C# 生成验证码图片时消除锯齿

工程师昊然技术 2022年11月13日

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引言

基于生成图片实现了一个手机号转图片的需求。内容也很简单，直接用手机号生成一个png图片。就是为了背景透明以便其他地方调用。有无锯齿主要依靠一句代码：g.TextRenderingHint= TextRenderingHint.AntiAlias;

生成图片

1、有锯齿

2、无锯齿

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; //消除锯齿            //生成随机生成器
            Random random = new Random();            //清空图片背景色
            //g.Clear(Color.Transparent);            //画图片的背景噪音线
            /*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);            //画图片的前景噪音点
            //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()));
            //}            //画图片的边框线
            //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();
        }