verifyimage.cs

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/*
 * Discuz!NT Version: 1.0
 * Created on 2007-3-30
 *
 * Web: http://www.discuznt.com
 * Copyright (C) 2001 - 2007 Comsenz Technology Inc., All Rights Reserved.
 * This is NOT a freeware, use is subject to license terms.
 *
 */


using System;
using System.IO;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.Drawing.Text;
using System.Security.Cryptography;

namespace Discuz.Forum
{

	/// <summary>
	/// 验证码图片类
	/// </summary>
	public class VerifyImage
	{
		/// <summary>
		/// 要显示的文字
		/// </summary>
		public string Text
		{
			get { return this.text; }
		}
		/// <summary>
		/// 图片
		/// </summary>
		public Bitmap Image
		{
			get { return this.image; }
		}
		/// <summary>
		/// 宽度
		/// </summary>
		public int Width
		{
			get { return this.width; }
		}
		/// <summary>
		/// 高度
		/// </summary>
		public int Height
		{
			get { return this.height; }
		}

		private string text;
		private int width;
		private int height;
		private Bitmap image;

		private static byte[] randb = new byte[4];
		private static RNGCryptoServiceProvider rand = new RNGCryptoServiceProvider();

		/// <summary>
		/// 构造函数
		/// </summary>
		/// <param name="code">要显示的验证码</param>
		/// <param name="width">宽度</param>
		/// <param name="height">高度</param>
		public VerifyImage(string code, int width, int height)
		{
			this.text = code;
			this.width = width;
			this.height = height;
			this.GenerateImage();

		}

		~VerifyImage()
		{
			Dispose(false);
		}

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

		protected virtual void Dispose(bool disposing)
		{
			if (disposing)
				this.image.Dispose();
		}
		private FontFamily[] fonts = {
										 new FontFamily("Times New Roman"),
										 new FontFamily("Georgia"),
										 new FontFamily("Arial"),
										 new FontFamily("Comic Sans MS")
									 };
		
		/// <summary>
		/// 获得下一个随机数
		/// </summary>
		/// <returns></returns>
		public static int Next()
		{
			rand.GetBytes(randb);
			int value = BitConverter.ToInt32(randb, 0);
			if (value < 0) value = -value;
			return value;
		}

		/// <summary>
		/// 获得下一个随机数
		/// </summary>
		/// <param name="max">最大值</param>
		/// <returns></returns>
		public static int Next(int max)
		{
			rand.GetBytes(randb);
			int value = BitConverter.ToInt32(randb, 0);
			value = value % (max + 1);
			if (value < 0) value = -value;
			return value;
		}

		/// <summary>
		/// 获得下一个随机数
		/// </summary>
		/// <param name="min">最小值</param>
		/// <param name="max">最大值</param>
		/// <returns></returns>
		public static int Next(int min, int max)
		{
			int value = Next(max - min) + min;
			return value;
		}		
	
		
		/// <summary>
		/// 生成验证码图片
		/// </summary>
		private void GenerateImage()
		{
			Bitmap bitmap = new Bitmap(this.width, this.height, PixelFormat.Format32bppArgb);

			Graphics g = Graphics.FromImage(bitmap);
			Rectangle rect = new Rectangle(0, 0, this.width, this.height);
			g.SmoothingMode = SmoothingMode.AntiAlias;

			g.Clear(Color.White);
			
			int emSize = Next(3) + 15;//(int)((this.width - 20) * 2 / text.Length);
			FontFamily family = fonts[Next(fonts.Length - 1)];
			Font font = new Font(family, emSize, FontStyle.Bold);

			SizeF measured = new SizeF(0, 0);
			SizeF workingSize = new SizeF(this.width, this.height);
			while (emSize > 2 && (measured = g.MeasureString(text, font)).Width > workingSize.Width || measured.Height > workingSize.Height)
			{
				font.Dispose();
				font = new Font(family, emSize -= 2);
			}

			SolidBrush drawBrush = new SolidBrush(Color.FromArgb(Next(100), Next(100), Next(100)));
			for (int x = 0; x < 3; x++)
			{
				Pen linePen = new Pen(Color.FromArgb(Next(150), Next(150), Next(150)), 1);
				g.DrawLine(linePen, new PointF(0.0F+Next(20), 0.0F+Next(this.height)), new PointF(0.0F+Next(this.width), 0.0F+Next(this.height)));
			}
			
			for (int x = 0; x < this.text.Length; x++)
			{
				drawBrush.Color = Color.FromArgb(Next(150) + 20, Next(150) + 20, Next(150) + 20);
				PointF drawPoint = new PointF(0.0F+Next(4) + x * 15, 8.0F+Next(4));
				g.DrawString(this.text[x].ToString(), font, drawBrush, drawPoint);
			}

			double distort = Next(5, 10) * (Next(10) == 1 ? 1 : -1);

			using (Bitmap copy = (Bitmap)bitmap.Clone())
			{
				for (int y = 0; y < height; y++)
				{
					for (int x = 0; x < width; x++)
					{
						int newX = (int)(x + (distort * Math.Sin(Math.PI * y / 84.0)));
						int newY = (int)(y + (distort * Math.Cos(Math.PI * x / 54.0)));
						if (newX < 0 || newX >= width) newX = 0;
						if (newY < 0 || newY >= height) newY = 0;
						bitmap.SetPixel(x, y, copy.GetPixel(newX, newY));
					}
				}
			}


			//g.DrawRectangle(new Pen(Color.Silver), 0, 0, bitmap.Width - 1, bitmap.Height - 1);

			font.Dispose();
			drawBrush.Dispose();
			g.Dispose();

			this.image = bitmap;
		}

	}
}