生成验证码

[php]代码库

<?php
session_start(); //MUST START SESSION 
$string_length = 4; //NUMBER OF CHARS TO DISPLAY 
$large_letters = array('m','w');
$rand_string = ''; 
 
for ($i=0; $i<$string_length; $i++) { 
  //PICK A RANDOM LOWERCASE LETTER USING ASCII CODE 
  $rand_string .= chr(rand(97,122)); 
}
 
//IMAGE VARIABLES 
//$width = 100; 
//$height = 36; 
$width = 60; 
$height = 25; 

 
//INIT IMAGE 
$img = imagecreatetruecolor($width, $height); 
 
//ALLOCATE COLORS 
$black = imagecolorallocate($img, 0, 0, 0); 
$gray = imagecolorallocate($img, 110, 110, 110); 
$medgray = imagecolorallocate($img, 180, 180, 180); 
$lightgray = imagecolorallocate($img, 220, 220, 220); 
//FILL BACKGROUND
imagefilledrectangle($img, 0, 0, $width, $height, $lightgray); 
 
//ADD NOISE - DRAW background squares
$square_count = 6;
for ($i = 0; $i < 10; $i++) {
  $cx = (int)rand(0, $width/2);
  $cy = (int)rand(0, $height);
  $h  = $cy + (int)rand(0, $height/5);
  $w  = $cx + (int)rand($width/3, $width);
  imagefilledrectangle($img, $cx, $cy, $w, $h, $medgray); 
}
 
//ADD NOISE - DRAW ELLIPSES
$ellipse_count = 5;
for ($i = 0; $i < $ellipse_count; $i++) {
  $cx = (int)rand(-1*($width/2), $width + ($width/2));
  $cy = (int)rand(-1*($height/2), $height + ($height/2));
  $h  = (int)rand($height/2, 2*$height);
  $w  = (int)rand($width/2, 2*$width);
  imageellipse($img, $cx, $cy, $w, $h, $gray);
}
 
//REPLACE THIS WITH THE FONT YOU UPLOAD 
$font = '../tiff/DejaVuSerifCondensed-Italic.ttf';
//$font = 'monofont.ttf'; 
$font_size = 16;
 
//CALC APPROX LOCATION - CUSTOMIZED FOR ABOVE FONT 
$y_value = ($height/2) + ($font_size/2); 
$x_value = 0;
 
//DRAW STRING USING TRUE TYPE FUNCTION 
 
for ($i = 0; $i < $string_length; $i++) {
  $chr = substr($rand_string, $i, 1);
  $x_value += 3 * ($font_size/5); 
  imagettftext($img, $font_size, 0, $x_value, $y_value, $black, $font, $chr); 
  //check to see if larger than normal letters, if so add more horiz space
  if (in_array($chr, $large_letters)) {
    $x_value += 4;
  }
}
 
$auth_type = isset($_REQUEST['type'])?$_REQUEST['type']:''; 
if($auth_type=="login")
{
	$_SESSION['authcode_login']=$rand_string;
}
else
{
	//$_SESSION['encoded_captcha'] = md5($rand_string . 'my_secret_key'); 
	$_SESSION['authcode']=$rand_string; 
}
 
//OUTPUT IMAGE HEADER AND SEND TO BROWSER 
header("Content-Type: image/png"); 
imagepng($img); 
?>