验证码文件GetVerifyImg.php

<?php
session_start();
function GetVerify($length)
{
$strings = Array('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');
$chrNum = "";
$count = count($strings);
for ($i = 1; $i <= $length; $i++) {//循环随机取字符生成字符串
$chrNum .= $strings[rand(0,$count-1)];
}
return $chrNum;
}
$fontSize = 15; //定义字体大小
$length = 4; //定义字符串长度
$strNum = GetVerify($length); //获取一个随机字符串
$_SESSION['verify'] = $strNum; //付值给session
$width = 70; //定义图片宽度
$height = 24; //定义图片高度
$im = imagecreate($width,$height); //生成一张指定宽高的图片
$backgroundcolor = imagecolorallocate ($im, 255, 255, 255);//生成背景色
$frameColor = imageColorAllocate($im, 150, 150, 150);//生成边框色
$font = realpath("arial.ttf"); //提取字体文件，开始写字
for($i = 0; $i < $length; $i++) {
$charY = ($height+9)/2 + rand(-1,1);//定义字符Y坐标
$charX = $i*15+8;//定义字符X坐标
//生成字符颜色
$text_color = imagecolorallocate($im, mt_rand(50, 200), mt_rand(50, 128), mt_rand(50, 200));
$angle = rand(-20,20);//生成字符角度
//写入字符
imageTTFText($im, $fontSize, $angle, $charX,  $charY, $text_color, $font, $strNum[$i]);
}
for($i=0; $i <= 5; $i++) { //循环画背景线
$linecolor = imagecolorallocate($im, mt_rand(0, 255), mt_rand(0, 255), mt_rand(0, 255));
$linex = mt_rand(1, $width-1);
$liney = mt_rand(1, $height-1);
imageline($im, $linex, $liney, $linex + mt_rand(0, 4) - 2, $liney + mt_rand(0, 4) - 2, $linecolor);
}
for($i=0; $i <= 32; $i++) { //循环画背景点,生成麻点效果
$pointcolor = imagecolorallocate($im, mt_rand(0, 255), mt_rand(0, 255), mt_rand(0, 255));
imagesetpixel($im, mt_rand(1, $width-1), mt_rand(1, $height-1), $pointcolor);
}
imagerectangle($im, 0, 0, $width-1 , $height-1 , $frameColor);//画边框
ob_clean();
header('Content-type: image/png');
imagepng($im);
imagedestroy($im);
/**
 * 功能：生成随机字符串
 */
exit;
?>