image.func.php

require_once 'string.func.php';

//通过GD库做验证码

function verifyImage($type=1,$length=4,$pixel=0,$line=0,$sess_name = "verify"){

    session_start();

    //创建画布

    $width = 80;

    $height = 28;

    $image = imagecreatetruecolor ( $width, $height );

    $white = imagecolorallocate ( $image, 255, 255, 255 );

    $black = imagecolorallocate ( $image, 0, 0, 0 );

    //用填充矩形填充画布

    imagefilledrectangle ( $image, 1, 1, $width - 2, $height - 2, $white );

    $chars = buildRandomString ( $type, $length );

    $_SESSION [$sess_name] = $chars;

    //$fontfiles = array ("SIMYOU.TTF");

    $fontfiles = array ("SIMYOU.TTF" );

    for($i = 0; $i < $length; $i ++) {

        $size = mt_rand ( 14, 18 );

        $angle = mt_rand ( - 15, 15 );

        $x = 5 + $i * $size;

        $y = mt_rand ( 20, 26 );

        $fontfile = "../fonts/" . $fontfiles [mt_rand ( 0, count ( $fontfiles ) - 1 )];

        $color = imagecolorallocate ( $image, mt_rand ( 50, 90 ), mt_rand ( 80, 200 ), mt_rand ( 90, 180 ) );

        $text = substr ( $chars, $i, 1 );

        imagettftext ( $image, $size, $angle, $x, $y, $color, $fontfile, $text );

    }

    if ($pixel) {

        for($i = 0; $i < 50; $i ++) {

            imagesetpixel ( $image, mt_rand ( 0, $width - 1 ), mt_rand ( 0, $height - 1 ), $black );

        }

    }

    if ($line) {

        for($i = 1; $i < $line; $i ++) {

            $color = imagecolorallocate ( $image, mt_rand ( 50, 90 ), mt_rand ( 80, 200 ), mt_rand ( 90, 180 ) );

            imageline ( $image, mt_rand ( 0, $width - 1 ), mt_rand ( 0, $height - 1 ), mt_rand ( 0, $width - 1 ), mt_rand ( 0, $height - 1 ), $color );

        }

    }

    header ( "content-type:image/gif" );

    imagegif ( $image );

    imagedestroy ( $image );

    }

string.func.php

function buildRandomString($type=1,$length=4){

    if ($type == 1) {

        $chars = join ( "", range ( 0, 9 ) );

    } elseif ($type == 2) {

        $chars = join ( "", array_merge ( range ( "a", "z" ), range ( "A", "Z" ) ) );

    } elseif ($type == 3) {

        $chars = join ( "", array_merge ( range ( "a", "z" ), range ( "A", "Z" ), range ( 0, 9 ) ) );

    }

    if ($length > strlen ( $chars )) {

        exit ( "字符串长度不够" );

    }

    $chars = str_shuffle ( $chars );

    return substr ( $chars, 0, $length );

}