inserire il controllo captka nel form

[rocco.mod]

/** by Antonio Palermi 2007 [url]www.captcha.biz[/url] */
session_start();
header("Content-Type: image/png");     // or image/jpg

// custom parameters
$box_w                 = 125;            // Width of the captha box
$box_h                 = 35;            // Height of the captha box
$font                 = 'arial.ttf';    // Used font
$font_size             = 24;             // Size of the font
$font_angle         = 0;             // Angle of text
$font_x             = 10;             // Margin left
$font_y             = 5;             // Margin top
$color_background     = 'black';         // Bakground color: black, white, green, blu, red
$color_text         = 'white';        // Text color:         black, white, green, blu, red
$color_lines         = 'white';        // Lines color:        black, white, green, blu, red
$thickness            = 1;            // Thickness of lines
$lines_angle        = 5;            // angle of lines (from 1 to 10)
$lines_number        = 5;            // numbers of lines

// set a passcode 
$pass = '';
$nchar = 5;                            // number of characters in image
for($i=1;$i<=$nchar;$i++){
    $charOnumber = rand(1,2);
    if($charOnumber == 1){
        $chars = 'ABEFHKMNRVWX';    // custom used characters
        $n = strlen($chars)-1;
        $x = rand(1,$n);
        $char = substr($chars,$x,1);
        $pass .= $char;
    } else {
        //$number = rand(3,7);
        $numbers = array(1,2,3,4,7);    // custom used numbers
        $n = count($numbers)-1;
        $number = $numbers[rand(1,$n)];
        $pass .= $number;
    }
}

// set the session 
$_SESSION["pass"] = $pass;

// create the image resource
$image = ImageCreatetruecolor($box_w,$box_h);

// set colors
$white     = ImageColorAllocate($image, 255, 255, 255);
$black     = ImageColorAllocate($image, 0, 0, 0);
$green     = ImageColorAllocate($image, 0, 255, 0);
$red     = ImageColorAllocate($image, 255, 0, 0);
$blu     = ImageColorAllocate($image, 0, 0, 255);

switch($color_background){
    case 'black':
    $color_background = $black;
    break;
    case 'white':
    $color_background = $white;
    break;
    case 'green':
    $color_background = $green;
    break;
    case 'blu':
    $color_background = $blu;
    break;
    case 'red':
    $color_background = $red;
    break;
    default:
    $color_background = $black;
}
switch($color_text){
    case 'black':
    $color_text = $black;
    break;
    case 'white':
    $color_text = $white;
    break;
    case 'green':
    $color_text = $green;
    break;
    case 'blu':
    $color_text = $blu;
    break;
    case 'red':
    $color_text = $red;
    break;
    default:
    $color_text = $black;
}
switch($color_lines){
    case 'black':
    $color_lines = $black;
    break;
    case 'white':
    $color_lines = $white;
    break;
    case 'green':
    $color_lines = $green;
    break;
    case 'blu':
    $color_lines = $blu;
    break;
    case 'red':
    $color_lines = $red;
    break;
    default:
    $color_lines = $white;
}

// set background 
imagefill($image, 0, 0, $color_background);

// set text 
imagettftext($image, $font_size, $font_angle, $font_x, $font_size + $font_y, $color_text, $font, $pass);

// set lines
imagesetthickness($image,$thickness);

$step = $box_w/$lines_number;

switch($lines_angle){
    case 1:
    $start     = 5;
    $end    = 5;
    break;
    case 2:
    $start     = 5;
    $end    = 10;
    break;
    case 3:
    $start     = 5;
    $end    = 15;
    break;
    case 4:
    $start     = 5;
    $end    = 20;
    break;
    case 5:
    $start     = 5;
    $end    = 25;
    break;
    case 6:
    $start     = 5;
    $end    = 30;
    break;
    case 7:
    $start     = 5;
    $end    = 35;
    break;
    case 8:
    $start     = 5;
    $end    = 40;
    break;
    case 9:
    $start     = 5;
    $end    = 45;
    break;
    case 10:
    $start     = 5;
    $end    = 50;
    break;
}

$a = $start;
$b = $end;

for($i=1;$i<=$lines_number;$i++){
    $l = $start;
    $l1 = $end;
    imageline($image, $l, 1, $l1, $box_h, $color_lines);
    $start = $a + ($step*$i-1);
    $end = $start + $b;
}

// created image 
imagejpeg($image);
imagedestroy($image); 

adesso vorrei inserire i controlli nel files mailform soltanto che gli errori si dovrebbero vedere nella pag del form