c#获取部分DRAW

//获取部分
    public class GF_GET
    {
        /// <summary>
        /// 根据坐标点获取屏幕图像
        /// </summary>
        /// <param name="x1">左上角横坐标</param>
        /// <param name="y1">左上角纵坐标</param>
        /// <param name="x2">右下角横坐标</param>
        /// <param name="y2">右下角纵坐标</param>
        /// <returns></returns>
        public static Image GetScreen(int x1, int y1, int x2, int y2)
        {
            int w = (x2 - x1);
            int h = (y2 - y1);
            Image myImage = new Bitmap(w, h);
            Graphics g = Graphics.FromImage(myImage);
            g.CopyFromScreen(new Point(x1, y1), new Point(0, 0), new Size(w, h));
            IntPtr dc1 = g.GetHdc();
            g.ReleaseHdc(dc1);
            return myImage;
        }

        /// <summary>
        /// 获取指定文件的扩展名 例:  .txt
        /// </summary>
        /// <param name="fileName">指定文件名</param>
        /// <returns>扩展名</returns>
        public static string GetFileExtName(string fileName)
        {
            if (GF_IsOk.IsStrNullOrEmpty(fileName) || fileName.IndexOf('.') <= 0)
                return "";
            
            fileName = fileName.ToLower().Trim();       

            
            return fileName.Substring(fileName.LastIndexOf('.'), fileName.Length - fileName.LastIndexOf('.'));
        }

        public static string GetSubString(string p_SrcString, int p_Length, string p_TailString)
        {
            return GetSubString(p_SrcString, 0, p_Length, p_TailString);
        }

        public static string GetUnicodeSubString(string str, int len, string p_TailString)
        {
            string result = string.Empty;// 最终返回的结果
            int byteLen = System.Text.Encoding.Default.GetByteCount(str);// 单字节字符长度
            int charLen = str.Length;// 把字符平等对待时的字符串长度
            int byteCount = 0;// 记录读取进度
            int pos = 0;// 记录截取位置
            if (byteLen > len)
            {
                for (int i = 0; i < charLen; i++)
                {
                    if (Convert.ToInt32(str.ToCharArray()[i]) > 255)// 按中文字符计算加2
                        byteCount += 2;
                    else// 按英文字符计算加1
                        byteCount += 1;
                    if (byteCount > len)// 超出时只记下上一个有效位置
                    {
                        pos = i;
                        break;
                    }
                    else if (byteCount == len)// 记下当前位置
                    {
                        pos = i + 1;
                        break;
                    }
                }

                if (pos >= 0)
                    result = str.Substring(0, pos) + p_TailString;
            }
            else
                result = str;

            return result;
        }

        /// <summary>
        /// 取指定长度的字符串
        /// </summary>
        /// <param name="p_SrcString">要检查的字符串</param>
        /// <param name="p_StartIndex">起始位置</param>
        /// <param name="p_Length">指定长度</param>
        /// <param name="p_TailString">用于替换的字符串</param>
        /// <returns>截取后的字符串</returns>
        public static string GetSubString(string p_SrcString, int p_StartIndex, int p_Length, string p_TailString)
        {
            string myResult = p_SrcString;

            Byte[] bComments = Encoding.UTF8.GetBytes(p_SrcString);
            foreach (char c in Encoding.UTF8.GetChars(bComments))
            {    //当是日文或韩文时(注:中文的范围:\u4e00 - \u9fa5, 日文在\u0800 - \u4e00, 韩文为\xAC00-\xD7A3)
                if ((c > '\u0800' && c < '\u4e00') || (c > '\xAC00' && c < '\xD7A3'))
                {
                    //if (System.Text.RegularExpressions.Regex.IsMatch(p_SrcString, "[\u0800-\u4e00]+") || System.Text.RegularExpressions.Regex.IsMatch(p_SrcString, "[\xAC00-\xD7A3]+"))
                    //当截取的起始位置超出字段串长度时
                    if (p_StartIndex >= p_SrcString.Length)
                        return "";
                    else
                        return p_SrcString.Substring(p_StartIndex,
                                                       ((p_Length + p_StartIndex) > p_SrcString.Length) ? (p_SrcString.Length - p_StartIndex) : p_Length);
                }
            }

            if (p_Length >= 0)
            {
                byte[] bsSrcString = Encoding.Default.GetBytes(p_SrcString);

                //当字符串长度大于起始位置
                if (bsSrcString.Length > p_StartIndex)
                {
                    int p_EndIndex = bsSrcString.Length;

                    //当要截取的长度在字符串的有效长度范围内
                    if (bsSrcString.Length > (p_StartIndex + p_Length))
                    {
                        p_EndIndex = p_Length + p_StartIndex;
                    }
                    else
                    {   //当不在有效范围内时,只取到字符串的结尾

                        p_Length = bsSrcString.Length - p_StartIndex;
                        p_TailString = "";
                    }

                    int nRealLength = p_Length;
                    int[] anResultFlag = new int[p_Length];
                    byte[] bsResult = null;

                    int nFlag = 0;
                    for (int i = p_StartIndex; i < p_EndIndex; i++)
                    {
                        if (bsSrcString[i] > 127)
                        {
                            nFlag++;
                            if (nFlag == 3)
                                nFlag = 1;
                        }
                        else
                            nFlag = 0;

                        anResultFlag[i] = nFlag;
                    }

                    if ((bsSrcString[p_EndIndex - 1] > 127) && (anResultFlag[p_Length - 1] == 1))
                        nRealLength = p_Length + 1;

                    bsResult = new byte[nRealLength];

                    Array.Copy(bsSrcString, p_StartIndex, bsResult, 0, nRealLength);

                    myResult = Encoding.Default.GetString(bsResult);
                    myResult = myResult + p_TailString;
                }
            }

            return myResult;
        }

        /// <summary>
        /// 获取Email HostName 例 liyangfd@gmail.com   获取出来时@gmail.com
        /// </summary>
        /// <param name="strEmail"></param>
        /// <returns></returns>
        public static string GetEmailHostName(string strEmail)
        {
            if (strEmail.IndexOf("@") < 0)
            {
                return "";
            }
            return strEmail.Substring(strEmail.LastIndexOf("@")).ToLower();
        }

        /// <summary>
        /// 返回URL中结尾的文件名
        /// </summary>        
        public static string GetFilename(string url)
        {
            if (url == null)
            {
                return "";
            }
            string[] strs1 = url.Split(new char[] { '/' });
            return strs1[strs1.Length - 1].Split(new char[] { '?' })[0];
        }


        /// <summary>
        /// 根据阿拉伯数字返回月份的名称(可更改为某种语言)
        /// </summary>    
        public static string[] Monthes
        {
            get
            {
                return new string[] { "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December" };
            }
        }