source: trunk/sources/HeuristicLab.ExtLibs/HeuristicLab.AvalonEdit/5.0.1/AvalonEdit-5.0.1/Highlighting/HtmlRichTextWriter.cs @ 13522

// Copyright (c) 2014 AlphaSierraPapa for the SharpDevelop Team
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy of this
// software and associated documentation files (the "Software"), to deal in the Software
// without restriction, including without limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
// to whom the Software is furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in all copies or
// substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.

using System;
using System.Collections.Generic;
using System.IO;
#if DOTNET4
using System.Net;
#else
using System.Web;
#endif
using System.Text;
using System.Windows;
using System.Windows.Media;
using ICSharpCode.AvalonEdit.Utils;

namespace ICSharpCode.AvalonEdit.Highlighting
{
  /// <summary>
  /// RichTextWriter implementation that produces HTML.
  /// </summary>
  class HtmlRichTextWriter : RichTextWriter
  {
    readonly TextWriter htmlWriter;
    readonly HtmlOptions options;
    Stack<string> endTagStack = new Stack<string>();
    bool spaceNeedsEscaping = true;
    bool hasSpace;
    bool needIndentation = true;
    int indentationLevel;
    
    /// <summary>
    /// Creates a new HtmlRichTextWriter instance.
    /// </summary>
    /// <param name="htmlWriter">
    /// The text writer where the raw HTML is written to.
    /// The HtmlRichTextWriter does not take ownership of the htmlWriter;
    /// disposing the HtmlRichTextWriter will not dispose the underlying htmlWriter!
    /// </param>
    /// <param name="options">Options that control the HTML output.</param>
    public HtmlRichTextWriter(TextWriter htmlWriter, HtmlOptions options = null)
    {
      if (htmlWriter == null)
        throw new ArgumentNullException("htmlWriter");
      this.htmlWriter = htmlWriter;
      this.options = options ?? new HtmlOptions();
    }
    
    /// <inheritdoc/>
    public override Encoding Encoding {
      get { return htmlWriter.Encoding; }
    }
    
    /// <inheritdoc/>
    public override void Flush()
    {
      FlushSpace(true); // next char potentially might be whitespace
      htmlWriter.Flush();
    }
    
    /// <inheritdoc/>
    protected override void Dispose(bool disposing)
    {
      if (disposing) {
        FlushSpace(true);
      }
      base.Dispose(disposing);
    }
    
    void FlushSpace(bool nextIsWhitespace)
    {
      if (hasSpace) {
        if (spaceNeedsEscaping || nextIsWhitespace)
          htmlWriter.Write("&nbsp;");
        else
          htmlWriter.Write(' ');
        hasSpace = false;
        spaceNeedsEscaping = true;
      }
    }
    
    void WriteIndentation()
    {
      if (needIndentation) {
        for (int i = 0; i < indentationLevel; i++) {
          WriteChar('\t');
        }
        needIndentation = false;
      }
    }
    
    /// <inheritdoc/>
    public override void Write(char value)
    {
      WriteIndentation();
      WriteChar(value);
    }
    
    static readonly char[] specialChars = { ' ', '\t', '\r', '\n' };
    
    void WriteChar(char c)
    {
      bool isWhitespace = char.IsWhiteSpace(c);
      FlushSpace(isWhitespace);
      switch (c) {
        case ' ':
          if (spaceNeedsEscaping)
            htmlWriter.Write("&nbsp;");
          else
            hasSpace = true;
          break;
        case '\t':
          for (int i = 0; i < options.TabSize; i++) {
            htmlWriter.Write("&nbsp;");
          }
          break;
        case '\r':
          break; // ignore; we'll write the <br/> with the following \n
        case '\n':
          htmlWriter.Write("<br/>");
          needIndentation = true;
          break;
        default:
          #if DOTNET4
          WebUtility.HtmlEncode(c.ToString(), htmlWriter);
          #else
          HttpUtility.HtmlEncode(c.ToString(), htmlWriter);
          #endif
          break;
      }
      // If we just handled a space by setting hasSpace = true,
      // we mustn't set spaceNeedsEscaping as doing so would affect our own space,
      // not just the following spaces.
      if (c != ' ') {
        // Following spaces must be escaped if c was a newline/tab;
        // and they don't need escaping if c was a normal character.
        spaceNeedsEscaping = isWhitespace;
      }
    }
    
    /// <inheritdoc/>
    public override void Write(string value)
    {
      int pos = 0;
      do {
        int endPos = value.IndexOfAny(specialChars, pos);
        if (endPos < 0) {
          WriteSimpleString(value.Substring(pos));
          return; // reached end of string
        }
        if (endPos > pos)
          WriteSimpleString(value.Substring(pos, endPos - pos));
        WriteChar(value[pos]);
        pos = endPos + 1;
      } while (pos < value.Length);
    }
    
    void WriteIndentationAndSpace()
    {
      WriteIndentation();
      FlushSpace(false);
    }
    
    void WriteSimpleString(string value)
    {
      if (value.Length == 0)
        return;
      WriteIndentationAndSpace();
      #if DOTNET4
      WebUtility.HtmlEncode(value, htmlWriter);
      #else
      HttpUtility.HtmlEncode(value, htmlWriter);
      #endif
    }
    
    /// <inheritdoc/>
    public override void Indent()
    {
      indentationLevel++;
    }
    
    /// <inheritdoc/>
    public override void Unindent()
    {
      if (indentationLevel == 0)
        throw new NotSupportedException();
      indentationLevel--;
    }
    
    /// <inheritdoc/>
    protected override void BeginUnhandledSpan()
    {
      endTagStack.Push(null);
    }
    
    /// <inheritdoc/>
    public override void EndSpan()
    {
      htmlWriter.Write(endTagStack.Pop());
    }
    
    /// <inheritdoc/>
    public override void BeginSpan(Color foregroundColor)
    {
      BeginSpan(new HighlightingColor { Foreground = new SimpleHighlightingBrush(foregroundColor) });
    }
    
    /// <inheritdoc/>
    public override void BeginSpan(FontFamily fontFamily)
    {
      BeginUnhandledSpan(); // TODO
    }
    
    /// <inheritdoc/>
    public override void BeginSpan(FontStyle fontStyle)
    {
      BeginSpan(new HighlightingColor { FontStyle = fontStyle });
    }
    
    /// <inheritdoc/>
    public override void BeginSpan(FontWeight fontWeight)
    {
      BeginSpan(new HighlightingColor { FontWeight = fontWeight });
    }
    
    /// <inheritdoc/>
    public override void BeginSpan(HighlightingColor highlightingColor)
    {
      WriteIndentationAndSpace();
      if (options.ColorNeedsSpanForStyling(highlightingColor)) {
        htmlWriter.Write("<span");
        options.WriteStyleAttributeForColor(htmlWriter, highlightingColor);
        htmlWriter.Write('>');
        endTagStack.Push("</span>");
      } else {
        endTagStack.Push(null);
      }
    }
    
    /// <inheritdoc/>
    public override void BeginHyperlinkSpan(Uri uri)
    {
      WriteIndentationAndSpace();
      #if DOTNET4
      string link = WebUtility.HtmlEncode(uri.ToString());
      #else
      string link = HttpUtility.HtmlEncode(uri.ToString());
      #endif
      htmlWriter.Write("<a href=\"" + link + "\">");
      endTagStack.Push("</a>");
    }
  }
}