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

Question

I have a TextBlock in my WPF window.

 <TextBlock>      Some <Bold>formatted</Bold> text.  </TextBlock> 

When it is rendered it looks like this,

Some formatted text.

My question is, can I bind this inline "content" to a resource in my application?

I got as far as:

Making an application resource string,

myText="Some <Bold>formatted</Bold> text." 

and the following xaml (Some code omitted for brevity)

 <Window xmlns:props="clr-namespace:MyApp.Properties">      <Window.Resources>          <props:Resources x:Key="Resources"/>      </Window.Resources>       <TextBlock x:Name="Try1"            Text="{Binding Source={StaticResource Resources} Path=myText}"/>      <TextBlock x:Name="Try2">           <Binding Source="{StaticResource Resources}" Path="myText" />      </TextBlock>  </Window> 

Try1 renders with the tags in place and not effecting formatting.

Some <Bold>formatted<Bold> text.

Try2 will not compile or render because the resource "myText" is not of type Inline but a string.

Is this seemingly simple task possible and if so how?

Answer 1

Here is my modified code for recursively format text. It handles Bold, Italic, Underline and LineBreak but can easily be extended to support more (modify the switch statement).

public static class MyBehavior {     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(MyBehavior),         new UIPropertyMetadata("", FormattedTextChanged));      static Inline Traverse(string value)     {         // Get the sections/inlines         string[] sections = SplitIntoSections(value);          // Check for grouping         if (sections.Length.Equals(1))         {             string section = sections[0];             string token; // E.g <Bold>             int tokenStart, tokenEnd; // Where the token/section starts and ends.              // Check for token             if (GetTokenInfo(section, out token, out tokenStart, out tokenEnd))             {                 // Get the content to further examination                 string content = token.Length.Equals(tokenEnd - tokenStart) ?                     null :                     section.Substring(token.Length, section.Length - 1 - token.Length * 2);                  switch (token)                 {                     case "<Bold>":                         return new Bold(Traverse(content));                     case "<Italic>":                         return new Italic(Traverse(content));                     case "<Underline>":                         return new Underline(Traverse(content));                     case "<LineBreak/>":                         return new LineBreak();                     default:                         return new Run(section);                 }             }             else return new Run(section);         }         else // Group together         {             Span span = new Span();              foreach (string section in sections)                 span.Inlines.Add(Traverse(section));              return span;         }     }      /// <summary>     /// Examines the passed string and find the first token, where it begins and where it ends.     /// </summary>     /// <param name="value">The string to examine.</param>     /// <param name="token">The found token.</param>     /// <param name="startIndex">Where the token begins.</param>     /// <param name="endIndex">Where the end-token ends.</param>     /// <returns>True if a token was found.</returns>     static bool GetTokenInfo(string value, out string token, out int startIndex, out int endIndex)     {         token = null;         endIndex = -1;          startIndex = value.IndexOf("<");         int startTokenEndIndex = value.IndexOf(">");          // No token here         if (startIndex < 0)             return false;          // No token here         if (startTokenEndIndex < 0)             return false;          token = value.Substring(startIndex, startTokenEndIndex - startIndex + 1);          // Check for closed token. E.g. <LineBreak/>         if (token.EndsWith("/>"))         {             endIndex = startIndex + token.Length;             return true;         }          string endToken = token.Insert(1, "/");          // Detect nesting;         int nesting = 0;         int temp_startTokenIndex = -1;         int temp_endTokenIndex = -1;         int pos = 0;         do         {             temp_startTokenIndex = value.IndexOf(token, pos);             temp_endTokenIndex = value.IndexOf(endToken, pos);              if (temp_startTokenIndex >= 0 && temp_startTokenIndex < temp_endTokenIndex)             {                 nesting++;                 pos = temp_startTokenIndex + token.Length;             }             else if (temp_endTokenIndex >= 0 && nesting > 0)             {                 nesting--;                 pos = temp_endTokenIndex + endToken.Length;             }             else // Invalid tokenized string                 return false;          } while (nesting > 0);          endIndex = pos;          return true;     }      /// <summary>     /// Splits the string into sections of tokens and regular text.     /// </summary>     /// <param name="value">The string to split.</param>     /// <returns>An array with the sections.</returns>     static string[] SplitIntoSections(string value)     {         List<string> sections = new List<string>();          while (!string.IsNullOrEmpty(value))         {             string token;             int tokenStartIndex, tokenEndIndex;              // Check if this is a token section             if (GetTokenInfo(value, out token, out tokenStartIndex, out tokenEndIndex))             {                 // Add pretext if the token isn't from the start                 if (tokenStartIndex > 0)                     sections.Add(value.Substring(0, tokenStartIndex));                  sections.Add(value.Substring(tokenStartIndex, tokenEndIndex - tokenStartIndex));                 value = value.Substring(tokenEndIndex); // Trim away             }             else             { // No tokens, just add the text                 sections.Add(value);                 value = null;             }         }          return sections.ToArray();     }      private static void FormattedTextChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)     {         string value = e.NewValue as string;          TextBlock textBlock = sender as TextBlock;          if (textBlock != null)             textBlock.Inlines.Add(Traverse(value));     } } 

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Edit: (proposed by Spook)

A shorter version, but requires the text to be XML-valid:

using System.Windows; using System.Windows.Controls; using System.Windows.Documents; using System.Xml;  // (...)  public static class TextBlockHelper {     #region FormattedText Attached dependency property      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(TextBlockHelper),         new UIPropertyMetadata("", FormattedTextChanged));      private static void FormattedTextChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)     {         string value = e.NewValue as string;          TextBlock textBlock = sender as TextBlock;          if (textBlock != null)         {             textBlock.Inlines.Clear();             textBlock.Inlines.Add(Process(value));         }     }      #endregion      static Inline Process(string value)     {         XmlDocument doc = new XmlDocument();         doc.LoadXml(value);          Span span = new Span();         InternalProcess(span, doc.ChildNodes[0]);          return span;     }      private static void InternalProcess(Span span, XmlNode xmlNode)     {         foreach (XmlNode child in xmlNode)         {             if (child is XmlText)             {                 span.Inlines.Add(new Run(child.InnerText));             }             else if (child is XmlElement)             {                 Span spanItem = new Span();                 InternalProcess(spanItem, child);                 switch (child.Name.ToUpper())                 {                     case "B":                     case "BOLD":                         Bold bold = new Bold(spanItem);                         span.Inlines.Add(bold);                         break;                     case "I":                     case "ITALIC":                         Italic italic = new Italic(spanItem);                         span.Inlines.Add(italic);                         break;                     case "U":                     case "UNDERLINE":                         Underline underline = new Underline(spanItem);                         span.Inlines.Add(underline);                         break;                 }             }         }     } } 

And an example of usage:

<RootItem xmlns:u="clr-namespace:MyApp.Helpers">     <TextBlock u:TextBlockHelper.FormattedText="{Binding SomeProperty}" /> </RootItem> 

Answer 2

I've added hyperlink and image support to Vincents solution:

public static class FormattedTextBlock {     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(FormattedTextBlock),         new UIPropertyMetadata("", FormattedTextChanged));      static Inline Traverse(string value)     {         // Get the sections/inlines         string[] sections = SplitIntoSections(value);          // Check for grouping         if(sections.Length.Equals(1))         {             string section = sections[0];             string token; // E.g <Bold>             int tokenStart, tokenEnd; // Where the token/section starts and ends.              // Check for token             if(GetTokenInfo(section, out token, out tokenStart, out tokenEnd))             {                 // Get the content to further examination                 string content = token.Length.Equals(tokenEnd - tokenStart) ?                     null :                     section.Substring(token.Length, section.Length - 1 - token.Length * 2);                  switch(token.ToUpper())                 {                     case "<B>":                     case "<BOLD>":                         /* <b>Bold text</b> */                         return new Bold(Traverse(content));                     case "<I>":                     case "<ITALIC>":                         /* <i>Italic text</i> */                         return new Italic(Traverse(content));                     case "<U>":                     case "<UNDERLINE>":                         /* <u>Underlined text</u> */                         return new Underline(Traverse(content));                     case "<BR>":                     case "<BR/>":                     case "<LINEBREAK/>":                         /* Line 1<br/>line 2 */                         return new LineBreak();                     case "<A>":                     case "<LINK>":                         /* <a>{http://www.google.de}Google</a> */                         var start = content.IndexOf("{");                         var end = content.IndexOf("}");                         var url = content.Substring(start + 1, end - 1);                         var text = content.Substring(end + 1);                         var link = new Hyperlink();                         link.NavigateUri = new System.Uri(url);                         link.RequestNavigate += Hyperlink_RequestNavigate;                         link.Inlines.Add(text);                         return link;                     case "<IMG>":                     case "<IMAGE>":                         /* <image>pack://application:,,,/ProjectName;component/directory1/directory2/image.png</image> */                         var image = new Image();                         var bitmap = new BitmapImage(new Uri(content));                         image.Source = bitmap;                         image.Width = bitmap.Width;                         image.Height = bitmap.Height;                         var container = new InlineUIContainer();                         container.Child = image;                         return container;                     default:                         return new Run(section);                 }             }             else return new Run(section);         }         else // Group together         {             Span span = new Span();              foreach(string section in sections)                 span.Inlines.Add(Traverse(section));              return span;         }     }      static void Hyperlink_RequestNavigate(object sender, RequestNavigateEventArgs e)     {         Process.Start(e.Uri.ToString());     }      /// <summary>     /// Examines the passed string and find the first token, where it begins and where it ends.     /// </summary>     /// <param name="value">The string to examine.</param>     /// <param name="token">The found token.</param>     /// <param name="startIndex">Where the token begins.</param>     /// <param name="endIndex">Where the end-token ends.</param>     /// <returns>True if a token was found.</returns>     static bool GetTokenInfo(string value, out string token, out int startIndex, out int endIndex)     {         token = null;         endIndex = -1;          startIndex = value.IndexOf("<");         int startTokenEndIndex = value.IndexOf(">");          // No token here         if(startIndex < 0)             return false;          // No token here         if(startTokenEndIndex < 0)             return false;          token = value.Substring(startIndex, startTokenEndIndex - startIndex + 1);          // Check for closed token. E.g. <LineBreak/>         if(token.EndsWith("/>"))         {             endIndex = startIndex + token.Length;             return true;         }          string endToken = token.Insert(1, "/");          // Detect nesting;         int nesting = 0;         int temp_startTokenIndex = -1;         int temp_endTokenIndex = -1;         int pos = 0;         do         {             temp_startTokenIndex = value.IndexOf(token, pos);             temp_endTokenIndex = value.IndexOf(endToken, pos);              if(temp_startTokenIndex >= 0 && temp_startTokenIndex < temp_endTokenIndex)             {                 nesting++;                 pos = temp_startTokenIndex + token.Length;             }             else if(temp_endTokenIndex >= 0 && nesting > 0)             {                 nesting--;                 pos = temp_endTokenIndex + endToken.Length;             }             else // Invalid tokenized string                 return false;          } while(nesting > 0);          endIndex = pos;          return true;     }      /// <summary>     /// Splits the string into sections of tokens and regular text.     /// </summary>     /// <param name="value">The string to split.</param>     /// <returns>An array with the sections.</returns>     static string[] SplitIntoSections(string value)     {         List<string> sections = new List<string>();          while(!string.IsNullOrEmpty(value))         {             string token;             int tokenStartIndex, tokenEndIndex;              // Check if this is a token section             if(GetTokenInfo(value, out token, out tokenStartIndex, out tokenEndIndex))             {                 // Add pretext if the token isn't from the start                 if(tokenStartIndex > 0)                     sections.Add(value.Substring(0, tokenStartIndex));                  sections.Add(value.Substring(tokenStartIndex, tokenEndIndex - tokenStartIndex));                 value = value.Substring(tokenEndIndex); // Trim away             }             else             { // No tokens, just add the text                 sections.Add(value);                 value = null;             }         }          return sections.ToArray();     }      private static void FormattedTextChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)     {         string value = e.NewValue as string;          TextBlock textBlock = sender as TextBlock;          if(textBlock != null)             textBlock.Inlines.Add(Traverse(value));     } } 

Thanks Vincent for the great template, it works like a charm!