Problem with captcha image not showing

[jeddiki]

Hi,
I have a captcha script which should pick up a background image and add some random letters to it and re-display

This is the part of the form that the captcha image is part of:

<span >Verification Image:</span>
<span ><img src="captcha.php" id="captcha" />
<a href="#renew" onclick="javascript: document.getElementById('captcha').src = 'captcha.php?' + Math.random();">refresh</a> </span>

<span >Enter 8 character key:</span>
<span ><input type="text" name="imgver" id="imgver" onkeyup ="this.value=this.value.toUpperCase()"></span>

<input class="button2" type="submit" value="Give Me Free Entry Now"/>

And here is the captcha script that is called:

#since we are storing our data using Sessions, we need to start a session
session_start();
#$bg_image is the image that will be used for the background of our captcha
#you will have to replace the value with your bg image.
$bg_image = "images/cap02.png";
#we're going to put some lines throughout the image to make it a bit harder for bots to crack
#to color the lines, we need to fill in the color fields using RGB values (0-255 for each color)
$line_color = array(
"R" => 150,
"G" => 150,
"B" => 150
);
#set the number of line to display in our captcha
$numLines = 5;
#set the length of the key to display in our captcha
$keyLength = 6;
#set the color of the text in our captcha
$textcolor = array(
"R" => 0,
"G" => 255,
"B" => 0
);

#get some file attribures of our bg image, all we are going to use is witdth and height.
list($width, $height, $type, $attr) = getimagesize($bg_image);

#using PHP's GD Library, we're going to create our base captcha, which starts with our BG image.
$captcha = imagecreatefrompng($bg_image);
#sets the color for our key, the color was defined above.
$keycol = imagecolorallocate($captcha, $textcolor["R"],$textcolor["G"],$textcolor["B"]);
#start a loop to add our lines to our captcha
for($i = 0; $i < $numLines; $i++)
{
    $line = imagecolorallocate($captcha,$line_color["R"],$line_color["G"],$line_color["B"]);
    imageline($captcha,rand(0, $width),rand(0,$height),rand(0, $width),rand(0,$height),$line);
}
#generate our random key
$string = GenKey($keyLength);
#add our random key to our captcha
imagestring($captcha, 9, rand(1, 30), rand(1, 15), $string, $keycol);
#encrypt our key and add it to our session data.
$_SESSION['key'] = md5($string);
#send HTTP header to tell client we're going to display an image.
header("Content-type: image/png");
#dsplay image
imagepng($captcha);

function GenKey ($length)
{
    #define the letter / number that will be used in our key.
    $chars = "123456789ABCDEFGHIJKLMNPQRSTUVWXYZ";
    #start a loop to make the key.
    for($i = 0; $i < $length; $i++)
    {
        #pick a random start place in the string
        $rand_start = rand(1, strlen($chars) - 1);
        #add this character to our key
        $key .= substr($chars, $rand_start, 1);
    }
    #return our key
    return $key;
}
?>

I have a background image that is here:


image

As far as I can see, everything should work but I get nothing displayed at all.

Can anyone spot my errors ?
Thanks for helping.

[Atli]

Hi.

The captcha.php script is probably printing some errors. Try commenting out the header and navigate to the capatcha.php file in your browser. See if there are any errors.

[jeddiki]

Thanks for your reply, but I am not sure what you mean or how to do it :(

[Atli]

Line #44 in the code you posted. Remove it.
You can simply put # or // in front of it to comment it out.

Then open the script in your browser.

http://www.devchoice.info/captcha.php

That should tell you why your image isn't showing like it should.

[jeddiki]

OK ,
thanks for explaining that.

It shows an error:
Notice: Undefined variable: key in /home/chosy/public_html/captcha.php on line 64

That line 64 refers to:

$key .= substr($chars, $rand_start, 1);

So its missing the $key variable,
Am I supposed to suply that variable somehow ?

[Markus]

OK ,
thanks for explaining that.

It shows an error:
Notice: Undefined variable: key in /home/chosy/public_html/captcha.php on line 64

That line 64 refers to:

$key .= substr($chars, $rand_start, 1);

So its missing the $key variable,
Am I supposed to suply that variable somehow ?

Because you haven't defined the variabled, you can't add to it using '.='

Add $key = ""; to your GenKey method (to the top of it).

[jeddiki]

Thanks Marcus,

I have dropped it in here: (line 14 - 15 )

#since we are storing our data using Sessions, we need to start a session
session_start();
#$bg_image is the image that will be used for the background of our captcha
#you will have to replace the value with your bg image.
$bg_image = "images/cap02.png";
#we're going to put some lines throughout the image to make it a bit harder for bots to crack
#to color the lines, we need to fill in the color fields using RGB values (0-255 for each color)
$line_color = array(
"R" => 150,
"G" => 150,
"B" => 150
);

#initialise the key
$key = "";

#set the number of line to display in our captcha
$numLines = 5;

#set the length of the key to display in our captcha
$keyLength = 6;

#set the color of the text in our captcha
$textcolor = array(
"R" => 0,
"G" => 255,
"B" => 0
);

Is that what you meant ?

[Markus]

Nope, I meant inside your GenKey method, like so:

function GenKey ($length)
{
    # key
    $key = "";
    #define the letter / number that will be used in our key.
    $chars = "123456789ABCDEFGHIJKLMNPQRSTUVWXYZ";
    #start a loop to make the key.
    for($i = 0; $i < $length; $i++)
    {
        #pick a random start place in the string
        $rand_start = rand(1, strlen($chars) - 1);
        #add this character to our key
        $key .= substr($chars, $rand_start, 1);
    }
    #return our key
    return $key;
}

Does that work now?

[jeddiki]

Ah ha
Good job I asked ;)

When I run it I get this:

�PNG ��� IHDR���x���� ��h�M����IDATh ���y��U} ����o��{�-��4 M�(��R���N,��� %1�X��lj����2� 3��m�$�)*��Xf *(��ұ��n�_� ~�}w�mg�?^�hh�( Ƅ�n������o�{~� s.:�7xYo�W��ڛs Z�O��j��>��"� �6"�ou��+�ke� �s�s��4�m����S ��H�`n�$���"�2ވ ���k���x�<�d�<( �ה��3�S����Ѧ� �`kk}0�� ��-V���#��S��O�� �̨rd�mq���S �4W5�����!� ��51C�M=�&� �'7c�оC����L{�� 3�

so maybe thats working

I'll take out the comment out at:
#header("Conten t-type: image/png");

and run it from the form.

Thanks

[jeddiki]

Yep, That did the job !

I guess I must have deleted that variable somehow !

Thanks again for your help.

[Markus]

Glad you got it working.

Markus.