<?php
error_reporting(0);
session_start();
session_register('code');
$_SESSION['code'] = '';

$width = '60'; //图片宽
$height = '30'; //图片高

$textall = array_merge_recursive(range('a', 'z'));
for ($i = 0; $i < 4; $i++) {
	$tmptext = rand(0, 9);
	$randtext = $textall[$tmptext];
	$code .= $randtext;
}

$_SESSION['code'] = $code;

@header("Expires: -1");
@header("Cache-Control: no-store, private, post-check=0, pre-check=0, max-age=0", FALSE);
@header("Pragma: no-cache");

if (function_exists('imagecreate') && function_exists('imagecolorset') && function_exists('imagecopyresized') && function_exists('imagecolorallocate') && function_exists('imagesetpixel') && function_exists('imagechar') && function_exists('imagecreatefromgif') && function_exists('imagepng')) {
	$im = imagecreate($width, $height);
	$backgroundcolor = imagecolorallocate($im, 255, 255, 255);

	$numorder = array(1, 2, 3, 4);
	shuffle($numorder);
	$numorder = array_flip($numorder);

	for ($i = 1; $i <= 4; $i++) {
		$x = $numorder[$i] * 13 + mt_rand(0, 4) - 2;
		$y = mt_rand(0, 3);
		$text_color = imagecolorallocate($im, mt_rand(50, 255), mt_rand(50, 128), mt_rand(50, 255));
		imagechar($im, 5, $x + 5, $y + 3, $code[$numorder[$i]], $text_color);
	}
	
	$linenums = mt_rand(10, 32);
	for ($i = 0; $i <= $linenums; $i++) {
		$linecolor = imagecolorallocate($im, mt_rand(0, 255), mt_rand(0, 255), mt_rand(0, 255));
		$linex = mt_rand(0, $width);
		$liney = mt_rand(0, $height);
		imageline($im, $linex, $liney, $linex + mt_rand(0, 4) - 2, $liney + mt_rand(0, 4) - 2, $linecolor);
	}

	for ($i = 0; $i <= 40; $i++) {
		$pointcolor = imagecolorallocate($im, mt_rand(50, 255), mt_rand(50, 255), mt_rand(50, 255));
		imagesetpixel($im, mt_rand(0, $width), mt_rand(0, $height), $pointcolor);
	}

	$bordercolor = imagecolorallocate($im , 150, 150, 150);
	imagerectangle($im, 0, 0, $width - 1, $height - 1, $bordercolor);

	header('Content-type: image/png');
	imagepng($im);
	imagedestroy($im);
} else {
	$numbers = array (
		0 => array('3c','66','66','66','66','66','66','66','66','3c'),
		1 => array('1c','0c','0c','0c','0c','0c','0c','0c','1c','0c'),
		2 => array('7e','60','60','30','18','0c','06','06','66','3c'),
		3 => array('3c','66','06','06','06','1c','06','06','66','3c'),
		4 => array('1e','0c','7e','4c','2c','2c','1c','1c','0c','0c'),
		5 => array('3c','66','06','06','06','7c','60','60','60','7e'),
		6 => array('3c','66','66','66','66','7c','60','60','30','1c'),
		7 => array('30','30','18','18','0c','0c','06','06','66','7e'),
		8 => array('3c','66','66','66','66','3c','66','66','66','3c'),
		9 => array('38','0c','06','06','3e','66','66','66','66','3c')
	);

	for ($i = 0; $i < 10; $i++) {
		for ($j = 0; $j < 6; $j++) {
			$a1 = substr('012', mt_rand(0, 2), 1).substr('012345', mt_rand(0, 5), 1);
			$a2 = substr('012345', mt_rand(0, 5), 1).substr('0123', mt_rand(0, 3), 1);
			mt_rand(0, 1) == 1 ? array_push($numbers[$i], $a1) : array_unshift($numbers[$i], $a1);
			mt_rand(0, 1) == 0 ? array_push($numbers[$i], $a1) : array_unshift($numbers[$i], $a2);
		}
	}

	$bitmap = array();
	for ($i = 0; $i < 20; $i++) {
		for ($j = 0; $j < 4; $j++) {
			$n = substr($code, $j, 1);
			$bytes = $numbers[$n][$i];
			$a = mt_rand(0, 14);
			switch ($a) {
				case 1: str_replace('9', '8', $bytes); break;
				case 3: str_replace('c', 'e', $bytes); break;
				case 6: str_replace('3', 'b', $bytes); break;
				case 8: str_replace('8', '9', $bytes); break;
				case 0: str_replace('e', 'f', $bytes); break;
			}
			array_push($bitmap, $bytes);
		}
	}

	for ($i = 0; $i < 8; $i++) {
		$a = substr('012', mt_rand(0, 2), 1) . substr('012345', mt_rand(0, 5), 1);
		array_unshift($bitmap, $a);
		array_push($bitmap, $a);
	}

	$image = pack('H*', '424d9e000000000000003e000000280000002000000018000000010001000000'.
			'0000600000000000000000000000000000000000000000000000FFFFFF00'.implode('', $bitmap));

	header('Content-Type: image/png');
	echo $image;
}
?>