using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.Drawing.Text;
namespace CaptchaImage
{
  /// <summary>
  /// Summary description for CaptchaImage.
  /// </summary>
  public class CaptchaImage
  {
    // Public properties (all read-only).
    public string Text
    {
      get
      {
        return this.text;
      }
    }
    public Bitmap Image
    {
      get
      {
        return this.image;
      }
    }
    public int Width
    {
      get
      {
        return this.width;
      }
    }
    public int Height
    {
      get
      {
        return this.height;
      }
    }
    // Internal properties.
    private string text;
    private int width;
    private int height;
    private string familyName;
    private Bitmap image;
    // For generating random numbers.
    private Random random = new Random();
    // ====================================================================
    // Initializes a new instance of the CaptchaImage class using the
    // specified text, width and height.
    // ====================================================================
    public CaptchaImage(string s, int width, int height)
    {
      this.text = s;
      this.SetDimensions(width, height);
      this.GenerateImage();
    }
    // ====================================================================
    // Initializes a new instance of the CaptchaImage class using the
    // specified text, width, height and font family.
    // ====================================================================
    public CaptchaImage(string s, int width, int height, string familyName)
    {
      this.text = s;
      this.SetDimensions(width, height);
      this.SetFamilyName(familyName);
      this.GenerateImage();
    }
    // ====================================================================
    // This member overrides Object.Finalize.
    // ====================================================================
    ~CaptchaImage()
    {
      Dispose(false);
    }
    // ====================================================================
    // Releases all resources used by this object.
    // ====================================================================
    public void Dispose()
    {
      GC.SuppressFinalize(this);
      this.Dispose(true);
    }
    // ====================================================================
    // Custom Dispose method to clean up unmanaged resources.
    // ====================================================================
    protected virtual void Dispose(bool disposing)
    {
      if (disposing)
      // Dispose of the bitmap.
        this.image.Dispose();
    }
    // ====================================================================
    // Sets the image width and height.
    // ====================================================================
    private void SetDimensions(int width, int height)
    {
      // Check the width and 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;
    }
    // ====================================================================
    // Sets the font used for the image text.
    // ====================================================================
    private void SetFamilyName(string familyName)
    {
      // If the named font is not installed, default to a system font.
      try
      {
        Font font = new Font(this.familyName, 12F);
        this.familyName = familyName;
        font.Dispose();
      }
      catch (Exception ex)
      {
        this.familyName = System.Drawing.FontFamily.GenericSerif.Name;
      }
    }
    // ====================================================================
    // Creates the bitmap image.
    // ====================================================================
    private void GenerateImage()
    {
      // Create a new 32-bit bitmap image.
      Bitmap bitmap = new Bitmap(this.width, this.height, PixelFormat.Format32bppArgb);
      // Create a graphics object for drawing.
      Graphics g = Graphics.FromImage(bitmap);
      g.SmoothingMode = SmoothingMode.AntiAlias;
      Rectangle rect = new Rectangle(0, 0, this.width, this.height);
      // Fill in the background.
      HatchBrush hatchBrush = new HatchBrush(HatchStyle.SmallConfetti, Color.LightGray, Color.White);
      g.FillRectangle(hatchBrush, rect);
      // Set up the text font.
      SizeF size;
      float fontSize = rect.Height + 1;
      Font font;
      // Adjust the font size until the text fits within the image.
      do
      {
        fontSize--;
        font = new Font(this.familyName, fontSize, FontStyle.Bold);
        size = g.MeasureString(this.text, font);
      }while (size.Width > rect.Width);
      // Set up the text format.
      StringFormat format = new StringFormat();
      format.Alignment = StringAlignment.Center;
      format.LineAlignment = StringAlignment.Center;
      // Create a path using the text and warp it randomly.
      GraphicsPath path = new GraphicsPath();
      path.AddString(this.text, font.FontFamily, (int)font.Style, font.Size, rect, format);
      float v = 4F;
      PointF[] points =  { new PointF(this.random.Next(rect.Width) / v, this.random.Next(rect.Height) / v), new PointF(rect.Width - this.random.Next(rect.Width) / v, this.random.Next(rect.Height) / v), new PointF(this.random.Next(rect.Width) / v, rect.Height - this.random.Next(rect.Height) / v), new PointF(rect.Width - this.random.Next(rect.Width) / v, rect.Height - this.random.Next(rect.Height) / v) };
      Matrix matrix = new Matrix();
      matrix.Translate(0F, 0F);
      path.Warp(points, rect, matrix, WarpMode.Perspective, 0F);
      // Draw the text.
      hatchBrush = new HatchBrush(HatchStyle.LargeConfetti, Color.LightGray, Color.DarkGray);
      g.FillPath(hatchBrush, path);
      // Add some random noise.
      int m = Math.Max(rect.Width, rect.Height);
      for (int i = 0; i < (int)(rect.Width * rect.Height / 30F); i++)
      {
        int x = this.random.Next(rect.Width);
        int y = this.random.Next(rect.Height);
        int w = this.random.Next(m / 50);
        int h = this.random.Next(m / 50);
        g.FillEllipse(hatchBrush, x, y, w, h);
      }
      // Clean up.
      font.Dispose();
      hatchBrush.Dispose();
      g.Dispose();
      // Set the image.
      this.image = bitmap;
    }
  }
}