C # Generate good-looking verification code

Website Login always will use the verification code, generate verification code for C # is very simple, I use a general handler to write the verification code. The specific code is as follows:

Using System;
Using System.Collections.Generic;
Using System.Drawing;
Using System.Linq;
Using System.Web;

Namespace Ui.ajax
{
//<summary>
///Code Summary
//</summary>
public class Code:ihtt Phandler
{
//<summary>
//Authentication code type (0-alphanumeric mix, 1-digit, 2-letter)
//</summary>
private string Validatecodetype = "0";
public void ProcessRequest (HttpContext context)
{
context. Response.ContentType = "Text/plain";
Context. Response.bufferoutput = true;
Context. Response.Cache.SetExpires (DateTime.Now.AddMilliseconds (-1));
Context. Response.Cache.SetCacheability (Httpcacheability.nocache);
Context. Response.appendheader ("Pragma", "No-cache");
String validatecode = Generatecheckcode ();
//context. session["Checkcode"] = validatecode;//Saves the string to the session so that it can be validated when needed
Createcheckcodeimage (context, Validatecode);
}
public void Createcheckcodeimage (HttpContext context, string Checkcode)
{

int randangle = 40; Random Rotation angle
int mapwidth = (int) (CHECKCODE.LENGTH * 18);
Bitmap map = new Bitmap (mapwidth, 24);//Create picture background
Graphics graph = graphics.fromimage (map);
Graph. Clear (Color.White);//erase screen, fill background
Graph. DrawRectangle (New Pen (Color.lightgray, 0), 0, 0, map. Width-1, map. HEIGHT-1);//Draw a border

Random rand = new Random ();

Verification code rotation to prevent machine identification
char[] chars = Checkcode.tochararray ();//break string into a single character array
In text distance
StringFormat format = new StringFormat (stringformatflags.noclip);
Format. Alignment = Stringalignment.center;
Format. LineAlignment = Stringalignment.center;
Define Color
Color[] C = {color.black, color.red, Color.Blue, Color.green, Color.orange, Color.brown, color.darkblue};

Draw a picture of the background noise line
for (int i = 0; i < 2; i++)
{
int x1 = Rand. Next (10);
int x2 = rand. Next (map. WIDTH-10, map. Width);
int y1 = rand. Next (map. Height);
int y2 = rand. Next (map. Height);

Graph. DrawLine (New Pen (C[rand. Next (7)]), x1, y1, x2, y2);
}

for (int i = 0; i < chars. Length; i++)
{
int cindex = rand. Next (7);
int findex = rand. Next (5);
Font f = new System.Drawing.Font ("Arial", System.Drawing.FontStyle.Regular);//font style (parameter 2 is font size)
Brush B = new System.Drawing.SolidBrush (C[cindex]);
Point dot = new Point (12, 16);
float angle = rand. Next (-randangle, randangle);//degrees of rotation
Graph. TranslateTransform (dot. X, Dot. Y);//move cursor to specified position
Graph. RotateTransform (angle);
Graph. DrawString (Chars[i]. ToString (), F, B, 1, 1, format);
Graph. RotateTransform (-angle);//Turn Back
Graph. TranslateTransform (2,-dot. Y);//move cursor to specified position
}
Create a picture
System.IO.MemoryStream ms = new System.IO.MemoryStream ();
Map. Save (MS, SYSTEM.DRAWING.IMAGING.IMAGEFORMAT.GIF);
Context. Response.clearcontent ();
Context. Response.ContentType = "Image/gif";
Context. Response.BinaryWrite (Ms. ToArray ());
Graph. Dispose ();
Map. Dispose ();
}
private String Generatecheckcode ()
{
int number;
char code;
string checkcode = String.Empty;
System.Random random = new Random ();
for (int i = 0; i < 4; i++)
{
Number = random. Next ();
Code = (char) (' 0 ' + (char) (number% 10));
if (number% 2 = = 0)
Code = (char) (' 0 ' + (char) (number% 10));
Else
Code = (char) (' A ' + (char) (number% 26));
Remove 0,o,i,o,i,z,z
if (code. ToString () = = "O" | | Code. ToString () = = "I" | | Code. ToString () = = "O" | | Code. ToString () = = "I" | | Code. ToString () = = "Z" | | Code. ToString () = = "Z")
{
i--;
Continue
}
All numbers are required.
if (Validatecodetype = = "1")
{
if ((int) code < 48 | | (int) code > 57)
{
i--;
Continue
}
}
All letters are required.
if (Validatecodetype = = "2")
{
if ((int) code > 47 | | (int) Code < 58)
{
i--;
Continue
}
}
Checkcode + = code. ToString ();
}
return checkcode;
}

public bool IsReusable
{
Get
{
return false;
}
}
}
}

The specific effect is:

C # Generate good-looking verification code