight = Math.Max(0.0001d, availableSize.Height);

        // return the desired size
        return new Size(this.formattedText.Width, this.formattedText.Height);
    }

    protected override Size ArrangeOverride(Size finalSize)
    {
        this.EnsureFormattedText();

        // update the formatted text with the final size
        this.formattedText.MaxTextWidth = finalSize.Width;
        this.formattedText.MaxTextHeight = finalSize.Height;

        // need to re-generate the geometry now that the dimensions have changed
        this.textGeometry = null;

        return finalSize;
    }

    private static void OnFormattedTextInvalidated(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs e)
    {
        var outlinedTextBlock = (OutlinedTextBlock)dependencyObject;
        outlinedTextBlock.formattedText = null;
        outlinedTextBlock.textGeometry = null;

        outlinedTextBlock.InvalidateMeasure();
        outlinedTextBlock.InvalidateVisual();
    }

    private static void OnFormattedTextUpdated(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs e)
    {
        var outlinedTextBlock = (OutlinedTextBlock)dependencyObject;
        outlinedTextBlock.UpdateFormattedText();
        outlinedTextBlock.textGeometry = null;

        outlinedTextBlock.InvalidateMeasure();
        outlinedTextBlock.InvalidateVisual();
    }

    private void EnsureFormattedText()
    {
        if (this.formattedText != null || this.Text == null)
        {
            return;
        }

        this.formattedText = new FormattedText(
            this.Text,
            CultureInfo.CurrentUICulture,
            this.FlowDirection,
            new Typeface(this.FontFamily, this.FontStyle, this.FontWeight, FontStretches.Normal),
            this.FontSize,
            Brushes.Black);

        this.UpdateFormattedText();
    }

    private void UpdateFormattedText()
    {
        if (this.formattedText == null)
        {
            return;
        }

        this.formattedText.MaxLineCount = this.TextWrapping == TextWrapping.NoWrap ? 1 : int.MaxValue;
        this.formattedText.TextAlignment = this.TextAlignment;
        this.formattedText.Trimming = this.TextTrimming;

        this.formattedText.SetFontSize(this.FontSize);
        this.formattedText.SetFontStyle(this.FontStyle);
        this.formattedText.SetFontWeight(this.FontWeight);
        this.formattedText.SetFontFamily(this.FontFamily);
        this.formattedText.SetFontStretch(this.FontStretch);
        this.formattedText.SetTextDecorations(this.TextDecorations);
    }

    private void EnsureGeometry()
    {
        if (this.textGeometry != null)
        {
            return;
        }

        this.EnsureFormattedText();
        this.textGeometry = this.formattedText.BuildGeometry(new Point(0, 0));
    }
}

Kris_Erickson_3798 · Answer

Found It. Not so easy to do apparently, there is no built in Stroke text in WPF (kind of a big missing feature if you ask me). First create the custom class:

using System;
using System.Windows.Media;
using System.Globalization;
using System.Windows;
using System.Windows.Markup;

namespace CustomXaml
{

public class OutlinedText : FrameworkElement, IAddChild
{
    #region Private Fields

    private Geometry _textGeometry;

    #endregion

    #region Private Methods

    /// 
    /// Invoked when a dependency property has changed. Generate a new FormattedText object to display.
    /// 
    /// OutlineText object whose property was updated.
    /// Event arguments for the dependency property.
    private static void OnOutlineTextInvalidated(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        ((OutlinedText)d).CreateText();
    }

    #endregion


    #region FrameworkElement Overrides

    /// 
    /// OnRender override draws the geometry of the text and optional highlight.
    /// 
    /// Drawing context of the OutlineText control.
    protected override void OnRender(DrawingContext drawingContext)
    {
        CreateText();
        // Draw the outline based on the properties that are set.
        drawingContext.DrawGeometry(Fill, new Pen(Stroke, StrokeThickness), _textGeometry);

    }

    /// 
    /// Create the outline geometry based on the formatted text.
    /// 
    public void CreateText()
    {
        FontStyle fontStyle = FontStyles.Normal;
        FontWeight fontWeight = FontWeights.Medium;

        if (Bold == true) fontWeight = FontWeights.Bold;
        if (Italic == true) fontStyle = FontStyles.Italic;

        // Create the formatted text based on the properties set.
        FormattedText formattedText = new FormattedText(
            Text,
            CultureInfo.GetCultureInfo("en-us"),                
            FlowDirection.LeftToRight,
            new Typeface(Font, fontStyle, fontWeight, FontStretches.Normal),                
            FontSize,
            Brushes.Black // This brush does not matter since we use the geometry of the text. 
            );

        // Build the geometry object that represents the text.
        _textGeometry = formattedText.BuildGeometry(new Point(0, 0));




        //set the size of the custome control based on the size of the text
        this.MinWidth = formattedText.Width;
        this.MinHeight = formattedText.Height;

    }

    #endregion

    #region DependencyProperties

    /// 
    /// Specifies whether the font should display Bold font weight.
    /// 
    public bool Bold
    {
        get
        {
            return (bool)GetValue(BoldProperty);
        }

        set
        {
            SetValue(BoldProperty, value);
        }
    }

    /// 
    /// Identifies the Bold dependency property.
    /// 
    public static readonly DependencyProperty BoldProperty = DependencyProperty.Register(
        "Bold",
        typeof(bool),
        typeof(OutlinedText),
        new FrameworkPropertyMetadata(
            false,
            FrameworkPropertyMetadataOptions.AffectsRender,
            new PropertyChangedCallback(OnOutlineTextInvalidated),
            null
            )
        );

    /// 
    /// Specifies the brush to use for the fill of the formatted text.
    /// 
    public Brush Fill
    {
        get
        {
            return (Brush)GetValue(FillProperty);
        }

        set
        {
            SetValue(FillProperty, value);
        }
    }

    /// 
    /// Identifies the Fill dependency property.
    /// 
    public static readonly DependencyProperty FillProperty = DependencyProperty.Register(
        "Fill",
        typeof(Brush),
        typeof(OutlinedText),
        new FrameworkPropertyMetadata(
            new SolidColorBrush(Colors.LightSteelBlue),
            FrameworkPropertyMetadataOptions.AffectsRender,
            new PropertyChangedCallback(OnOutlineTextInvalidated),
            null
            )
        );

    /// 
    /// The font to use for the displayed formatted text.
    /// 
    public FontFamily Font
    {
        get
        {
            return (FontFamily)GetValue(FontProperty);
        }

        set
        {
            SetValue(FontProperty, value);
        }
    }

    /// 
    /// Identifies the Font dependency property.
    /// 
    public static readonly DependencyProperty FontProperty = DependencyProperty.Register(
        "Font",
        typeof(FontFamily),
        typeof(OutlinedText),
        new FrameworkPropertyMetadata(
            new FontFamily("Arial"),
            FrameworkPropertyMetadataOptions.AffectsRender,
            new PropertyChangedCallback(OnOutlineTextInvalidated),
            null
            )
        );

    /// 
    /// The current font size.
    /// 
    public double FontSize
    {
        get
        {
            return (double)GetValue(FontSizeProperty);
        }

        set
        {
            SetValue(FontSizeProperty, value);
        }
    }

    /// 
    /// Identifies the FontSize dependency property.
    /// 
    public static readonly DependencyProperty FontSizeProperty = DependencyProperty.Register(
        "FontSize",
        typeof(double),
        typeof(OutlinedText),
        new FrameworkPropertyMetadata(
             (double)48.0,
             FrameworkPropertyMetadataOptions.AffectsRender,
             new PropertyChangedCallback(OnOutlineTextInvalidated),
             null
             )
        );


    /// 
    /// Specifies whether the font should display Italic font style.
    /// 
    public bool Italic
    {
        get
        {
            return (bool)GetValue(ItalicProperty);
        }

        set
        {
            SetValue(ItalicProperty, value);
        }
    }

    /// 
    /// Identifies the Italic dependency property.
    /// 
    public static readonly DependencyProperty ItalicProperty = DependencyProperty.Register(
        "Italic",
        typeof(bool),
        typeof(OutlinedText),
        new FrameworkPropertyMetadata(
             false,
             FrameworkPropertyMetadataOptions.AffectsRender,
             new PropertyChangedCallback(OnOutlineTextInvalidated),
             null
             )
        );

    /// 
    /// Specifies the brush to use for the stroke and optional hightlight of the formatted text.
    /// 
    public Brush Stroke
    {
        get
        {
            return (Brush)GetValue(StrokeProperty);
        }

        set
        {
            SetValue(StrokeProperty, value);
        }
    }

    /// 
    /// Identifies the Stroke dependency property.
    /// 
    public static readonly DependencyProperty StrokeProperty = DependencyProperty.Register(
        "Stroke",
        typeof(Brush),
        typeof(OutlinedText),
        new FrameworkPropertyMetadata(
             new SolidColorBrush(Colors.Teal),
             FrameworkPropertyMetadataOptions.AffectsRender,
             new PropertyChangedCallback(OnOutlineTextInvalidated),
             null
             )
        );

    /// 
    ///     The stroke thickness of the font.
    /// 
    public ushort StrokeThickness
    {
        get
        {
            return (ushort)GetValue(StrokeThicknessProperty);
        }

        set
        {
            SetValue(StrokeThicknessProperty, value);
        }
    }

    /// 
    /// Identifies the StrokeThickness dependency property.
    /// 
    public static readonly DependencyProperty StrokeThicknessProperty = DependencyProperty.Register(
        "StrokeThickness",
        typeof(ushort),
        typeof(OutlinedText),
        new FrameworkPropertyMetadata(
             (ushort)0,
             FrameworkPropertyMetadataOptions.AffectsRender,
             new PropertyChangedCallback(OnOutlineTextInvalidated),
             null
             )
        );

    /// 
    /// Specifies the text string to display.
    /// 
    public string Text
    {
        get
        {
            return (string)GetValue(TextProperty);
        }

        set
        {
            SetValue(TextProperty, value);
        }
    }

    /// 
    /// Identifies the Text dependency property.
    /// 
    public static readonly DependencyProperty TextProperty = DependencyProperty.Register(
        "Text",
        typeof(string),
        typeof(OutlinedText),
        new FrameworkPropertyMetadata(
             "",
             FrameworkPropertyMetadataOptions.AffectsRender,
             new PropertyChangedCallback(OnOutlineTextInvalidated),
             null
             )
        );

    public void AddChild(Object value)
    {

    }

    public void AddText(string value)
    {
        Text = value;
    }

    #endregion
}
}

The you can reference it in your xaml.

SmartyP_18005 · Answer

you should wrap the TextBlock with a Border.. something like this:

    
        My fancy TextBlock

in the off chance you are asking how to put a stroke around the actual letters (and not the whole TextBlock) you may want to look at using a BitmapEffect of Glow and setting the parameters on the Glow to be the stroke color you want, etc. Otherwise you may have to create something custom.

Ifeanyi_Echeruo_47702 · Answer

"How to: Create Outlined Text" on MSDN has all the information you need.

user_10031539 · Answer

as already mentioned, convert text to path

FormattedText t = new FormattedText
(
    "abcxyz",
    CultureInfo.GetCultureInfo("en-us"),
    FlowDirection.LeftToRight,
    new Typeface(
    new FontFamily("Arial"),
    new FontStyle(),
    new FontWeight(),
    new FontStretch()),
    20,
    Brushes.Transparent
);

Geometry g = t.BuildGeometry(new System.Windows.Point(0, 0));

Path p = new Path();
p.Fill = Brushes.White;
p.Stroke = Brushes.Black;
p.StrokeThickness = 1;
p.Data = g;

user_5617177 · Answer

Another option is to use a regular Textblock, but apply a custom effect to it.

Combining this Shader tutorial and the Prewitt Edge Detection Filter I managed to get a decent outline effect around text. While it has the advantage of rendering using the GPU, and applying to ANY UIElement, I'd say that @Kent Boogaart's answer looks a little better, and the EdgeResponse is finicky - I had to play with it a lot to get a nice outline.

The end result in XAML:

In order to create the custom effect, I first created the EdgeDetectionColorEffect.fx (hdld) file - this is the code the GPU uses to filter the image. I compiled it in Visual Studio Command Prompt with the command:

fxc /T ps_2_0 /E main /Focc.ps EdgeDetectionColorEffect.fx

sampler2D Input : register(s0);
float ActualWidth : register(c0);
float ActualHeight : register(c1);
float4 OutlineColor : register(c2);
float EdgeDetectionResponse : register(c3);

float4 GetNeighborPixel(float2 pixelPoint, float xOffset, float yOffset)
{
    float2 NeighborPoint = {pixelPoint.x + xOffset, pixelPoint.y + yOffset};
    return tex2D(Input, NeighborPoint);
}

// pixel locations:
// 00 01 02
// 10 11 12
// 20 21 22
float main(float2 pixelPoint : TEXCOORD) : COLOR
{

     float wo = 1 / ActualWidth; //WidthOffset
     float ho = 1 / ActualHeight; //HeightOffset

    float4 c00 = GetNeighborPixel(pixelPoint, -wo, -ho); // color of the pixel up and to the left of me.
    float4 c01 = GetNeighborPixel(pixelPoint,  00, -ho);        
    float4 c02 = GetNeighborPixel(pixelPoint,  wo, -ho);
    float4 c10 = GetNeighborPixel(pixelPoint, -wo,   0);
    float4 c11 = tex2D(Input, pixelPoint); // this is the current pixel
    float4 c12 = GetNeighborPixel(pixelPoint,  wo,   0);
    float4 c20 = GetNeighborPixel(pixelPoint, -wo,  ho);
    float4 c21 = GetNeighborPixel(pixelPoint,   0,  ho);
    float4 c22 = GetNeighborPixel(pixelPoint,  wo,  ho);

    float t00 = c00.r + c00.g + c00.b; //total of color channels
    float t01 = c01.r + c01.g + c01.b;
    float t02 = c02.r + c02.g + c02.b;
    float t10 = c10.r + c10.g + c10.b;
    float t11 = c11.r + c11.g + c11.b;
    float t12 = c12.r + c12.g + c12.b;
    float t20 = c20.r + c20.g + c20.b;
    float t21 = c21.r + c21.g + c21.b;
    float t22 = c22.r + c22.g + c22.b;

    //Prewitt - convolve the 9 pixels with:
    //       01 01 01        01 00 -1
    // Gy =  00 00 00   Gx = 01 00 -1
    //       -1 -1 -1        01 00 -1

    float gy = 0.0;  float gx = 0.0;
    gy += t00;       gx += t00;
    gy += t01;       gx += t10;
    gy += t02;       gx += t20;
    gy -= t20;       gx -= t02;
    gy -= t21;       gx -= t12;
    gy -= t22;       gx -= t22;

    if((gy*gy + gx*gx) > EdgeDetectionResponse)
    {
        return OutlineColor;
    }

    return c11;
}

Here's the wpf effect class:

public class EdgeDetectionEffect : ShaderEffect
{
    private static PixelShader _shader = new PixelShader { UriSource = new Uri("path to your compiled shader probably called cc.ps", UriKind.Absolute) };

public EdgeDetectionEffect()
{
    PixelShader = _shader;
    UpdateShaderValue(InputProperty);
    UpdateShaderValue(ActualHeightProperty);
    UpdateShaderValue(ActualWidthProperty);
    UpdateShaderValue(OutlineColorProperty);
    UpdateShaderValue(EdgeResponseProperty);
}

public Brush Input
{
     get => (Brush)GetValue(InputProperty);
     set => SetValue(InputProperty, value);
}
public static readonly DependencyProperty InputProperty = 
    ShaderEffect.RegisterPixelShaderSamplerProperty(nameof(Input), 
    typeof(EdgeDetectionEffect), 0);

public double ActualWidth
{
     get => (double)GetValue(ActualWidthProperty);
     set => SetValue(ActualWidthProperty, value);
}
public static readonly DependencyProperty ActualWidthProperty =
    DependencyProperty.Register(nameof(ActualWidth), typeof(double), typeof(EdgeDetectionEffect),
    new UIPropertyMetadata(1.0, PixelShaderConstantCallback(0)));

public double ActualHeight
{
     get => (double)GetValue(ActualHeightProperty);
     set => SetValue(ActualHeightProperty, value);
}
public static readonly DependencyProperty ActualHeightProperty =
    DependencyProperty.Register(nameof(ActualHeight), typeof(double), typeof(EdgeDetectionEffect),
    new UIPropertyMetadata(1.0, PixelShaderConstantCallback(1)));

public Color OutlineColor
{
     get => (Color)GetValue(OutlineColorProperty);
     set => SetValue(OutlineColorProperty, value);
}
public static readonly DependencyProperty OutlineColorProperty=
    DependencyProperty.Register(nameof(OutlineColor), typeof(Color), typeof(EdgeDetectionEffect),
    new UIPropertyMetadata(Colors.Black, PixelShaderConstantCallback(2)));

public double EdgeResponse
{
     get => (double)GetValue(EdgeResponseProperty);
     set => SetValue(EdgeResponseProperty, value);
}
public static readonly DependencyProperty EdgeResponseProperty =
    DependencyProperty.Register(nameof(EdgeResponse), typeof(double), typeof(EdgeDetectionEffect),
    new UIPropertyMetadata(4.0, PixelShaderConstantCallback(3)));
}

Tim_Erickson_8787 · Answer

In Blend you could convert the TextBlock to a Path, and then use the normal Stroke properties. But I'm assuming you wanted something that you could make dynamic...

Otherwise I would think it would have to be some sort of bitmap effect or special brush.

kaiznet_3714 · Answer

has no decorative attributes itself. I would put it on a

user_136059 · Answer

Could just use a Label instead. It has more properties that you can play with. Example:

user_13668671 · Answer

Since I have another answer, I'll post it for the record. I think it is a less elegant one, without using Geometry, Path and FormattedText, though simpler, and (if you know I'd like to know) might be faster to render ?? It basically had the same text 8 times, but shifted on all cardinal direction.

here is the code of my UserControl :

/// 
/// User Control to display a Text with an outline
/// 
public partial class OutlinedText : UserControl, INotifyPropertyChanged
{

    #region DependencyProperties

    /// 
    /// The Text to render
    /// 
    public string Text
    {
        get { return (string)GetValue(TextProperty); }
        set { SetValue(TextProperty, value); }
    }

    // Using a DependencyProperty as the backing store for Text.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty TextProperty =
        DependencyProperty.Register("Text", typeof(string), typeof(OutlinedText), new PropertyMetadata(""));

    /// 
    /// The size (thickness) of the Stroke
    /// 
    public int StrokeSize
    {
        get { return (int)GetValue(StrokeSizeProperty); }
        set { SetValue(StrokeSizeProperty, value); }
    }

    // Using a DependencyProperty as the backing store for StrokeSize.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty StrokeSizeProperty =
        DependencyProperty.Register("StrokeSize", typeof(int), typeof(OutlinedText), new PropertyMetadata(1));

    /// 
    /// The Color of the Stroke
    /// 
    public Brush StrokeColor
    {
        get { return (Brush)GetValue(StrokeColorProperty); }
        set { SetValue(StrokeColorProperty, value); }
    }

    // Using a DependencyProperty as the backing store for StrokeColor.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty StrokeColorProperty =
        DependencyProperty.Register("StrokeColor", typeof(Brush), typeof(OutlinedText), new PropertyMetadata(Brushes.Black));

    #endregion

    #region ctor
    public OutlinedText()
    {
        InitializeComponent();
        this.DataContext = this;
    } 
    #endregion

    public event PropertyChangedEventHandler PropertyChanged;
    protected virtual void OnPropertyChanged(string propertyName)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

and on XAML side :

The used converter here is a simple *(-1) on an integer, to avoid using another property.

Usage :

Apply stroke to a textblock in WPF

18 Answers