php simple verification code

Class VeriFyimg {

public $ fontsize = 15; // Define font size

public $ length = 4; // Define string length

public $ width = 70; // Define the width of the picture width

public $height = 30; //Define the image height

public $im = null; //Generate an image with a specified width and height

public $font = 'C:/Windows/Fonts/Arial.TTF';

public $strNum = "";

public function Build() {

$strings = Array ('1', '2','3', '4', '5', '6', '7' , 'a', 'b', 'c', 'd', 'e', ​​'f', 'h', 'i', 'j', 'k', 'm', 'n', ' p', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y' );

// $strNum = "";

$count = count ( $strings );

for($i = 1; $i <= $this->length; $i ++) { //Loop through random characters to generate a string

$strNum .= $ strings [rand ( 0, $count - 1 )];

}

session_start ();

$_SESSION ["verifycode"] = $strNum;

$this->im = imagecreate ( $this-> ;width, $this->height );

$backgroundcolor = imagecolorallocate ( $this->im, 255, 255, 255 ); //Generate background color

$frameColor = imageColorAllocate ( $this->im , 0, 255, 0 );

for($i = 0; $i < $this->length; $i ++) {

$charY = ($this->height + 9) / 2 + rand ( - 1, 1 ); //Define the Y coordinate of the character

$charX = $i * 15 + 8; //Define the X coordinate of the character

// $text_color = imagecolorallocate($this->im, 255, 0, 0); ), mt_rand ( 50, 200 ) );

$angle = rand ( - 20, 20 ); //Generate character angle

//Write characters

imagettftext ( $this->im, $this->fontSize, $angle, $charX, $charY, $text_color, $this->font, $strNum [$i] );

}

for($i = 0; $i <= 5; $i ++) { //Loop to draw background lines

$linecolor = imagecolorallocate ( $this->im, mt_rand ( 0, 255 ), mt_rand ( 0, 255 ), mt_rand ( 0, 255 ) );

$linex = mt_rand ( 1, $this->width - 1 );

$liney = mt_rand ( 1, $this->height - 1 );

imageline ( $this->im, $linex, $liney, $linex + mt_rand ( 0, 4 ) - 2, $liney + mt_rand (0, 4) - 2, $linecolor );

}

for($i = 0; $i <= 32; $i ++) { //Loop to draw background points, Generate pitting effect

$pointcolor = imagecolorallocate ( $this->im, mt_rand ( 0, 255 ), mt_rand ( 0, 255 ), mt_rand ( 0, 255 ) );

imagesetpixel ( $this->im , mt_rand ( 1, $this->width - 1 ), mt_rand ( 1, $this->height - 1 ), $pointcolor );

}

imagerectangle ( $this->im, 0, 0 , $this->width - 1, $this->height - 1, $frameColor ); //Draw a border

ob_clean ();

header ( 'Content-type:image/png' );

imagepng ( $this->im );

imagedestroy ( $this->im );

}

}

$img = new VerifyImg ();

$img->Build ();

?>