Captcha image script problem

ppowell

I wrote a small procedural script (OO would have been better but time constraints dictated otherwise) that produces a captcha image

Online: http://valsignalandet.com/images/captcha.php

However, while the images are being produced, the text appears in random colors from black to white to gray, and I can't seem to control that in spite of hard-coding the background and foreground colors, furthermore, the text also randomly appears within the image positioned differently each time.

Here is the code:

<?php

session_start();

if (!function_exists('randstring')) @include('/users/ppowell/web/functions.inc.php');

if (!$_SESSION['rand_code']) {
    $_SESSION['rand_code'] = @randstring(6);
}
$text = $_SESSION['rand_code'];


$image = @imagecreatetruecolor(90, 30);

$bgColor = @imagecolorallocate($image, 180, 180, 180);

$fgColor = @imagecolorallocate($image, 75, 75, 75);
$width    = (@imagesx($image) - 7.5 * $text) / 2;
$height = (@imagesy($image) - 7.5) / 2;

@imagefilledrectangle($image, 0, 0, 90, 30, $bgColor);
@imagestring($image, rand(3, 5), $width, $height, $text, $fgColor);

unset($_SESSION['rand_code'], $text);
session_unregister('rand_code');

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

?>

Any ideas as to why this is happening?
Thanks

NogDog

The rand(3, 5) as the 2nd parameter to the imagestring() function is randomly selecting the font to be used. Since each font is a different size, its baseline is pushed down a different amount from the specified x/y location. As far as the different coloring, I think that may just be a difference in how the various fonts are rendered.

ppowell

I managed to change it to use only one font, however, I cannot seem to escape the offset of any font I pick, they're all too far to the right of the image, how can I change that?

<?php

session_start();

if (!function_exists('randstring')) @include('/users/ppowell/web/functions.inc.php');

if (!$_SESSION['rand_code']) {
    $_SESSION['rand_code'] = @randstring(6);
}
$text = $_SESSION['rand_code'];


$image = @imagecreatetruecolor(120, 30);

$bgColor = @imagecolorallocate($image, 180, 180, 180);

$fgColor = @imagecolorallocate($image, 75, 75, 75);
$width    = (@imagesx($image) - 7.5 * $text) / 2;
$height = (@imagesy($image) - 7.5) / 2;

@imagefilledrectangle($image, 0, 0, 120, 30, $bgColor);
@imagestring($image, 6, $width, $height, $text, $fgColor);


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

?>