Я изменил @Javier G. ответ
Положение обводки может быть: по центру, снаружи или внутри, по умолчанию
снаружи.
Заполнение может быть прозрачным.
Центр:
Внешний вид:
Внутри:
Код:
using System;
using System.ComponentModel;
using System.Globalization;
using System.Windows;
using System.Windows.Documents;
using System.Windows.Markup;
using System.Windows.Media;
namespace WpfApp2
{
public enum StrokePosition
{
Center,
Outside,
Inside
}
[ContentProperty("Text")]
public class OutlinedTextBlock : FrameworkElement
{
private void UpdatePen()
{
_Pen = new Pen(Stroke, StrokeThickness)
{
DashCap = PenLineCap.Round,
EndLineCap = PenLineCap.Round,
LineJoin = PenLineJoin.Round,
StartLineCap = PenLineCap.Round
};
if (StrokePosition == StrokePosition.Outside || StrokePosition == StrokePosition.Inside)
{
_Pen.Thickness = StrokeThickness * 2;
}
InvalidateVisual();
}
public StrokePosition StrokePosition
{
get { return (StrokePosition)GetValue(StrokePositionProperty); }
set { SetValue(StrokePositionProperty, value); }
}
public static readonly DependencyProperty StrokePositionProperty =
DependencyProperty.Register("StrokePosition",
typeof(StrokePosition),
typeof(OutlinedTextBlock),
new FrameworkPropertyMetadata(StrokePosition.Outside, FrameworkPropertyMetadataOptions.AffectsRender));
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;
private Pen _Pen;
private PathGeometry _clipGeometry;
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)GetValue(TextDecorationsProperty); }
set { 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); }
}
public OutlinedTextBlock()
{
UpdatePen();
TextDecorations = new TextDecorationCollection();
}
protected override void OnRender(DrawingContext drawingContext)
{
EnsureGeometry();
drawingContext.DrawGeometry(Fill, null, _TextGeometry);
if (StrokePosition == StrokePosition.Outside)
{
drawingContext.PushClip(_clipGeometry);
}
else if (StrokePosition == StrokePosition.Inside)
{
drawingContext.PushClip(_TextGeometry);
}
drawingContext.DrawGeometry(null, _Pen, _TextGeometry);
if (StrokePosition == StrokePosition.Outside || StrokePosition == StrokePosition.Inside)
{
drawingContext.Pop();
}
}
protected override Size MeasureOverride(Size availableSize)
{
EnsureFormattedText();
// constrain the formatted text according to the available size
double w = availableSize.Width;
double h = availableSize.Height;
// 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
_FormattedText.MaxTextWidth = Math.Min(3579139, w);
_FormattedText.MaxTextHeight = Math.Max(0.0001d, h);
// return the desired size
return new Size(Math.Ceiling(_FormattedText.Width), Math.Ceiling(_FormattedText.Height));
}
protected override Size ArrangeOverride(Size finalSize)
{
EnsureFormattedText();
// update the formatted text with the final size
_FormattedText.MaxTextWidth = finalSize.Width;
_FormattedText.MaxTextHeight = Math.Max(0.0001d, finalSize.Height);
// need to re-generate the geometry now that the dimensions have changed
_TextGeometry = null;
UpdatePen();
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 (_FormattedText != null)
{
return;
}
_FormattedText = new FormattedText(
Text ?? "",
CultureInfo.CurrentUICulture,
FlowDirection,
new Typeface(FontFamily, FontStyle, FontWeight, FontStretch),
FontSize,
Brushes.Black);
UpdateFormattedText();
}
private void UpdateFormattedText()
{
if (_FormattedText == null)
{
return;
}
_FormattedText.MaxLineCount = TextWrapping == TextWrapping.NoWrap ? 1 : int.MaxValue;
_FormattedText.TextAlignment = TextAlignment;
_FormattedText.Trimming = TextTrimming;
_FormattedText.SetFontSize(FontSize);
_FormattedText.SetFontStyle(FontStyle);
_FormattedText.SetFontWeight(FontWeight);
_FormattedText.SetFontFamily(FontFamily);
_FormattedText.SetFontStretch(FontStretch);
_FormattedText.SetTextDecorations(TextDecorations);
}
private void EnsureGeometry()
{
if (_TextGeometry != null)
{
return;
}
EnsureFormattedText();
_TextGeometry = _FormattedText.BuildGeometry(new Point(0, 0));
if (StrokePosition == StrokePosition.Outside)
{
var boundsGeo = new RectangleGeometry(new Rect(0, 0, ActualWidth, ActualHeight));
_clipGeometry = Geometry.Combine(boundsGeo, _TextGeometry, GeometryCombineMode.Exclude, null);
}
}
}
}
Usege:
<Grid Margin="12" Background="Bisque">
<local:OutlinedTextBlock Stroke="Red"
ClipToBounds="False"
FontSize="56"
Fill="Transparent"
StrokePosition="Inside"
StrokeThickness="1" Text=" abc">
</local:OutlinedTextBlock>
</Grid>