基于php验证码函数的使用示例

$_img = imagecreatetruecolor($_width,$_height);

$_white = imagecolorallocate($_img,250,250);

imagefill($_img,$_white);

$_gray = imagecolorallocate($_img,196,196);

imagerectangle($_img,$_width-1,$_height-1,$_gray);

for ($i=0; $i < 6; $i++) {
$_md_color = imagecolorallocate($_img,mt_rand(200,255),255));
imageline($_img,mt_rand(0,$_width),$_height),$_md_color);
}

for ($i=0; $i < 50; $i++) {
$_md_color = imagecolorallocate($_img,255));
imagestring($_img,1,mt_rand(1,$_width-5),$_height-5),"*",$_md_color);
}

for ($i=0; $i < $_code_length ; $i++) {
$_md_color = imagecolorallocate($_img,102),102));
imagestring($_img,5,$i * $_width/$_code_length+ mt_rand(1,10),$_height/2),$_SESSION["code"][$i],$_md_color);
}

header("Content-Type:image/png");

imagepng($_img);

imagedestroy($_img);
}