ASP.NET软件开发_ 旋转的可视验证码图象_源码

 

   /// <summary>
    /// 旋转的可视验证码图象
    /// </summary>
    public class VlidationCode
    {
        public enum RandomStringMode
        {
            /// <summary>
            /// 小写字母
            /// </summary>
            LowerLetter,
            /// <summary>
            /// 大写字母
            /// </summary>
            UpperLetter,
            /// <summary>
            /// 混合大小写字母
            /// </summary>
            Letter,
            /// <summary>
            /// 数字
            /// </summary>
            Digital,
            /// <summary>
            /// 混合数字与大小字母
            /// </summary>
            Mix
        }

        public static string GenerateRandomString(int length, RandomStringMode mode)
        {
            string rndStr = string.Empty;
            if (length == 0)
                return rndStr;

            //以数组方式候选字符，可以更方便的剔除不要的字符，如数字 0 与字母 o
            char[] digitals = new char[10] { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };
            char[] lowerLetters = new char[26] {
                'a', 'b', 'c', 'd', 'e', 'f', 'g',
                'h', 'i', 'j', 'k', 'l', 'm', 'n',
                'o', 'p', 'q', 'r', 's', 't',
                'u', 'v', 'w', 'x', 'y', 'z' };
            char[] upperLetters = new char[26] {
                'A', 'B', 'C', 'D', 'E', 'F', 'G',
                'H', 'I', 'J', 'K', 'L', 'M', 'N',
                'O', 'P', 'Q', 'R', 'S', 'T',
                'U', 'V', 'W', 'X', 'Y', 'Z' };
            char[] letters = new char[52]{
                'a', 'b', 'c', 'd', 'e', 'f', 'g',
                'h', 'i', 'j', 'k', 'l', 'm', 'n',
                'o', 'p', 'q', 'r', 's', 't',
                'u', 'v', 'w', 'x', 'y', 'z',
                'A', 'B', 'C', 'D', 'E', 'F', 'G',
                'H', 'I', 'J', 'K', 'L', 'M', 'N',
                'O', 'P', 'Q', 'R', 'S', 'T',
                'U', 'V', 'W', 'X', 'Y', 'Z' };
            char[] mix = new char[62]{
                '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
                'a', 'b', 'c', 'd', 'e', 'f', 'g',
                'h', 'i', 'j', 'k', 'l', 'm', 'n',
                'o', 'p', 'q', 'r', 's', 't',
                'u', 'v', 'w', 'x', 'y', 'z',
                'A', 'B', 'C', 'D', 'E', 'F', 'G',
                'H', 'I', 'J', 'K', 'L', 'M', 'N',
                'O', 'P', 'Q', 'R', 'S', 'T',
                'U', 'V', 'W', 'X', 'Y', 'Z' };

            int[] range = new int[2] { 0, 0 };
            Random random = new Random();

            switch (mode)
            {
                case RandomStringMode.Digital:
                    for (int i = 0; i < length; ++i)
                        rndStr += digitals[random.Next(0, digitals.Length)];
                    break;

                case RandomStringMode.LowerLetter:
                    for (int i = 0; i < length; ++i)
                        rndStr += lowerLetters[random.Next(0, lowerLetters.Length)];
                    break;

                case RandomStringMode.UpperLetter:
                    for (int i = 0; i < length; ++i)
                        rndStr += upperLetters[random.Next(0, upperLetters.Length)];
                    break;

                case RandomStringMode.Letter:
                    for (int i = 0; i < length; ++i)
                        rndStr += letters[random.Next(0, letters.Length)];
                    break;

                default:
                    for (int i = 0; i < length; ++i)
                        rndStr += mix[random.Next(0, mix.Length)];
                    break;
            }

            return rndStr;
        }

        public static void ShowCode(int i)
        {
             ShowValidationCode(ref i, 4, 20, RandomStringMode.UpperLetter, Color.Gold, Color.WhiteSmoke);
        }
        /// <summary>
        /// 显示验证码
        /// </summary>
        /// <param name="seed">随机数辅助种子</param>
        /// <param name="strLen">验证码字符长度</param>
        /// <param name="fontSize">字体大小</param>
        /// <param name="mode">随机字符模式</param>
        /// <param name="clrFont">字体颜色</param>
        /// <param name="clrBg">背景颜色</param>
        public static void ShowValidationCode(ref int seed, int strLen, int fontSize, RandomStringMode mode, Color clrFont, Color clrBg)
        {
            int tmpSeed;
            unchecked
            {
                tmpSeed = (int)(seed * DateTime.Now.Ticks);
                ++seed;
            }
            Random rnd = new Random(tmpSeed);

            string text = GenerateRandomString(strLen, mode);
            int height = fontSize * 2;
            // 因为字体旋转后每个字体所占宽度会所有加大，所以要加一点补偿宽度
            int width = fontSize * text.Length + fontSize / (text.Length - 2);
            Bitmap bmp = new Bitmap(width, height);

            Graphics graphics = Graphics.FromImage(bmp);
            Font font = new Font("Courier New", fontSize, FontStyle.Bold);
            Brush brush = new SolidBrush(clrFont);
            Brush brushBg = new SolidBrush(clrBg);
            graphics.FillRectangle(brushBg, 0, 0, width, height);
            Bitmap tmpBmp = new Bitmap(height, height);
            Graphics tmpGph = null;
            int degree = 40;
            Point tmpPoint = new Point();
            for (int i = 0; i < text.Length; i++)
            {
                tmpBmp = new Bitmap(height, height);
                tmpGph = Graphics.FromImage(tmpBmp);
               // tmpGph.TextRenderingHint = System.Drawing.Text.TextRenderingHint.SingleBitPerPixelGridFit;
               // 不填充底色，文字 ClearType 效果不见了，why?!
               // tmpGph.FillRectangle(brushBg, 0, 0, tmpBmp.Width, tmpBmp.Height);
                degree = rnd.Next(20, 51); // [20, 50]随机角度
                if (rnd.Next(0, 2) == 0)
                {
                    tmpPoint.X = 12; // 调整文本坐标以适应旋转后的图象
                    tmpPoint.Y = -6;
                }
                else
                {
                    degree = ~degree + 1; // 逆时针旋转
                    tmpPoint.X = -10;
                    tmpPoint.Y = 6;
                }

                tmpGph.RotateTransform(degree);
                tmpGph.DrawString(text[i].ToString(), font, brush, tmpPoint);
                graphics.DrawImage(tmpBmp, i * fontSize, 0); // 拼接图象
            }
           
            //输出图象
            System.IO.MemoryStream memoryStream = new System.IO.MemoryStream();
            bmp.Save(memoryStream, System.Drawing.Imaging.ImageFormat.Gif);
            HttpContext.Current.Response.Cache.SetCacheability(HttpCacheability.NoCache);
            HttpContext.Current.Response.ClearContent();
            HttpContext.Current.Response.ContentType = "image/gif";
            HttpContext.Current.Response.BinaryWrite(memoryStream.ToArray());
            HttpContext.Current.Response.End();

            //释放资源
            font.Dispose();
            brush.Dispose();
            brushBg.Dispose();
            tmpGph.Dispose();
            tmpBmp.Dispose();
            graphics.Dispose();
            bmp.Dispose();
            memoryStream.Dispose();
        }
    }