Bitmap cannot add custom background-CodePudding

I am using the project of asp.net core3.1 now. I downloaded Bitmap using command.

public class VierificationCodeServices
      {
        
          private string RndNum(int VcodeNum)
          {
             
            string Vchar = "0,1,2,3,4,5,6,7,8,9,a,b,c,d,e,f,g,h,i,j,k,l,m,n,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,P,P,Q"  
                 ",R,S,T,U,V,W,X,Y,Z";
             string[] VcArray = Vchar.Split(new Char[] { ',' });  
             string code = "";
             int temp = -1;
 
             Random rand = new Random();
           
             for (int i = 1; i < VcodeNum   1; i  )
             {
                if (temp != -1)
                {
                     rand = new Random(i * temp * unchecked((int)DateTime.Now.Ticks)); 
                }
                int t = rand.Next(61);
                 if (temp != -1 && temp == t)
                {
                     return RndNum(VcodeNum);
                 }
                 temp = t;
                 code  = VcArray[t]; 
             }
             return code;
         }

I'm done with random numbers, how do I insert that background image and font style into it?

CodePudding user response：

You can use this ready-made code：

controller:

 [Route("get_captcha")]
        [HttpGet]
        public Object VerifyCode()
        {
            string code = "";
            Bitmap bitmap = Captcha.CreateCaptcha(out code);
            MemoryStream stream = new MemoryStream();
            bitmap.Save(stream, ImageFormat.Gif);
            return File(stream.ToArray(), "image/gif");
        }

Generate verification code and add background style:

 public class Captcha
    {
        public  static Bitmap CreateCaptcha(out string code)
        {
            //Create a Bitmap object and draw
            Bitmap bitmap = new Bitmap(200, 60);
            Graphics graph = Graphics.FromImage(bitmap);
            graph.FillRectangle(new SolidBrush(Color.White), 0, 0, 200, 60);
            Font font = new Font(FontFamily.GenericSerif, 48, FontStyle.Bold, GraphicsUnit.Pixel);
            Random r = new Random();
            string letters = "0123456789abcdefghijklmnpqrstuvwxyzABCDEFGHIJKLMNPPQRSTUVWXYZ";
           // string[] VcArray = letters.Split(new Char[] { ',' });
            StringBuilder sb = new StringBuilder();

            //Add random 4 numbers
            for (int x = 0; x < 4; x  )
            {
                string letter = letters.Substring(r.Next(0, letters.Length - 1), 1);
                sb.Append(letters);
                graph.DrawString(letter, font, new SolidBrush(Color.Black), x * 38, r.Next(0, 15));
            }
            code = sb.ToString();

            //Confuse the background
            Pen linePen = new Pen(new SolidBrush(Color.Black), 2);
            for (int x = 0; x < 6; x  )
                graph.DrawLine(linePen, new Point(r.Next(0, 199), r.Next(0, 59)), new Point(r.Next(0, 199), r.Next(0, 59)));
            return bitmap;
        }
    }