protected void Page_Load(object sender, EventArgs e)
{
CreateCheckCodeImage(GenerateCheckCode());
}
private string GenerateCheckCode()
{
int num;
char code;
string checkcode = string.Empty;
Random rand = new Random();
for (int i = 0; i < 4; i++)
{
num = rand.Next();
if(num%2==0)
code=(char)('0'+(char)(num%10));
else
code=(char)('A'+(char)(num%26));
checkcode+=code.ToString();
}
Response.Cookies.Add(new HttpCookie("checkcode",checkcode));
return checkcode;
}
private void CreateCheckCodeImage(string checkCode)
{
if (checkCode == null || checkCode.Trim() == string.Empty)
return;
System.Drawing.Bitmap image = new Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), 22);
Graphics g = Graphics.FromImage(image);
try
{
Random rand = new Random();
g.Clear(Color.White);
for (int i = 0; i < 2; i++)
{
int x1 = rand.Next(image.Width);
int x2 = rand.Next(image.Width);
int y1 = rand.Next(image.Height);
int y2 = rand.Next(image.Height);
g.DrawLine(new Pen(Color.Black), x1, y1, x2, y2);
}
Font font = new Font("Arial", 12, (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);
for (int i = 0; i < 100; i++)
{
int x = rand.Next(image.Width);
int y = rand.Next(image.Height);
image.SetPixel(x, y, Color.FromArgb(rand.Next()));
}
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();
}
}
}