How to bind a TextBlock to a resource containing formatted text?

Question

I have a TextBlock in my WPF window.

 
     Some formatted text.
 

When it is r

Answer 1

I ended up needing to do this in my application and had to support many of the markup possible normally in TextBlock inlines, so I took Wallstreet Programmer's answer above (which works beautifully and is much less complicated than most other answers I found on this topic) and expanded on it. I figure someone else might find this useful.

I haven't thoroughly tested this with ALL the tags yet, but every one I've tested has worked like a charm. I also suspect it's not the fastest code in the world, but my own testing with several thousand formatted messages in a ListView seemed surprisingly zippy. YMMV. Code is below:

XAML:

C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Media;

namespace FormatTest
{

public static class FormattedTextBehavior
{
    public class TextPart
    {
        public String mType = String.Empty;
        public Inline mInline = null;
        public InlineCollection mChildren = null;

        public TextPart() {}
        public TextPart(String t, Inline inline, InlineCollection col)
        {
            mType = t;
            mInline = inline;
            mChildren = col;
        }
    }

    private static Regex mRegex = new Regex(@"<(?/?[^>]*)>", RegexOptions.Compiled | RegexOptions.IgnoreCase);
    private static Regex mSpanRegex = new Regex("(?[^\\s=]+)=\"(?[^\\s\"]*)\"", RegexOptions.Compiled | RegexOptions.IgnoreCase);

    public static string GetFormattedText(DependencyObject obj)
    {
        return (string)obj.GetValue(FormattedTextProperty);
    }

    public static void SetFormattedText(DependencyObject obj, string value)
    {
        obj.SetValue(FormattedTextProperty, value);
    }

    public static readonly DependencyProperty FormattedTextProperty =
        DependencyProperty.RegisterAttached("FormattedText",
                                            typeof(string),
                                            typeof(FormattedTextBehavior),
                                            new UIPropertyMetadata("", FormattedTextChanged));

    private static void FormattedTextChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
    {
        TextBlock textBlock = sender as TextBlock;
        FormatText(e.NewValue as string, new TextPart("TextBlock", null, textBlock.Inlines));
    }

    public static void FormatText(String s, TextPart root)
    {
        int len = s.Length;
        int lastIdx = 0;
        List parts = new List();
        parts.Add(root);
        Match m = mRegex.Match(s);
        while (m.Success)
        {
            String tag = m.Result("${Span}");
            if (tag.StartsWith("/"))
            {
                String prevStr = s.Substring(lastIdx, m.Index - lastIdx);
                TextPart part = parts.Last();
                if (!String.IsNullOrEmpty(prevStr))
                {
                    if (part.mChildren != null)
                    {
                        part.mChildren.Add(new Run(prevStr));
                    }
                    else if (part.mInline is Run)
                    {
                        (part.mInline as Run).Text = prevStr;
                    }
                }
                if (!tag.Substring(1).Equals(part.mType, StringComparison.InvariantCultureIgnoreCase))
                {
                    Logger.LogD("Mismatched End Tag '" + tag.Substring(1) + "' (expected ) at position " + m.Index.ToString() + " in String '" + s + "'");
                }
                if (parts.Count > 1)
                {
                    parts.RemoveAt(parts.Count - 1);
                    TextPart parentPart = parts.Last();
                    if (parentPart.mChildren != null)
                    {
                        parentPart.mChildren.Add(part.mInline);
                    }
                }
            }
            else
            {
                TextPart prevPart = parts.Last();
                String prevStr = s.Substring(lastIdx, m.Index - lastIdx);
                if (!String.IsNullOrEmpty(prevStr))
                {
                    if (prevPart.mChildren != null)
                    {
                        prevPart.mChildren.Add(new Run(prevStr));
                    }
                    else if (prevPart.mInline is Run)
                    {
                        (prevPart.mInline as Run).Text = prevStr;
                    }
                }

                bool hasAttributes = false;
                TextPart part = new TextPart();
                if (tag.StartsWith("bold", StringComparison.InvariantCultureIgnoreCase))
                {
                    part.mType = "BOLD";
                    part.mInline = new Bold();
                    part.mChildren = (part.mInline as Bold).Inlines;
                }
                else if (tag.StartsWith("underline", StringComparison.InvariantCultureIgnoreCase))
                {
                    part.mType = "UNDERLINE";
                    part.mInline = new Underline();
                    part.mChildren = (part.mInline as Underline).Inlines;
                }
                else if (tag.StartsWith("italic", StringComparison.InvariantCultureIgnoreCase))
                {
                    part.mType = "ITALIC";
                    part.mInline = new Italic();
                    part.mChildren = (part.mInline as Italic).Inlines;
                }
                else if (tag.StartsWith("linebreak", StringComparison.InvariantCultureIgnoreCase))
                {
                    part.mType = "LINEBREAK";
                    part.mInline = new LineBreak();
                }
                else if (tag.StartsWith("span", StringComparison.InvariantCultureIgnoreCase))
                {
                    hasAttributes = true;
                    part.mType = "SPAN";
                    part.mInline = new Span();
                    part.mChildren = (part.mInline as Span).Inlines;
                }
                else if (tag.StartsWith("run", StringComparison.InvariantCultureIgnoreCase))
                {
                    hasAttributes = true;
                    part.mType = "RUN";
                    part.mInline = new Run();
                }
                else if (tag.StartsWith("hyperlink", StringComparison.InvariantCultureIgnoreCase))
                {
                    hasAttributes = true;
                    part.mType = "HYPERLINK";
                    part.mInline = new Hyperlink();
                    part.mChildren = (part.mInline as Hyperlink).Inlines;
                }

                if (hasAttributes && part.mInline != null)
                {
                    Match m2 = mSpanRegex.Match(tag);
                    while (m2.Success)
                    {
                        String key = m2.Result("${Key}");
                        String val = m2.Result("${Val}");
                        if (key.Equals("FontWeight", StringComparison.InvariantCultureIgnoreCase))
                        {
                            FontWeight fw = FontWeights.Normal;
                            try
                            {
                                fw = (FontWeight)new FontWeightConverter().ConvertFromString(val);
                            }
                            catch (Exception)
                            {
                                fw = FontWeights.Normal;
                            }
                            part.mInline.FontWeight = fw;
                        }
                        else if (key.Equals("FontSize", StringComparison.InvariantCultureIgnoreCase))
                        {
                            double fs = part.mInline.FontSize;
                            if (Double.TryParse(val, out fs))
                            {
                                part.mInline.FontSize = fs;
                            }
                        }
                        else if (key.Equals("FontStretch", StringComparison.InvariantCultureIgnoreCase))
                        {
                            FontStretch fs = FontStretches.Normal;
                            try
                            {
                                fs = (FontStretch)new FontStretchConverter().ConvertFromString(val);
                            }
                            catch (Exception)
                            {
                                fs = FontStretches.Normal;
                            }
                            part.mInline.FontStretch = fs;
                        }
                        else if (key.Equals("FontStyle", StringComparison.InvariantCultureIgnoreCase))
                        {
                            FontStyle fs = FontStyles.Normal;
                            try
                            {
                                fs = (FontStyle)new FontStyleConverter().ConvertFromString(val);
                            }
                            catch (Exception)
                            {
                                fs = FontStyles.Normal;
                            }
                            part.mInline.FontStyle = fs;
                        }
                        else if (key.Equals("FontFamily", StringComparison.InvariantCultureIgnoreCase))
                        {
                            if (!String.IsNullOrEmpty(val))
                            {
                                FontFamily ff = new FontFamily(val);
                                if (Fonts.SystemFontFamilies.Contains(ff))
                                {
                                    part.mInline.FontFamily = ff;
                                }
                            }
                        }
                        else if (key.Equals("Background", StringComparison.InvariantCultureIgnoreCase))
                        {
                            Brush b = part.mInline.Background;
                            try
                            {
                                b = (Brush)new BrushConverter().ConvertFromString(val);
                            }
                            catch (Exception)
                            {
                                b = part.mInline.Background;
                            }
                            part.mInline.Background = b;
                        }
                        else if (key.Equals("Foreground", StringComparison.InvariantCultureIgnoreCase))
                        {
                            Brush b = part.mInline.Foreground;
                            try
                            {
                                b = (Brush)new BrushConverter().ConvertFromString(val);
                            }
                            catch (Exception)
                            {
                                b = part.mInline.Foreground;
                            }
                            part.mInline.Foreground = b;
                        }
                        else if (key.Equals("ToolTip", StringComparison.InvariantCultureIgnoreCase))
                        {
                            part.mInline.ToolTip = val;
                        }
                        else if (key.Equals("Text", StringComparison.InvariantCultureIgnoreCase) && part.mInline is Run)
                        {
                            (part.mInline as Run).Text = val;
                        }
                        else if (key.Equals("NavigateUri", StringComparison.InvariantCultureIgnoreCase) && part.mInline is Hyperlink)
                        {
                            (part.mInline as Hyperlink).NavigateUri = new Uri(val);
                        }
                        m2 = m2.NextMatch();
                    }
                }

                if (part.mInline != null)
                {
                    if (tag.TrimEnd().EndsWith("/"))
                    {
                        if (prevPart.mChildren != null)
                        {
                            prevPart.mChildren.Add(part.mInline);
                        }
                    }
                    else
                    {
                        parts.Add(part);
                    }
                }
            }
            lastIdx = m.Index + m.Length;
            m = m.NextMatch();
        }
        if (lastIdx < (len - 1))
        {
            root.mChildren.Add(new Run(s.Substring(lastIdx)));
        }
    }
}

}