source: trunk/HeuristicLab.ExtLibs/HeuristicLab.AvalonEdit/5.0.1/AvalonEdit-5.0.1/Rendering/CurrentLineHighlightRenderer.cs

// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)

using System;
using System.Windows;
using System.Windows.Media;

using ICSharpCode.AvalonEdit.Rendering;

namespace ICSharpCode.AvalonEdit.Rendering
{
  sealed class CurrentLineHighlightRenderer : IBackgroundRenderer
  {
    #region Fields
    
    int line;
    TextView textView;
    
    public static readonly Color DefaultBackground = Color.FromArgb(22, 20, 220, 224);
    public static readonly Color DefaultBorder = Color.FromArgb(52, 0, 255, 110);
    
    #endregion

    #region Properties
    
    public int Line {
      get { return this.Line; } 
      set {
        if (this.line != value) {
          this.line = value;
          this.textView.InvalidateLayer(this.Layer);
        }
      }
    }
    
    public KnownLayer Layer
    {
      get { return KnownLayer.Selection; }
    }
    
    public Brush BackgroundBrush {
      get; set;
    }
    
    public Pen BorderPen {
      get; set;
    }
    
    #endregion    
    
    public CurrentLineHighlightRenderer(TextView textView)
    {
      if (textView == null)
        throw new ArgumentNullException("textView");
      
      this.BorderPen = new Pen(new SolidColorBrush(DefaultBorder), 1);
      this.BorderPen.Freeze();
      
      this.BackgroundBrush = new SolidColorBrush(DefaultBackground);
      this.BackgroundBrush.Freeze();
      
      this.textView = textView;
      this.textView.BackgroundRenderers.Add(this);
      
      this.line = 0;
    }
    
    public void Draw(TextView textView, DrawingContext drawingContext)
    {
      if(!this.textView.Options.HighlightCurrentLine)
        return;
      
      BackgroundGeometryBuilder builder = new BackgroundGeometryBuilder();
      
      var visualLine = this.textView.GetVisualLine(line);
      if (visualLine == null) return;
      
      var linePosY = visualLine.VisualTop - this.textView.ScrollOffset.Y;
      
      builder.AddRectangle(textView, new Rect(0, linePosY, textView.ActualWidth, visualLine.Height));
      
      Geometry geometry = builder.CreateGeometry();
      if (geometry != null) {
        drawingContext.DrawGeometry(this.BackgroundBrush, this.BorderPen, geometry);
      }
    }
  }
}