Phpci framework verification code instance Analysis _ PHP-php Tutorial

This article provides a detailed analysis of the ci framework verification code examples. For more information, see the CI framework.

Php code:
The code is as follows:
Class Captcha_code
{
Var $ width = '60 ';
Var $ num = '4 ';
Var $ height = '20 ';
Var $ name = 'randcode ';
Public function _ construct ($ conf = "")
{
If ($ conf! = "")
{
Foreach ($ conf as $ key => $ value)
{
$ This-> $ key = $ value;
}
}
}

Function show ()
{
Header ("Content-type: image/gif ");
/*
* Initialization
*/
$ Border = 0; // whether the border is required; 1: 0: not required
$ How = $ this-> num; // Number of digits of the verification code
$ W = $ this-> width; // image width
$ H = $ this-> height; // Image height
$ Fontsize = 5; // font size
$ Alpha = "abcdefghijkmnopqrstuvwxyz"; // verification code content 1: letter
$ Number = "023456789"; // verification code content 2: number
$ Randcode = ""; // verification code string initialization
Srand (double) microtime () * 1000000); // initialize the random number seed

$ Im = ImageCreate ($ w, $ h); // Create a verification image

/*
* Draw the basic framework
*/
$ Bgcolor = ImageColorAllocate ($ im, 255,255,255); // you can specify the background color.
ImageFill ($ im, 0, 0, $ bgcolor); // fill the background color
If ($ border)
{
$ Black = ImageColorAllocate ($ im, 0, 0, 0); // you can specify the border color.
ImageRectangle ($ im, 0, 0, $ W-1, $ H-1, $ black); // draw a border
}

/*
* Generate random characters by bit
*/
For ($ I = 0; $ I <$ how; $ I ++)
{
$ Alpha_or_number = mt_rand (0, 1); // letters or numbers
$ Str = $ alpha_or_number? $ Alpha: $ number;
$ Which = mt_rand (0, strlen ($ str)-1); // specify the character
$ Code = substr ($ str, $ which, 1); // Obtain the character
$ J =! $ I? 4: $ j + 15; // specifies the position of the painted character.
$ Color3 = ImageColorAllocate ($ im, mt_rand (0,100), mt_rand (0,100), mt_rand (0,100); // character color
ImageChar ($ im, $ fontsize, $ j, 3, $ code, $ color3); // draw characters
$ Randcode. = $ code; // add a verification code string to a bit by bit
}

/*
* Add interference
*/
For ($ I = 0; $ I <5; $ I ++) // draws the background interference line
{
$ Color1 = ImageColorAllocate ($ im, mt_rand (0,255), mt_rand (0,255), mt_rand (0,255); // interference line color
ImageArc ($ im, mt_rand (-5, $ w), mt_rand (-5, $ h), mt_rand (20,300), mt_rand (20,200), 55, 44, $ color1); // interference line
}
For ($ I = 0; $ I <$ how * 15; $ I ++) // draws background interference points
{
$ Color2 = ImageColorAllocate ($ im, mt_rand (0,255), mt_rand (0,255), mt_rand (0,255); // interference point color
ImageSetPixel ($ im, mt_rand (0, $ w), mt_rand (0, $ h), $ color2); // interference point
}

// Write the verification code string to the session

// $ This-> session-> set_userdata (array ($ this-> name => $ randcode ));

$ _ SESSION [$ this-> name] = $ randcode;
/* Drawing ends */
Imagegif ($ im );
ImageDestroy ($ im );
/* Drawing ends */
}
}
?>

Call php code:
The code is as follows:
Function verify_image (){
$ Conf ['name'] = 'verify _ code'; // used as the configuration parameter
$ This-> load-> library ('Lib _ captcha ', $ conf );
$ This-> lib_captcha-> show ();
$ Yzm_session = $ this-> session-> userdata ('verify _ code ');
Echo $ yzm_session;
}

Html code:
The code is as follows:

Verification code:

Change one

Incorrect verification code

Js code:
The code is as follows: