source: branches/PersistenceOverhaul/HeuristicLab.ExtLibs/HeuristicLab.AvalonEdit/5.0.1/AvalonEdit-5.0.1/Editing/SelectionColorizer.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 ICSharpCode.AvalonEdit.Rendering;
#if NREFACTORY
using ICSharpCode.NRefactory.Editor;
#endif

namespace ICSharpCode.AvalonEdit.Editing
{
  sealed class SelectionColorizer : ColorizingTransformer
  {
    TextArea textArea;
    
    public SelectionColorizer(TextArea textArea)
    {
      if (textArea == null)
        throw new ArgumentNullException("textArea");
      this.textArea = textArea;
    }
    
    protected override void Colorize(ITextRunConstructionContext context)
    {
      // if SelectionForeground is null, keep the existing foreground color
      if (textArea.SelectionForeground == null)
        return;
      
      int lineStartOffset = context.VisualLine.FirstDocumentLine.Offset;
      int lineEndOffset = context.VisualLine.LastDocumentLine.Offset + context.VisualLine.LastDocumentLine.TotalLength;
      
      foreach (SelectionSegment segment in textArea.Selection.Segments) {
        int segmentStart = segment.StartOffset;
        int segmentEnd = segment.EndOffset;
        if (segmentEnd <= lineStartOffset)
          continue;
        if (segmentStart >= lineEndOffset)
          continue;
        int startColumn;
        if (segmentStart < lineStartOffset)
          startColumn = 0;
        else
          startColumn = context.VisualLine.ValidateVisualColumn(segment.StartOffset, segment.StartVisualColumn, textArea.Selection.EnableVirtualSpace);
        
        int endColumn;
        if (segmentEnd > lineEndOffset)
          endColumn = textArea.Selection.EnableVirtualSpace ? int.MaxValue : context.VisualLine.VisualLengthWithEndOfLineMarker;
        else
          endColumn = context.VisualLine.ValidateVisualColumn(segment.EndOffset, segment.EndVisualColumn, textArea.Selection.EnableVirtualSpace);
        
        ChangeVisualElements(
          startColumn, endColumn,
          element => {
            element.TextRunProperties.SetForegroundBrush(textArea.SelectionForeground);
          });
      }
    }
  }
}