C# 加文字水印

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using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Drawing; using System.Drawing.Drawing2D; using System.Drawing.Imaging; using System.IO;   public class WaterMark     {         /// <summary>         /// 生成4位字母和数字的验证码图片         /// </summary>         /// <returns>验证码的字符串</returns>         //public static string GenerateImage(string username)         //{         //    return CreateImage(username);         //}           /// <summary>         /// 创建验证码图片,并将其写入内存流中         /// </summary>         /// <param name="waterText"></param>         public static string CreateImage(string waterText)         {             // 已经存在直接返回             if (File.Exists(System.AppDomain.CurrentDomain.BaseDirectory + "\\watermarks\\" + waterText + ".png"))             {                 return "/watermarks/" + waterText + ".png";             }               //验证码未设置时，不生成图片             if (waterText == null || waterText.Trim() == String.Empty)             {                 return null;             }             Bitmap img = new Bitmap(640, 640);             Graphics g = Graphics.FromImage(img);             try             {                 //生成随机生成器                 Random random = new Random();                 //清空图片背景色                 g.Clear(Color.Transparent);                 g.InterpolationMode = InterpolationMode.High; //設定高品質插值法                 g.SmoothingMode = SmoothingMode.HighQuality; //設定高品質,低速度呈現平滑程度                 g.CompositingQuality = CompositingQuality.HighQuality;                 g.TextRenderingHint = System.Drawing.Text.TextRenderingHint.AntiAlias;                 //画图片的背景噪音线                 //for (int iCount = 0; iCount < 25; iCount++)                 //{                 //    int x1 = random.Next(img.Width);                 //    int x2 = random.Next(img.Width);                 //    int y1 = random.Next(img.Height);                 //    int y2 = random.Next(img.Height);                 //    g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);                 //}                   Font font = new Font("Arial", 24, (System.Drawing.FontStyle.Bold));                 System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, img.Width, img.Height),                     Color.Black, Color.DarkRed, 1.2f, true);                   g.RotateTransform(-30);                   float xpos = 0;                 float ypos = 0;                 // 获取图片的宽和高                 int width = img.Width;                 int height = img.Height;                   // 循环打印文字水印                 for (int i = -width / 2; i < width * 1.5; i += 180)                 {                     xpos = i;                     for (int j = -height / 2; j < height * 1.5; j += 80)                     {                         ypos = j;                         g.DrawString(waterText, font, new SolidBrush(Color.FromArgb(50, 210, 210, 210)), xpos, ypos);                         //g.DrawString(CheckCode, font, brush, 2, 2);                     }                 }                                     //画图片的前景噪音点                 //for (int i = 0; i < 100; i++)                 //{                 //    int x = random.Next(img.Width);                 //    int y = random.Next(img.Height);                 //    img.SetPixel(x, y, Color.FromArgb(random.Next()));                 //}                   //画图片的边框线                 //g.DrawRectangle(new Pen(Color.Silver), 0, 0, img.Width - 1, img.Height - 1);                   System.IO.MemoryStream ms = new System.IO.MemoryStream();                 img.Save(System.AppDomain.CurrentDomain.BaseDirectory + "\\watermarks\\" + waterText + ".png", System.Drawing.Imaging.ImageFormat.Png);                 return "/watermarks/" + waterText + ".png";                   //Response.ClearContent();                 //Response.ContentType = "image/Gif";                 //Response.BinaryWrite(ms.ToArray());                 //return img;             }             catch (Exception exp)             {                 throw exp;             }             finally             {                 g.Dispose();                 img.Dispose();             }         }     }