WPF 字体描边的实现方式

原文: WPF 字体描边的实现方式

        <local:TextPath x:Name="PathEdge"
		                Fill="Red"
		                Stroke="Yellow"
		                StrokeThickness="2"
		                FontFamily="Ariel"
		                FontSize="72"
		                FontWeight="Bold"
		                Text="This is a Test of Outline Text"/>

using System;
using System.ComponentModel;
using System.Threading;
using System.Windows;
using System.Windows.Documents;
using System.Windows.Media;
using System.Windows.Shapes;

namespace WpfOutlineFontSample
{
	/// <summary>
	/// This class generates a Geometry from a block of text in a specific font, weight, etc.
	/// and renders it to WPF as a shape.
	/// </summary>
	public class TextPath : Shape
	{
		private Geometry _textGeometry;

		#region Dependency Properties
		public static readonly DependencyProperty FontFamilyProperty = TextElement.FontFamilyProperty.AddOwner(typeof(TextPath),
													 new FrameworkPropertyMetadata(SystemFonts.MessageFontFamily,
															 FrameworkPropertyMetadataOptions.AffectsRender | FrameworkPropertyMetadataOptions.AffectsMeasure | FrameworkPropertyMetadataOptions.Inherits,
															 OnPropertyChanged));
		[Bindable(true), Category("Appearance")]
		[Localizability(LocalizationCategory.Font)]
		[TypeConverter(typeof(FontFamilyConverter))]
		public FontFamily FontFamily { get { return (FontFamily)GetValue(FontFamilyProperty); } set { SetValue(FontFamilyProperty, value); } }

		public static readonly DependencyProperty FontSizeProperty = TextElement.FontSizeProperty.AddOwner(typeof(TextPath),
														new FrameworkPropertyMetadata(SystemFonts.MessageFontSize,
															 FrameworkPropertyMetadataOptions.AffectsRender | FrameworkPropertyMetadataOptions.AffectsMeasure,
															 OnPropertyChanged));
		[Bindable(true), Category("Appearance")]
		[TypeConverter(typeof(FontSizeConverter))]
		[Localizability(LocalizationCategory.None)]
		public double FontSize { get { return (double)GetValue(FontSizeProperty); } set { SetValue(FontSizeProperty, value); } }

		public static readonly DependencyProperty FontStretchProperty = TextElement.FontStretchProperty.AddOwner(typeof(TextPath),
													 new FrameworkPropertyMetadata(TextElement.FontStretchProperty.DefaultMetadata.DefaultValue,
															 FrameworkPropertyMetadataOptions.AffectsRender | FrameworkPropertyMetadataOptions.AffectsMeasure | FrameworkPropertyMetadataOptions.Inherits,
															 OnPropertyChanged));
		[Bindable(true), Category("Appearance")]
		[TypeConverter(typeof(FontStretchConverter))]
		public FontStretch FontStretch { get { return (FontStretch)GetValue(FontStretchProperty); } set { SetValue(FontStretchProperty, value); } }

		public static readonly DependencyProperty FontStyleProperty = TextElement.FontStyleProperty.AddOwner(typeof(TextPath),
													 new FrameworkPropertyMetadata(SystemFonts.MessageFontStyle,
															 FrameworkPropertyMetadataOptions.AffectsRender | FrameworkPropertyMetadataOptions.AffectsMeasure | FrameworkPropertyMetadataOptions.Inherits,
															 OnPropertyChanged));
		[Bindable(true), Category("Appearance")]
		[TypeConverter(typeof(FontStyleConverter))]
		public FontStyle FontStyle { get { return (FontStyle)GetValue(FontStyleProperty); } set { SetValue(FontStyleProperty, value); } }

		public static readonly DependencyProperty FontWeightProperty = TextElement.FontWeightProperty.AddOwner(typeof(TextPath),
													 new FrameworkPropertyMetadata(SystemFonts.MessageFontWeight,
															 FrameworkPropertyMetadataOptions.AffectsRender | FrameworkPropertyMetadataOptions.AffectsMeasure | FrameworkPropertyMetadataOptions.Inherits,
															 OnPropertyChanged));
		[Bindable(true), Category("Appearance")]
		[TypeConverter(typeof(FontWeightConverter))]
		public FontWeight FontWeight { get { return (FontWeight)GetValue(FontWeightProperty); } set { SetValue(FontWeightProperty, value); } }

		public static readonly DependencyProperty OriginPointProperty =
										DependencyProperty.Register("Origin", typeof(Point), typeof(TextPath),
												new FrameworkPropertyMetadata(new Point(0, 0),
														FrameworkPropertyMetadataOptions.AffectsRender | FrameworkPropertyMetadataOptions.AffectsMeasure,
															 OnPropertyChanged));
		[Bindable(true), Category("Appearance")]
		[TypeConverter(typeof(PointConverter))]
		public Point Origin { get { return (Point)GetValue(OriginPointProperty); } set { SetValue(OriginPointProperty, value); } }

		public static readonly DependencyProperty TextProperty =
										DependencyProperty.Register("Text", typeof(string), typeof(TextPath),
												new FrameworkPropertyMetadata(string.Empty,
														FrameworkPropertyMetadataOptions.AffectsRender | FrameworkPropertyMetadataOptions.AffectsMeasure,
															 OnPropertyChanged));
		[Bindable(true), Category("Appearance")]
		public string Text { get { return (string)GetValue(TextProperty); } set { SetValue(TextProperty, value); } }
		#endregion

		protected override Geometry DefiningGeometry
        {
            get { return _textGeometry;}

            //_textGeometry = Geometry.Empty;//_textGeometry ;
        }

		private static void OnPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 
        {
           ((TextPath)d).CreateTextGeometry();
        }
        

		private void CreateTextGeometry()
		{
			var formattedText = new FormattedText(Text, Thread.CurrentThread.CurrentUICulture, FlowDirection.LeftToRight,
									new Typeface(FontFamily, FontStyle, FontWeight, FontStretch), FontSize, Brushes.Black);
			_textGeometry = formattedText.BuildGeometry(Origin);
		}

		protected override Size MeasureOverride(Size availableSize)
		{
			if (_textGeometry == null) CreateTextGeometry();
			if (_textGeometry.Bounds == Rect.Empty)
				return new Size(0, 0);
			// return the desired size
			return new Size(Math.Min(availableSize.Width, _textGeometry.Bounds.Width), Math.Min(availableSize.Height, _textGeometry.Bounds.Height));
		}
	}
}