1using System;
2using System.Drawing;
3using System.Drawing.Drawing2D;
4using System.Drawing.Imaging;
5using System.Drawing.Text;
6
7namespace Captcha
8{
9	public class CaptchaImage
10	{
11		#region Public Properties   ...
12
13		public Bitmap Bitmap
14		{
15			get { return mobjBitmap; }
16		}
17		#endregion
18		#region Private vars   ...
19
20		private string mstrText;
21		private int mintWidth = 200;
22		private int mintHeight = 50;
23		private string mstrFont = System.Drawing.FontFamily.GenericSerif.Name;
24		private Bitmap mobjBitmap;
25		private Random mobjRandom = new Random();
26		#endregion
27		#region Constr/Deconstr   ...
28
29		public CaptchaImage(string strText, int intWidth, int intHeight)
30		{
31			mstrText = strText;
32			mintWidth = intWidth;
33			mintHeight = intHeight;
34			CreateCaptcha();
35		}
36
37		public CaptchaImage(string strText, string strFont, int intWidth, int intHeight)
38		{
39			mstrText = strText;
40			mintWidth = intWidth;
41			mintHeight = intHeight;
42			Font objFont = null;
43			try
44			{
45				objFont = new Font(strFont, 12F);
46				mstrFont = strFont;
47				objFont.Dispose();
48			}
49			catch
50			{}
51			finally
52			{
53				objFont = null;
54			}
55			CreateCaptcha();
56		}
57		~CaptchaImage()
58		{
59			Dispose(false);
60		}
61		public void Dispose()
62		{
63			GC.SuppressFinalize(this);
64			Dispose(true);
65		}
66		protected virtual void Dispose(bool disposing)
67		{
68			if (disposing)
69				mobjBitmap.Dispose();
70		}
71		#endregion
72		#region CreateCaptcha   ...
73
74		private void CreateCaptcha()
75		{
76			//Create instance of bitmap object
77			Bitmap objBitmap = new Bitmap(mintWidth, mintHeight, PixelFormat.Format32bppArgb);
78			
79			//Create instance of graphics object
80			Graphics objGraphics = Graphics.FromImage(objBitmap);
81			objGraphics.SmoothingMode = SmoothingMode.AntiAlias;
82			Rectangle objRect = new Rectangle(0, 0, mintWidth, mintHeight);
83
84			//Fill the background in a light gray pattern
85			HatchBrush objHatchBrush = new HatchBrush(HatchStyle.DiagonalCross, Color.LightGray, Color.White);
86			objGraphics.FillRectangle(objHatchBrush, objRect);
87
88			//Determine the appropriate font size
89			SizeF objSize;
90			float flFontSize = objRect.Height + 1;
91			Font objFont;
92			do	//Decrease font size until text fits within the space
93			{
94				flFontSize--;
95				objFont = new Font(mstrFont, flFontSize, FontStyle.Bold);
96				objSize = objGraphics.MeasureString(mstrText, objFont);
97			} while (objSize.Width > objRect.Width);
98
99			//Format the text
100			StringFormat objStringFormat = new StringFormat();
101			objStringFormat.Alignment = StringAlignment.Center;
102			objStringFormat.LineAlignment = StringAlignment.Center;
103
104			//Create a path using the text and randomly warp it
105			GraphicsPath objGraphicsPath = new GraphicsPath();
106			objGraphicsPath.AddString(mstrText, objFont.FontFamily, (int)objFont.Style, objFont.Size, objRect, objStringFormat);
107			float flV = 4F;
108
109			//Create a parallelogram for the text to draw into
110			PointF[] arrPoints =
111			{
112				new PointF(mobjRandom.Next(objRect.Width) / flV, mobjRandom.Next(objRect.Height) / flV),
113				new PointF(objRect.Width - mobjRandom.Next(objRect.Width) / flV, mobjRandom.Next(objRect.Height) / flV),
114				new PointF(mobjRandom.Next(objRect.Width) / flV, objRect.Height - mobjRandom.Next(objRect.Height) / flV),
115				new PointF(objRect.Width - mobjRandom.Next(objRect.Width) / flV, objRect.Height - mobjRandom.Next(objRect.Height) / flV)
116			};
117
118			//Create the warped parallelogram for the text
119			Matrix objMatrix = new Matrix();
120			objMatrix.Translate(0F, 0F);
121			objGraphicsPath.Warp(arrPoints, objRect, objMatrix, WarpMode.Perspective, 0F);
122
123			//Add the text to the shape
124			objHatchBrush = new HatchBrush(HatchStyle.LargeConfetti, Color.DarkGray, Color.Black);
125			objGraphics.FillPath(objHatchBrush, objGraphicsPath);
126
127			//Add some random noise
128			int intMax = Math.Max(objRect.Width, objRect.Height);
129			for (int i = 0; i < (int) (objRect.Width * objRect.Height / 30F); i++)
130			{
131				int x = mobjRandom.Next(objRect.Width);
132				int y = mobjRandom.Next(objRect.Height);
133				int w = mobjRandom.Next(intMax / 15);
134				int h = mobjRandom.Next(intMax / 70);
135				objGraphics.FillEllipse(objHatchBrush, x, y, w, h);
136			}
137
138			//Release memory
139			objFont.Dispose();
140			objHatchBrush.Dispose();
141			objGraphics.Dispose();
142
143			//Set the public property to the 
144			mobjBitmap = objBitmap;
145		}
146		#endregion
147	}
148}