C# 生成驗證碼圖片時消除鋸齒

引言

      基於生成圖片實現了一個手機號轉圖片的需求。 內容也很簡單，直接用手機號生成一個png圖片。就是為了背景透明以便其他地方調用。 有無鋸齒主要依靠一句代碼：g.TextRenderingHint= TextRenderingHint.AntiAlias;

生成圖片 

1、有鋸齒

2、無鋸齒

生成方法

string color = "#ff6633";


        System.Drawing.Bitmap image = new System.Drawing.Bitmap(170, 35);
        Graphics g = Graphics.FromImage(image);
        
        try
        {
            g.TextRenderingHint= TextRenderingHint.AntiAlias; //消除鋸齒
           
            //生成隨機生成器
            Random random = new Random();

            //清空圖片背景色
            //g.Clear(Color.Transparent);

            //畫圖片的背景噪音線
            /*for (int i = 0; i < 2; i++)
            {
                int x1 = random.Next(image.Width);
                int x2 = random.Next(image.Width);
                int y1 = random.Next(image.Height);
                int y2 = random.Next(image.Height);

                g.DrawLine(new Pen(Color.Black), x1, y1, x2, y2);
            }
            */
            System.Drawing.ColorConverter colConvert = new System.Drawing.ColorConverter();
            Color fontColor =(System.Drawing.Color)colConvert.ConvertFromString(color);
            
            Font font = new System.Drawing.Font("Arial", 18, System.Drawing.FontStyle.Bold);
            LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), fontColor, fontColor,LinearGradientMode.Horizontal);


            g.DrawString(phone, font, brush, 2, 2);
            
            //畫圖片的前景噪音點
            //for (int i = 0; i < 50; i++)
            //{
            //    int x = random.Next(image.Width);
            //    int y = random.Next(image.Height);

            //    image.SetPixel(x, y, Color.FromArgb(random.Next()));
            //}

            //畫圖片的邊框線
            //g.DrawRectangle(new Pen(Color.White), 0, 0, image.Width - 1, image.Height - 1);

            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            Color backColor = image.GetPixel(1, 1);
            image.MakeTransparent(backColor);
            image.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
            context.Response.ClearContent();
            context.Response.ContentType = "image/x-png";
            context.Response.BinaryWrite(ms.ToArray());
        }
        finally
        {
            g.Dispose();
            image.Dispose();
        }

參考資料

http://www.blue1000.com/bkhtml/c17/2013-03/71115.htm