/cmsdemo/Include/GetVerifyImg.php

<?php

$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

$fontSize = 15;													//定义字体大小

$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("../Include/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

 */

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;

}

exit;

?>