PHP verification code code (latest modification, fully customized!)_PHP tutorial

session_start();
class Authnum {
//Image object, width, height, verification code length
private $im;
private $ im_width;
private $im_height;
private $len;
//Random string, y-axis coordinate value, random color
private $randnum;
private $y;
private $randcolor;
//The background color is red, green and blue, the default is light gray
public $red=238;
public $green=238;
public $blue=238;
/ **
* Optional settings: Verification code type, interference points, interference lines, Y-axis randomization
* Set to false to disable
**/
//The default is a mixture of uppercase and lowercase numbers, 1 2 3 represents lowercase, uppercase, and numeric respectively
public $ext_num_type='';
public $ext_pixel = false; //Interference point
public $ext_line = false; //Interference line
public $ext_rand_y= true; //Y-axis random
function __construct ($len=4,$im_width='',$im_height =25) {
// Verification code length, image width, and height are required data when instantiating the class
$this->len = $len; $im_width = $len * 15;
$ this->im_width = $im_width;
$this->im_height= $im_height;
$this->im = imagecreate($im_width,$im_height);
}
// Set the image background color, the default is light gray background
function set_bgcolor () {
imagecolorallocate($this->im,$this->red,$this->green,$this->blue ; an3 = '0123456789';
if ($this->ext_num_type == '') $str = $an1.$an2.$an3;
if ($this->ext_num_type == 1) $ str = $an1;
if ($this->ext_num_type == 2) $str = $an2;
if ($this->ext_num_type == 3) $str = $an3;
for ($i = 0; $i < $this->len; $i++) {
$start = rand(1,strlen($str) - 1);
$randnum .= substr( $str,$start,1);
}
$this->randnum = $randnum;
$_SESSION[an] = $this->randnum;
}
/ / Get the Y-axis of the verification code image
function get_y () {
if ($this->ext_rand_y) $this->y = rand(5, $this->im_height/5);
else $this->y = $this->im_height / 4 ;
}
// Get a random color
function get_randcolor () {
$this->randcolor = imagecolorallocate( $this->im,rand(0,100),rand(0,150),rand(0,200));
}
// Add interference points
function set_ext_pixel () {
if ($this ->ext_pixel) {
for($i = 0; $i < 100; $i++){
$this->get_randcolor();
imagesetpixel($this->im, rand()%100, rand()%100, $this->randcolor);
}
}
}
// Add interference line
function set_ext_line () {
if ($this->ext_line) {
for($j = 0; $j < 2; $j++){
$rand_x = rand(2, $this->im_width);
$rand_y = rand(2, $this->im_height);
$rand_x2 = rand(2, $this->im_width);
$rand_y2 = rand(2, $this-> im_height);
$this->get_randcolor();
imageline($this->im, $rand_x, $rand_y, $rand_x2, $rand_y2, $this->randcolor);
}
}
}
/**Create a verification code image:
* Create a canvas (__construct function)
* Set the canvas background ($this->set_bgcolor();)
* Get a random string ($this->get_randnum () ;)
* Write text to the image (imagestring function)
* Add interference points/lines ($this->set_ext_line(); $this->set_ext_pixel();)
* Output the image
**/
function create () {
$this->set_bgcolor();
$this->get_randnum ( );
for($i = 0; $i < $this->len; $i++){
$font = rand(4,6);
$x = $i/$ this->len * $this->im_width + rand(1, $this->len);
$this->get_y();
$this->get_randcolor();
imagestring($this->im, $font, $x, $this->y, substr($this->randnum, $i ,1), $this->randcolor);
}
$this->set_ext_line();
$this->set_ext_pixel();
header("content-type:image/png");
imagepng($this-> ;im);
imagedestroy($this->im); //Release image resources
}
}//end class
/**Methods to use the verification code class:
* $an = new Authnum (verification code length, image width, image height);
* When instantiated without parameters, the default is a four-digit regular size of 60*25 Verification code image
* Method to detect verification code on form page, compare whether $_SESSION[an] is equal to $_POST[Verification code text box ID]
* Optional configuration:
* 1. Verification code type: $an->ext_num_type=1; A value of 1 is a lowercase type, 2 is an uppercase type, and 3 is a numeric type
* 2. Interference point: $an->ext_pixel = false; A value of false means no interference is added. Point
* 3. Interference line: $an->ext_line = false; A value of false means no interference line will be added
* 4. Y-axis randomization: $an->ext_rand_y = false; A value of false means no interference line is added. The Y-axis randomization of the picture is not supported
* 5. Picture background: change the values ​​of the three member variables $red, green and $blue
**/
$an = new Authnum();
$an->ext_num_type='';
$an->ext_pixel = true ; //Interference point
$an->ext_line = false; //Interference line
$an->ext_rand_y= true; //Y-axis random
$an->green = 238;
$an->create();
?>