Rendering HTML in Silverlight

Whilst not an obviously useful requirement, converting Rich Text to and from HTML would be very useful for applications such as Forums, web CMS's etc, the problem is getting RichText into our Silverlight application.

Using the Liquid RichTextBox we can enter RichText into a Silverlight application and then retrieve the input as XML and convert it (roughly) to HTML.

Whilst it seems like a simple task there are lots of things to take into account when trying to convert such as class/style names, bulleted lists etc.  The methods presented here in this static class were quickly nocked up in a few hours and can still be improved.

using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Windows;
using System.Windows.Media;
using System.Xml;

namespace Liquid.Components
{
    public class Html
    {
        #region Public Methods

        public static string[] ConvertRichTextToHTML(string richTextXML)
        {
            Dictionary<string, RichTextBoxStyle> styleList = new Dictionary<string, RichTextBoxStyle>();
            RichTextBoxStyle style;
            XmlReader reader;
            string styleID;
            string temp;
            string tag;
            string optional;
            StringBuilder html = new StringBuilder();
            StringBuilder styles = new StringBuilder();
            

            reader = XmlReader.Create(new StringReader(richTextXML));
            reader.Read();

            while (reader.Read())
            {
                if (reader.NodeType == XmlNodeType.Element)
                {
                    temp = reader.Name.ToLower();

                    if (temp == RichTextBox.StyleElement)
                    {
                        style = new RichTextBoxStyle(reader);
                        styleList.Add(style.ID, style);

                        if (IsStyleAHeading(style.ID.ToLower()))
                        {
                            tag = "";
                        }
                        else
                        {
                            tag = ".";
                        }

                        styles.Append(tag + style.ID + " {");

                        styles.Append("font-family:" + style.Family + "; ");
                        styles.Append("font-size:" + style.Size.ToString() + "px; ");
                        styles.Append("text-align:" + style.Alignment.ToString() + "; ");
                        styles.Append("color:#" + ((SolidColorBrush)style.Foreground).Color.ToString().Substring(3) + "; ");

                        if (style.Weight == FontWeights.Bold)
                        {
                            styles.Append("font-weight:bold; ");
                        }
                        if (style.Decorations == TextDecorations.Underline)
                        {
                            styles.Append("text-decoration:underline; ");
                        }
                        if (style.Style == FontStyles.Italic)
                        {
                            styles.Append("font-style:italic; ");
                        }
                        if (style.Special == RichTextSpecialFormatting.Subscript)
                        {
                        }
                        else if (style.Special == RichTextSpecialFormatting.Superscript)
                        {
                        }

                        styles.Append(" }\r\n");
                    }
                    else if (temp == RichTextBox.TextElement)
                    {
                        styleID = reader.GetAttribute("Style");
                        reader.Read();

                        optional = "";
                        if(IsStyleAHeading(styleID.ToLower()))
                        {
                            tag = styleID.ToLower();
                        }
                        else if (styleList[styleID].Link.Length > 0)
                        {
                            tag = "a";
                            optional = " href='" + styleList[styleID].Link + "' class='" + styleID + "'";
                        }
                        else
                        {
                            tag = "span";
                            optional = " class='" + styleID + "'";
                        }

                        if (reader.NodeType == XmlNodeType.CDATA)
                        {
                            html.Append("<" + tag + optional + ">" + reader.Value + "</" + tag + ">");
                        }
                    }
                    else if (temp == RichTextBox.NewlineElement)
                    {
                        reader.Read();
                        html.Append("<br />");
                    }
                    else if (temp == RichTextBox.XamlElement)
                    {
                        continue;
                    }
                }
            }

            reader.Close();

            return new string[] { styles.ToString(), html.ToString() };
        }

        public static string ConvertRichTextToHTMLDocument(string richTextXML)
        {
            string[] temp = ConvertRichTextToHTML(richTextXML);

            return "<html><head><style>" + temp[0] + "</style></head><body>" + temp[1] + "</body></html>";
        }

        #endregion

        #region Private Methods

        private static bool IsStyleAHeading(string styleID)
        {
            return (styleID == "h1" || styleID == "h2" || styleID == "h3" || styleID == "h4");
        }

        #endregion
    }
}


The conversion using the above class does a very basic translation to HTML, and if you run the example you will see plenty of room for improvement.  In terms of converting from HTML to RichText, well, that article is on the way...

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