determinant3/ucapcha

<?php
class determinant3
{

    function generate_image($canvas)
    {
        global $captcha_font_path,$captcha_img_path;
        $hit = "Считай детерминант, неуч!";
        $a11=rand(0,9);
        $a12=rand(0,9);
        $a13=rand(0,9);
        $a21=rand(0,9);
        $a22=rand(0,9);
        $a23=rand(0,9);
        $a31=rand(0,9);
        $a32=rand(0,9);
        $a33=rand(0,9);
        $color = imagecolorallocate($canvas, rand(100,255), rand(100,255), rand(100,255));
        imageline($canvas, 20, 10, 20, 60, $color);
        imageline($canvas, 160, 10, 160, 60, $color);
        $rand=" =?";
        for($i=0;$i<strlen($rand);$i++)
        {
            $color = imagecolorallocate($canvas, rand(100,255), rand(100,255), rand(100,255));
            imagefttext($canvas, 20, rand(-45,45), 144+20*$i, 50, $color, $captcha_font_path."/LiberationMono-Bold.ttf", $rand[$i]);
        }
        $color = imagecolorallocate($canvas, rand(100,255), rand(100,255), rand(100,255));
        imagefttext($canvas, 16, rand(-5,5), 40, 20, $color, $captcha_font_path."/LiberationMono-Bold.ttf", $a11);
        imagefttext($canvas, 16, rand(-5,5), 80, 20, $color, $captcha_font_path."/LiberationMono-Bold.ttf", $a12);
        imagefttext($canvas, 16, rand(-5,5), 120, 20, $color, $captcha_font_path."/LiberationMono-Bold.ttf", $a13);
        imagefttext($canvas, 16, rand(-5,5), 40, 35, $color, $captcha_font_path."/LiberationMono-Bold.ttf", $a21);
        imagefttext($canvas, 16, rand(-5,5), 80, 35, $color, $captcha_font_path."/LiberationMono-Bold.ttf", $a22);
        imagefttext($canvas, 16, rand(-5,5), 120, 35, $color, $captcha_font_path."/LiberationMono-Bold.ttf", $a23);
        imagefttext($canvas, 16, rand(-5,5), 40, 50, $color, $captcha_font_path."/LiberationMono-Bold.ttf", $a31);
        imagefttext($canvas, 16, rand(-5,5), 80, 50, $color, $captcha_font_path."/LiberationMono-Bold.ttf", $a32);
        imagefttext($canvas, 16, rand(-5,5), 120, 50, $color, $captcha_font_path."/LiberationMono-Bold.ttf", $a33);
        imagefttext($canvas, 8, rand(-5,5), 15, 75, $color, $captcha_font_path."/LiberationMono-Bold.ttf", $hit);
        $nme=$this->ucaptcha->get_filename();
        imagepng($canvas);
        //$ans=($a*$d)-($b*$c);
        $ans=($a11*$a22*$a33) - ($a11*$a23*$a32) - ($a12*$a21*$a33) + ($a12*$a23*$a31) + ($a13*$a21*$a32) - ($a13*$a22*$a31)
        $captcha[0]=$nme;
        $captcha[1]=$ans;
        return $captcha;
    }
}
?>