WAVY CAPTCHA

<?php
/**
 * Wavy Captcha
 * @author : Johan Barbier <johan.barbier@gmail.com>
 * Original idea and code from Coockiesch : http://www.phpcs.com/codes/IMAGE-ANTI-SPAM_38969.aspx
 * Algorithm for wavy stuff from Kruglov Sergei : http://www.phpclasses.org/browse/package/3193.html
 * I just mixed both, basically
 */
// definitions
$foreground_color = array(mt_rand(0,100), mt_rand(0,100), mt_rand(0,100));
$background_color = array(mt_rand(200,255), mt_rand(200,255), mt_rand(200,255));

$strlen = 5;

$width = $strlen * 30 + 20;
$height = 60;

$iLinesAndArcs = 10;

$iFontMax = 20;
$iFontMin = 25;
$iFontRotationMin = -30;
$iFontRotationMax = 30;
$iFontBaseLine = $height - 15;
$iFontSpace = 20;
$iFontMult = 30;

$rMin = 180;
$rMax = 255;
$vMin = 180;
$vMax = 255;
$bMin = 180;
$bMax = 255;

$sTTFFontPath = 'verdana.ttf';

// création
$img = imagecreatetruecolor($width, $height);
$img2 = imagecreatetruecolor($width, $height);
imageantialias( $img, 1 );

$foreground = imagecolorallocate($img, $foreground_color[0], $foreground_color[1], $foreground_color[2]);
$background = imagecolorallocate($img, $background_color[0], $background_color[1], $background_color[2]);

imagefill ($img, 0,0,$background);

$rand1=mt_rand(900000,1000000)/10000000;
$rand2=mt_rand(900000,1000000)/10000000;
$rand3=mt_rand(900000,1000000)/10000000;
$rand4=mt_rand(900000,1000000)/10000000;
// phases
$rand5=mt_rand(0,3141592)/500000;
$rand6=mt_rand(0,3141592)/500000;
$rand7=mt_rand(0,3141592)/500000;
$rand8=mt_rand(0,3141592)/500000;
// amplitudes
$rand9=mt_rand(330,420)/110;
$rand10=mt_rand(330,450)/110;

for( $i = 0; $i < $iLinesAndArcs; $i++ ) {
	$r = mt_rand ($rMin, $rMax);
	$v = mt_rand ($vMin, $vMax);
	$b = mt_rand ($bMin, $bMax);
	$color = imagecolorallocate($img, $r, $v, $b);
	imageline( $img, mt_rand(0, $width), mt_rand(0, $height), mt_rand(0, $width), mt_rand(0, $height), $color);
	imagearc($img, mt_rand(0, $width), mt_rand(0, $height), mt_rand(0, $width), mt_rand(0, $height), 0, 360, $color);
}

// chaine
$string = 'ABCDEFGHIJKLMNPQRSTUVWXYZ23456789';
$chaine = '';
for( $i = 0; $i < $strlen; $i++ )
$chaine .= $string[ mt_rand( 0, strlen ($string) - 1 ) ];

$_SESSION['test'] = $chaine;

for( $i = 0; $i < $strlen; $i++ ) {
	imagettftext( $img, mt_rand($iFontMax, $iFontMin), mt_rand($iFontRotationMin, $iFontRotationMax), $i * $iFontMult + $iFontSpace, $iFontBaseLine, $foreground, $sTTFFontPath, $chaine[$i] );
}

//wavy stuff
for($x=0;$x<$width;$x++){
    for($y=0;$y<$height;$y++){
        $sx=$x+(sin($x*$rand1+$rand5)+sin($y*$rand3+$rand6))*$rand9-$width/2+($width/2)+1;
        $sy=$y+(sin($x*$rand2+$rand7)+sin($y*$rand4+$rand8))*$rand10;

        if($sx<0 || $sy<0 || $sx>=$width-1 || $sy>=$height-1){
            $color=255;
            $color_x=255;
            $color_y=255;
            $color_xy=255;
        }else{
            $color=imagecolorat($img, $sx, $sy) & 0xFF;
            $color_x=imagecolorat($img, $sx+1, $sy) & 0xFF;
            $color_y=imagecolorat($img, $sx, $sy+1) & 0xFF;
            $color_xy=imagecolorat($img, $sx+1, $sy+1) & 0xFF;
        }

        if($color==0 && $color_x==0 && $color_y==0 && $color_xy==0){
            $newred=$foreground_color[0];
            $newgreen=$foreground_color[1];
            $newblue=$foreground_color[2];
        }else if($color==255 && $color_x==255 && $color_y==255 && $color_xy==255){
        	$newred=$background_color[0];
            $newgreen=$background_color[1];
            $newblue=$background_color[2];
        }else{
            $frsx=$sx-floor($sx);
            $frsy=$sy-floor($sy);
            $frsx1=1-$frsx;
            $frsy1=1-$frsy;

            $newcolor=(
                $color*$frsx1*$frsy1+
                $color_x*$frsx*$frsy1+
                $color_y*$frsx1*$frsy+
                $color_xy*$frsx*$frsy);

            if($newcolor>255) $newcolor=255;
            $newcolor=$newcolor/255;
            $newcolor0=1-$newcolor;


            $newred=$newcolor0*$foreground_color[0]+$newcolor*$background_color[0];
            $newgreen=$newcolor0*$foreground_color[1]+$newcolor*$background_color[1];
            $newblue=$newcolor0*$foreground_color[2]+$newcolor*$background_color[2];
        }

        imagesetpixel($img2, $x, $y, imagecolorallocate($img2, $newred, $newgreen, $newblue));
    }
}


// bordure
$noir = imagecolorallocate ($img2,0,0,0);
imageline( $img2, 0, 0, $width, 0, $noir );
imageline( $img2, 0, $height - 1, $width, $height - 1, $noir );
imageline( $img2, 0, 0, 0, $height, $noir );
imageline( $img2, $width - 1, 0, $width - 1, $height, $noir );


// header: image
header("Content-type: image/png");
imagepng( $img2 );
imagedestroy( $img2 );

?>