source: branches/PersistenceOverhaul/HeuristicLab.ExtLibs/HeuristicLab.AvalonEdit/5.0.1/AvalonEdit-5.0.1/Rendering/VisualLineTextSource.cs

// 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.Diagnostics;
using System.Windows.Media.TextFormatting;

using ICSharpCode.AvalonEdit.Document;
using ICSharpCode.AvalonEdit.Utils;

namespace ICSharpCode.AvalonEdit.Rendering
{
  /// <summary>
  /// WPF TextSource implementation that creates TextRuns for a VisualLine.
  /// </summary>
  sealed class VisualLineTextSource : TextSource, ITextRunConstructionContext
  {
    public VisualLineTextSource(VisualLine visualLine)
    {
      this.VisualLine = visualLine;
    }
    
    public VisualLine VisualLine { get; private set; }
    public TextView TextView { get; set; }
    public TextDocument Document { get; set; }
    public TextRunProperties GlobalTextRunProperties { get; set; }
    
    public override TextRun GetTextRun(int textSourceCharacterIndex)
    {
      try {
        foreach (VisualLineElement element in VisualLine.Elements) {
          if (textSourceCharacterIndex >= element.VisualColumn
              && textSourceCharacterIndex < element.VisualColumn + element.VisualLength)
          {
            int relativeOffset = textSourceCharacterIndex - element.VisualColumn;
            TextRun run = element.CreateTextRun(textSourceCharacterIndex, this);
            if (run == null)
              throw new ArgumentNullException(element.GetType().Name + ".CreateTextRun");
            if (run.Length == 0)
              throw new ArgumentException("The returned TextRun must not have length 0.", element.GetType().Name + ".Length");
            if (relativeOffset + run.Length > element.VisualLength)
              throw new ArgumentException("The returned TextRun is too long.", element.GetType().Name + ".CreateTextRun");
            InlineObjectRun inlineRun = run as InlineObjectRun;
            if (inlineRun != null) {
              inlineRun.VisualLine = VisualLine;
              VisualLine.hasInlineObjects = true;
              TextView.AddInlineObject(inlineRun);
            }
            return run;
          }
        }
        if (TextView.Options.ShowEndOfLine && textSourceCharacterIndex == VisualLine.VisualLength) {
          return CreateTextRunForNewLine();
        }
        return new TextEndOfParagraph(1);
      } catch (Exception ex) {
        Debug.WriteLine(ex.ToString());
        throw;
      }
    }

    TextRun CreateTextRunForNewLine()
    {
      string newlineText = "";
      DocumentLine lastDocumentLine = VisualLine.LastDocumentLine;
      if (lastDocumentLine.DelimiterLength == 2) {
        newlineText = "¶";
      } else if (lastDocumentLine.DelimiterLength == 1) {
        char newlineChar = Document.GetCharAt(lastDocumentLine.Offset + lastDocumentLine.Length);
        if (newlineChar == '\r')
          newlineText = "\\r";
        else if (newlineChar == '\n')
          newlineText = "\\n";
        else
          newlineText = "?";
      }
      return new FormattedTextRun(new FormattedTextElement(TextView.cachedElements.GetTextForNonPrintableCharacter(newlineText, this), 0), GlobalTextRunProperties);
    }
    
    public override TextSpan<CultureSpecificCharacterBufferRange> GetPrecedingText(int textSourceCharacterIndexLimit)
    {
      try {
        foreach (VisualLineElement element in VisualLine.Elements) {
          if (textSourceCharacterIndexLimit > element.VisualColumn
              && textSourceCharacterIndexLimit <= element.VisualColumn + element.VisualLength)
          {
            TextSpan<CultureSpecificCharacterBufferRange> span = element.GetPrecedingText(textSourceCharacterIndexLimit, this);
            if (span == null)
              break;
            int relativeOffset = textSourceCharacterIndexLimit - element.VisualColumn;
            if (span.Length > relativeOffset)
              throw new ArgumentException("The returned TextSpan is too long.", element.GetType().Name + ".GetPrecedingText");
            return span;
          }
        }
        CharacterBufferRange empty = CharacterBufferRange.Empty;
        return new TextSpan<CultureSpecificCharacterBufferRange>(empty.Length, new CultureSpecificCharacterBufferRange(null, empty));
      } catch (Exception ex) {
        Debug.WriteLine(ex.ToString());
        throw;
      }
    }
    
    public override int GetTextEffectCharacterIndexFromTextSourceCharacterIndex(int textSourceCharacterIndex)
    {
      throw new NotSupportedException();
    }
    
    string cachedString;
    int cachedStringOffset;
    
    public StringSegment GetText(int offset, int length)
    {
      if (cachedString != null) {
        if (offset >= cachedStringOffset && offset + length <= cachedStringOffset + cachedString.Length) {
          return new StringSegment(cachedString, offset - cachedStringOffset, length);
        }
      }
      cachedStringOffset = offset;
      return new StringSegment(cachedString = this.Document.GetText(offset, length));
    }
  }
}