Log4Net: TextBoxBaseAppender

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using log4net.Appender;
using System.Windows.Forms;
using log4net.Core;
using log4net.Layout;

namespace UI
{
     ///   <summary>
     ///  Usage:
     ///      log4net.Config.BasicConfigurator.Configure();
     ///      var logPattern = "%date [%thread] %-5level %logger !%M - %message%newline";
     ///      var logAppender = new TextBoxBaseAppender()
     ///      {
     ///          TextBox = this.textBox2,
     ///          Layout = new PatternLayout(logPattern)
     ///      };
     ///      
     ///      ((log4net.Repository.Hierarchy.Hierarchy)log4net.LogManager.GetLoggerRepository()).Root.AddAppender(logAppender);
     ///   </summary>
     public  class TextBoxBaseAppender : AppenderSkeleton
    {
         public TextBoxBase TextBox {  get;  set; }

         public TextBoxBaseAppender()
        {
        }

         protected  override  void Append(LoggingEvent loggingEvent)
        {
             if ( this.TextBox ==  null)
            {
                 return;
            }

             if(! this.TextBox.IsHandleCreated)
            {
                 return;
            }

             if( this.TextBox.IsDisposed)
            {
                 return;
            }

             var patternLayout =  this.Layout  as PatternLayout;

             var str =  string.Empty;
             if (patternLayout !=  null)
            {
                str = patternLayout.Format(loggingEvent);

                 if (loggingEvent.ExceptionObject !=  null)
                {
                    str += loggingEvent.ExceptionObject.ToString() + Environment.NewLine;
                }
            }
             else
            {
                str = loggingEvent.LoggerName +  " - " + loggingEvent.RenderedMessage + Environment.NewLine;
            }

             if (! this.TextBox.InvokeRequired)
            {
                 this.TextBox.AppendText(str);
            }
             else
            {
                 this.TextBox.BeginInvoke((MethodInvoker) delegate
                {
                     if (! this.TextBox.IsHandleCreated)
                    {
                         return;
                    }

                     if ( this.TextBox.IsDisposed)
                    {
                         return;
                    }
                     this.TextBox.AppendText(str);
                });
            }
        }
    }
}