C#实现图片切割的方法

public class ImageManager
{
  /// <summary>
  /// 图像切割
  /// </summary>
  /// <param name="url">图像文件名称</param>
  /// <param name="width">切割后图像宽度</param>
  /// <param name="height">切割后图像高度</param>
  /// <param name="savePath">切割后图像文件保存路径</param>
  /// <param name="fileExt">切割后图像文件扩展名</param>
  public static void Cut(string url, int width, int height,string savePath,string fileExt,string logofile)
  {
   Bitmap bitmap = new Bitmap(url);
   Decimal MaxRow = Math.Ceiling((Decimal)bitmap.Height / height);
   Decimal MaxColumn = Math.Ceiling((decimal)bitmap.Width / width);
   for (decimal i = 0; i < MaxRow; i++)
   {
    for (decimal j = 0; j < MaxColumn; j++)
    {
     string filename = i.ToString() + "," + j.ToString() + "." + fileExt;
     Bitmap bmp = new Bitmap(width, height);
     for (int offsetX = 0; offsetX < width; offsetX++)
     {
      for (int offsetY = 0; offsetY < height; offsetY++)
      {
       if (((j * width + offsetX) < bitmap.Width) && ((i * height + offsetY) < bitmap.Height))
       {
        bmp.SetPixel(offsetX, offsetY, bitmap.GetPixel((int)(j * width + offsetX), (int)(i * height + offsetY)));
       }
      }
     }
     Graphics g = Graphics.FromImage(bmp);
     g.DrawString("我们", new Font("黑体", 20), new SolidBrush(Color.FromArgb(70, Color.WhiteSmoke)), 60, height/2);//加水印
     ImageFormat format = ImageFormat.Png;
     switch (fileExt.ToLower())
     {
      case "png":
       format = ImageFormat.Png;
       break;
      case "bmp":
       format = ImageFormat.Bmp;
       break;
      case "gif":
       format = ImageFormat.Gif;
       break;
     }
     bmp.Save(savePath+"//" + filename,format);
    }
   }
  }
}