Asp.Net MVC 2 CAPTCHA(güvenlik kodu) Uygulaması

Asp.Net 4 mvc 2 de CAPTCHA uygulamasının nasıl yapıldığını hep beraber görelim.
ilk önce yeni proje başlatalım.uygulamayı Visual C# web olarak seçiyoruz.

projemizin adı CAPTCHA olarak ayarlıyoruz.Aşağıdaki Resim gibi...

index.aspx deki ContentPlaceHolderID="MainContent" ın içine alttaki kodları ekliyoruz.

<h2><%= Html.Encode(ViewData["Message"]) %></h2>
    <% using (Html.BeginForm("index", "home")) { %>
    <p><img src="/home/getcaptcha" /></p>
    <p>Lütfen Kodu Yazınız::</p>
    <p><%=Html.TextBox("captcha")%></p>
    <p><input type="submit" value="Gönder" /></p>
    <% } %>
 

Daha sonra Controllers klasöründeki HomeController.cs e aşağıdaki kodları ekliyoruz.

using CAPTCHA.Models;
 [HttpPost]
        public ActionResult Index(string captcha)
        {
            if (captcha == HttpContext.Session["captcha"].ToString())
                ViewData["Message"] = "Kodlar doğru!";
            else
                ViewData["Message"] = "Kodlar yanlış.tekrar deneyin.!";

            return View();
        }

        public CaptchaResult GetCaptcha()
        {
            string captchaText = Captcha.GenerateRandomCode();
            HttpContext.Session.Add("captcha", captchaText);
            return new CaptchaResult(captchaText);
        }

Şimdi de Models klasörüne sağ tıklayıp add class diyoruz.Clasımızın adı ise Captcha.cs olacak.
Captcha.cs ın kodları ise şöyle;

using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;

namespace CAPTCHA.Models
{
    public class Captcha
    {
        private string text;
        private int width;
        private int height;
        private string familyName;
        private Bitmap image;
        private static Random random = new Random();

        public string FamilyName
        {
            get { return familyName; }
            set { familyName = value; }
        }
        public string Text
        {
            get { return this.text; }
            set { text = value; }
        }
        public Bitmap Image
        {
            get
            {
                if (!string.IsNullOrEmpty(text) && height > 0 && width > 0)
                    GenerateImage();
                return this.image;
            }
        }
        public int Width
        {
            get { return this.width; }
            set { width = value; }
        }
        public int Height
        {
            get { return this.height; }
            set { height = value; }
        }

        public Captcha()
        {

        }

        ~Captcha()
        {
            Dispose(false);
        }

        public void Dispose()
        {
            GC.SuppressFinalize(this);
            this.Dispose(true);
        }

        protected virtual void Dispose(bool disposing)
        {
            if (disposing)
                this.image.Dispose();
        }

        private void SetDimensions(int width, int height)
        {
            if (width <= 0)
                throw new ArgumentOutOfRangeException("width", width, "Argument out of range, must be greater than zero.");
            if (height <= 0)
                throw new ArgumentOutOfRangeException("height", height, "Argument out of range, must be greater than zero.");
            this.width = width;
            this.height = height;
        }

        private void SetFamilyName(string familyName)
        {
            try
            {
                Font font = new Font(this.familyName, 16F);
                this.familyName = familyName;
                font.Dispose();
            }
            catch
            {
                this.familyName = FontFamily.GenericSerif.Name;
            }
        }

        public void GenerateImage()
        {
         
            Bitmap bitmap = new Bitmap(this.width, this.height, PixelFormat.Format32bppArgb);
            Graphics g = Graphics.FromImage(bitmap);
            g.SmoothingMode = SmoothingMode.AntiAlias;
            Rectangle rect = new Rectangle(0, 0, this.width, this.height);
            HatchBrush hatchBrush = new HatchBrush(HatchStyle.SmallConfetti, Color.FromArgb(114, 172, 236), Color.FromArgb(161, 214, 255));
            g.FillRectangle(hatchBrush, rect);
            SizeF size;
            float fontSize = this.height + 4;
            Font font;
            do
            {
                fontSize--;
                font = new Font(this.familyName, fontSize, FontStyle.Bold);
                size = g.MeasureString(this.text, font);
            } while (size.Width > this.width);
            StringFormat format = new StringFormat();
            format.Alignment = StringAlignment.Center;
            format.LineAlignment = StringAlignment.Center;
            GraphicsPath path = new GraphicsPath();
            path.AddString(this.text, font.FontFamily, (int)font.Style, font.Size, rect, format);
            float v = 4F;
            PointF[] points =
                {
                    new PointF(random.Next(this.width) / v, random.Next(this.height) / v),
                    new PointF(this.width - random.Next(this.width) / v, random.Next(this.height) / v),
                    new PointF(random.Next(this.width) / v, this.height - random.Next(this.height) / v),
                    new PointF(this.width - random.Next(this.width) / v, this.height - random.Next(this.height) / v)
                };
            Matrix matrix = new Matrix();
            matrix.Translate(0F, 0F);
            path.Warp(points, rect, matrix, WarpMode.Perspective, 0F);
            hatchBrush = new HatchBrush(HatchStyle.SmallConfetti, ColorTranslator.FromHtml("#000000"), ColorTranslator.FromHtml("#000000"));
            g.FillPath(hatchBrush, path);
            int m = Math.Max(this.width, this.height);
            for (int i = 0; i < (int)(this.width * this.height / 30F); i++)
            {
                int x = random.Next(this.width);
                int y = random.Next(this.height);
                int w = random.Next(m / 50);
                int h = random.Next(m / 50);
                g.FillEllipse(hatchBrush, x, y, w, h);
            }
            font.Dispose();
            hatchBrush.Dispose();
            g.Dispose();
            this.image = bitmap;
        }

        public static string GenerateRandomCode()
        {
            string s = "";
            for (int i = 0; i < 6; i++)
                s = String.Concat(s, random.Next(10).ToString());
            return s;
        }
    }
}

Son olarak Models klasörüne CaptchaResult.cs adında bir class ekliyoruz.

using System.Drawing.Imaging;
using System.Web;
using System.Web.Mvc;
namespace CAPTCHA.Models
{
public class CaptchaResult : ActionResult
{
    public string _captchaText;
    public CaptchaResult(string captchaText)
    {
        _captchaText = captchaText;
    }
    public override void ExecuteResult(ControllerContext context)
    {
        Captcha c = new Captcha();
        c.Text = _captchaText;
        c.Width = 200;
        c.Height = 50;
        c.FamilyName = "Century Schoobook";
        HttpContextBase cb = context.HttpContext;
        cb.Response.Clear();
        cb.Response.ContentType = "image/jpeg";
        c.Image.Save(cb.Response.OutputStream, ImageFormat.Jpeg);
        c.Dispose();
    }
}
}

İşte bu kadar...