Image Verification Code Generation

Using System;
Using System. IO;
Using System. Web;
Using System. Text;
Using System. Drawing;
Using System. Drawing. Imaging;
/// <Summary>
/// Generate an image using Cls_PicVcode
/// </Summary>
Public class ValidateCode
{
/// <Summary>
/// This method is used to generate a random number of specified digits.
/// </Summary>
/// <Param name = "VcodeNum"> the parameter is the number of digits of a random number. </param>
/// <Returns> returns a random number string </returns>
Private string RndNum (int VcodeNum)
{
String Vchar = "1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F, G, H, I, J, K, L, M, n, P "+
", Q, R, S, T, U, V, W, X, Y, Z ";
String [] VcArray = Vchar. Split (new Char [] {,}); // Split it into an array
String VNum = ""; // random number generated
Int temp =-1; // record the previous random value. Avoid producing several identical random numbers.
Random rand = new Random ();
For (int I = 1; I <VcodeNum + 1; I ++)
{
If (temp! =-1)
{
Rand = new Random (I * temp * unchecked (int) DateTime. Now. Ticks ));
}
Int t = rand. Next (33 );
If (temp! =-1 & temp = t)
{
Return RndNum (VcodeNum );
}
Temp = t;
VNum + = VcArray [t];
}
Return VNum;
}
/// <Summary>
/// This method writes the generated random number to the image file
/// </Summary>
/// <Param name = "VNum"> VNum is a random number </param>
Public MemoryStream Create (out string VNum)
{
VNum = RndNum (4 );
Bitmap Img = null;
Graphics g = null;
MemoryStream MS = null;
System. Random random = new Random ();
// Set of verification code colors
Color [] c = {Color. Black, Color. Red, Color. DarkBlue, Color. Green, Color. Orange, Color. Brown, Color. DarkCyan, Color. Purple };
// Set of verification code Fonts
String [] fonts = {"Verdana", "Microsoft Sans Serif", "Comic Sans MS", "Arial", ""};

// Define the image size and generate an image instance
Img = new Bitmap (100, 25 );

G = Graphics. FromImage (Img); // generate a new Graphics object from the Img object

G. Clear (Color. White); // The background is White.

// Draw background points at random positions
For (int I = 0; I <100; I ++)
{
Int x = random. Next (Img. Width );
Int y = random. Next (Img. Height );
G. DrawRectangle (new Pen (Color. LightGray, 0), x, y, 1, 1 );
}
// The verification code is drawn in g
For (int I = 0; I <VNum. Length; I ++)
{
Int cindex = random. Next (7); // random color index value
Int findex = random. Next (5); // random font index value
Font f = new System. Drawing. Font (fonts [findex], 14, System. Drawing. FontStyle. Bold); // Font
Brush B = new System. Drawing. SolidBrush (c [cindex]); // color
Int ii = 4;
If (I + 1) % 2 = 0) // The control Verification Code is not in the same height
{
Ii = 2;
}
G. DrawString (VNum. Substring (I, 1), f, B, 3 + (I * 20), ii); // draw a verification character
}
MS = new MemoryStream (); // generates a memory stream object
Img. Save (MS, ImageFormat. Jpeg); // Save this image as a jpg image file to the stream

// Reclaim Resources
G. Dispose ();
Img. Dispose ();
Return MS;

}
}