Example of scrolling web page screenshot function implemented by C#

using System;
using ;
using ;
using ;
using ;
using ;
using ;
using ;
namespace WindowsFormsApplication1
{
  public partial class Form1 : Form
  {
    private int _currentWidth = 1024;
    private Bitmap _currentBitmap = null;
    public Form1()
    {
      InitializeComponent();
    }
private void button1_Click(object sender, EventArgs e)
{
  if ( == null)
    return;
  try
  {
    int width = _currentWidth;
    int height = ;
     = width;
     = height;
    _currentBitmap = new Bitmap(width, height);
    ();
    (_currentBitmap, new Rectangle(0, 0, width, height));
     = _currentBitmap;
  }
  catch (Exception ex)
  {
    ((), "Escaped an error", , );
  }
}
  }
}