[转]C#动态生成文字图片

本文转自：http://hi.baidu.com/lantis214/blog/item/e53c35fe83a950355d60083f.html

原文如下

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using System;

using System.Data;

using System.Configuration;

using System.Collections;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Web.UI.HtmlControls;

using System.Drawing;

using System.Drawing.Imaging;

using System.Drawing.Drawing2D;

using System.Collections.Generic;

using System.Text;

public partial class Default2 : System.Web.UI.Page

{

protected void Page_Load(object sender, EventArgs e)

{

this.CreateCheckCodeImage(GenerateCheckCode());

}

private string GenerateCheckCode()

{

//int number;

//char code;

string checkCode = String.Empty;

System.Random random = new Random();

Encoding gb = Encoding.GetEncoding("gb2312");

//调用函数产生4个随机中文汉字编码

object[] bytes = CreateRegionCode(6);

//根据汉字编码的字节数组解码出中文汉字

string str1 = gb.GetString((byte[])Convert.ChangeType(bytes[0], typeof(byte[])));

string str2 = gb.GetString((byte[])Convert.ChangeType(bytes[1], typeof(byte[])));

string str3 = gb.GetString((byte[])Convert.ChangeType(bytes[2], typeof(byte[])));

string str4 = gb.GetString((byte[])Convert.ChangeType(bytes[3], typeof(byte[])));

//输出的控制台

checkCode = str1 + str2 + str3 + str4;

Response.Cookies.Add(new HttpCookie("ValidCode", checkCode));

return checkCode;

}

#region 产生波形滤镜效果

private static object[] CreateRegionCode(int strlength)

{

//定义一个字符串数组储存汉字编码的组成元素

string[] rBase = new String[16] { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };

Random rnd = new Random();

//定义一个object数组用来

object[] bytes = new object[strlength];

/*每循环一次产生一个含两个元素的十六进制字节数组，并将其放入bject数组中

每个汉字有四个区位码组成

区位码第1位和区位码第2位作为字节数组第一个元素

区位码第3位和区位码第4位作为字节数组第二个元素

*/

for (int i = 0; i < strlength; i++)

{

//区位码第1位

int r1 = rnd.Next(11, 14);

string str_r1 = rBase[r1].Trim();

//区位码第2位

rnd = new Random(r1 * unchecked((int)DateTime.Now.Ticks) + i);//更换随机数发生器的

//种子避免产生重复值

int r2;

if (r1 == 13)

{

r2 = rnd.Next(0, 7);

}

else

{

r2 = rnd.Next(0, 16);

}

string str_r2 = rBase[r2].Trim();

//区位码第3位

rnd = new Random(r2 * unchecked((int)DateTime.Now.Ticks) + i);

int r3 = rnd.Next(10, 16);

string str_r3 = rBase[r3].Trim();

//区位码第4位

rnd = new Random(r3 * unchecked((int)DateTime.Now.Ticks) + i);

int r4;

if (r3 == 10)

{

r4 = rnd.Next(1, 16);

}

else if (r3 == 15)

{

r4 = rnd.Next(0, 15);

}

else

{

r4 = rnd.Next(0, 16);

}

string str_r4 = rBase[r4].Trim();

//定义两个字节变量存储产生的随机汉字区位码

byte byte1 = Convert.ToByte(str_r1 + str_r2, 16);

byte byte2 = Convert.ToByte(str_r3 + str_r4, 16);

//将两个字节变量存储在字节数组中

byte[] str_r = new byte[] { byte1, byte2 };

//将产生的一个汉字的字节数组放入object数组中

bytes.SetValue(str_r, i);

}

return bytes;

}

private const double PI = 3.1415926535897932384626433832795;

private const double PI2 = 6.283185307179586476925286766559;

private System.Drawing.Bitmap TwistImage(Bitmap srcBmp, bool bXDir, double dMultValue, double dPhase)

{

System.Drawing.Bitmap destBmp = new Bitmap(srcBmp.Width, srcBmp.Height);

// 将位图背景填充为白色

System.Drawing.Graphics graph = System.Drawing.Graphics.FromImage(destBmp);

graph.FillRectangle(new SolidBrush(System.Drawing.Color.White), 0, 0, destBmp.Width, destBmp.Height);

graph.Dispose();

double dBaseAxisLen = bXDir ? (double)destBmp.Height : (double)destBmp.Width;

for (int i = 0; i < destBmp.Width; i++)

{

for (int j = 0; j < destBmp.Height; j++)

{

double dx = 0;

dx = bXDir ? (PI2 * (double)j) / dBaseAxisLen : (PI2 * (double)i) / dBaseAxisLen;

dx += dPhase;

double dy = Math.Sin(dx);

// 取得当前点的颜色

int nOldX = 0, nOldY = 0;

nOldX = bXDir ? i + (int)(dy * dMultValue) : i;

nOldY = bXDir ? j : j + (int)(dy * dMultValue);

System.Drawing.Color color = srcBmp.GetPixel(i, j);

if (nOldX >= 0 && nOldX < destBmp.Width

&& nOldY >= 0 && nOldY < destBmp.Height)

{

destBmp.SetPixel(nOldX, nOldY, color);

}

}

}

return destBmp;

}

#endregion

private void CreateCheckCodeImage(string checkCode)

{

if (checkCode == null)

return;

System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 27.0)), 25);

Graphics g = Graphics.FromImage(image);

try

{

//生成随机生成器

Random random = new Random();

//清空图片背景色

g.Clear(Color.White);

//画图片的背景噪音线

for (int i = 0; i < 12; i++)

{

int x1 = random.Next(image.Width);

int x2 = random.Next(image.Width);

int y1 = random.Next(image.Height);

int y2 = random.Next(image.Height);

g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);

}

//Font font = new System.Drawing.Font("Arial", 16, (System.Drawing.FontStyle.Bold 　 System.Drawing.FontStyle.Italic));

Font font = new System.Drawing.Font("楷体_GB2312", 16, (System.Drawing.FontStyle.Bold));

System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);

g.DrawString(checkCode, font, brush, 2, 2);

//画图片的前景噪音点

for (int i = 0; i < 100; i++)

{

int x = random.Next(image.Width);

int y = random.Next(image.Height);

image.SetPixel(x, y, Color.FromArgb(random.Next()));

}

//image = TwistImage(image, true, 3, 1);

//画图片的波形滤镜效果

//画图片的边框线

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

System.IO.MemoryStream ms = new System.IO.MemoryStream();

image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);

Response.ClearContent();

Response.ContentType = "image/Gif";

Response.BinaryWrite(ms.ToArray());

}

finally

{

g.Dispose();

image.Dispose();

}

}

}