使用跨平台库SixLabors.ImageSharp.Drawing生成图片验证码

 /// <summary>
 /// 绘制图片验证码
 /// </summary>
 /// <param name="webRootPath"></param>
 /// <param name="width"></param>
 /// <param name="height"></param>
 /// <returns></returns>
 public static string GenerateImgVerifyCode(string verifyCode, int width = 120, int height = 50)
 {
     ////根据验证码的长度确定输出图片的宽度
     //int iWidth = (int)Math.Ceiling(verifyCode.Code.Length * 15m);

     using Image image = new Image<Rgba32>(width, height);
     //漆底色白色
     image.Mutate(x => x.DrawLine(Pens.DashDot(Color.White, width), new PointF[] { new PointF() { X = 0, Y = 0 }, new PointF() { X = width, Y = height } }));

     FontCollection collection = new();
     //加载字体
     FontFamily family = collection.Add("./wwwroot/FZHTJW.TTF");
     Font font = family.CreateFont(20, FontStyle.Bold);

     PointF startPointF = new PointF(5, 5);
     Random random = new Random(); //随机数产生器

     Color[] colors = new Color[] { Color.Red, Color.Blue, Color.Green, Color.Purple, Color.Peru, Color.LightSeaGreen, Color.Lime, Color.Magenta, Color.Maroon, Color.MediumBlue, Color.MidnightBlue, Color.Navy };
     //绘制验证码
     for (int i = 0; i < verifyCode.Length; i++)
     {
         image.Mutate(x => x.DrawText(verifyCode[i].ToString(), font, colors[random.Next(colors.Length)], startPointF));
         startPointF.X += (int)(width - 10) / verifyCode.Length;
         startPointF.Y = random.Next(5, 10);
     }

     var pen = Pens.DashDot(Color.Silver, 1);

     //绘制银色背景噪音线30条
     for (var k = 0; k < 30; k++)
     {
         PointF[] points = new PointF[2];
         points[0] = new PointF(random.Next(width), random.Next(height));
         points[1] = new PointF(random.Next(width), random.Next(height));
         image.Mutate(x => x.DrawLine(pen, points));
     }
     using (MemoryStream stream = new MemoryStream())
     {

         image.Save(stream, PngFormat.Instance);
         byte[] arr = new byte[stream.Length];
         stream.Position = 0;
         stream.Read(arr, 0, (int)stream.Length);
         stream.Close();
         return Convert.ToBase64String(arr);
     };

 }

注意：准备字体库 “FZHTJW.TTF”