php 生成验证码程序

php 生成验证码程序

$consts = 'bcdfghjkmnpqrstwxyz';
 $vowels = 'aei23456789';
 for ($x = 0; $x < 6; $x++)
 {
  $const[$x] = substr($consts, mt_rand(0,strlen($consts)-1),1);
  $vow[$x] = substr($vowels, mt_rand(0,strlen($vowels)-1),1);
 }
 $radomstring = $const[0] . $vow[0] .$const[2] . $const[1] . $vow[1] . $const[3] . $vow[3] . $const[4];
 $_SESSION['checkcode'] = $string = substr($radomstring,0,4); //only display 4 str
 / t up image, the first number is the width and the second is the height
 $imageX = strlen($radomstring)*5.5; //the image width
 $imageY = 20;      //the image height
 $im = imagecreatetruecolor($imageX,$imageY);

 //creates two variables to store color
 $background = imagecolorallocate($im, rand(180, 250), rand(180, 250), rand(180, 250));
 $foregroundArr = array(imagecolorallocate($im, rand(0, 20), rand(0, 20), rand(0, 20)),
         imagecolorallocate($im, rand(0, 20), rand(0, 10), rand(245, 255)),
         imagecolorallocate($im, rand(245, 255), rand(0, 20), rand(0, 10)),
         imagecolorallocate($im, rand(245, 255), rand(0, 20), rand(245, 255)));
 $foreground2 = imagecolorallocatealpha($im, rand(20, 100), rand(20, 100), rand(20, 100),80);  
 $middleground = imagecolorallocate($im, rand(200, 160), rand(200, 160), rand(200, 160));
 $middleground2 = imagecolorallocatealpha($im, rand(180, 140), rand(180, 140), rand(180, 140),80);

 //fill image with bgcolor
 imagefill($im, 0, 0, imagecolorallocate($im, 250, 253, 254));
 //writes string
 imagestring($im, 5, 3, floor(rand(0,5))-1, $string[0], $foregroundArr[rand(0,3)]);
 imagestring($im, 5, 13, floor(rand(0,5))-1, $string[1], $foregroundArr[rand(0,3)]);
 imagestring($im, 5, 23, floor(rand(0,5))-1, $string[2], $foregroundArr[rand(0,3)]);
 imagestring($im, 5, 33, floor(rand(0,5))-1, $string[3], $foregroundArr[rand(0,3)]);
 for($i=0; $i  {
  if(mt_rand(0,ord(substr($string,$i,1)))%2 == 0)
  {
   $string{$i} = ' ';
  }
 }
 imagestring($im, 2, 2, 0, $string, $foreground2);
 //strikethrough

 $border = imagecolorallocate($im, 133, 153, 193);
 //imagefilledrectangle($aimg, 0, 0, $x_size - 1, $y_size - 1, $back);
 imagerectangle($im, 0, 0, $imageX - 1, $imageY - 1, $border);

 $pointcol = imagecolorallocate($im, rand(0,255), rand(0,255), rand(0,255));
 for ($i=0;$i<20;$i++)
 {
  imagesetpixel($im,rand(2,$imageX-2),rand(2,$imageX-2),$pointcol);
 }
 //rotate

 $middleground = imagecolorallocatealpha($im, rand(160, 200), rand(160, 200), rand(160, 200), 80);
 //random shapes
 for ($x=0; $x<15;$x++)
 {
  if(mt_rand(0,$x)%2==0)
  {
   imageline($im, rand(0, 120), rand(0, 120), rand(0, 120), rand(0, 120), $middleground);
   imageellipse($im, rand(0, 120), rand(0, 120), rand(0, 120), rand(0, 120), $middleground2);
  }
  else
  {
   imageline($im, rand(0, 120), rand(0, 120), rand(0, 120), rand(0, 120), $middleground2);
   imageellipse($im, rand(0, 120), rand(0, 120), rand(0, 120), rand(0, 120), $middleground);
  }
 }
 //output to browser
    header("content-type:image/pngrn");
 imagepng($im);
 imagedestroy($im);
?>