Help with a short script:

Jackanape

THis script is SUPPOSED to genereate numbers in png format for verification on a form, but whenever I try to use it I get:

In fact, when I load the file into my browser, I get:

The image “http://xxxxxxxxxxxx.com/forum/rand.php” cannot be displayed, because it contains errors.

Well, here's the rand.php file, too:

<?php
header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");

header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");

header("Cache-Control: no-store, no-cache, must-revalidate");
header("Cache-Control: post-check=0, pre-check=0", false);

header("Pragma: no-cache"); 
header("Content-Type: image/png");
session_start();
$im = ImageCreate(80, 25);

$white = ImageColorAllocate($im, 255, 255, 255);
$black = ImageColorAllocate($im, 0, 0, 0);

$string = md5(rand(0,9999));

$_SESSION["new_string"] = substr($string, 17, 5);
ImageFill($im, 0, 0, $black);

ImageString($im, 4, 15, 5, $_SESSION["new_string"], $white);

ImagePNG($im);
ImageDestroy($im);
?>

Any and all help is appreciated!!

harmor

What happens when you go to "rand.php" directly?

Jackanape

I get this:

The image “http://xxxxxxxxxxxx.com/forum/rand.php” cannot be displayed, because it contains errors.

harmor

I thought you were doing something else.

I don't know anything about image creation offhand so I can't say "do this here" and "put that there".
My guess it has something to do with "$im = ImageCreate(80, 25);"

Read This
http://www.phpnoise.com/tutorials/1/2

Rodney_H_

The script, "rand.php", as you have it posted, runs on my computer without any error messages. Could it be a problem with your GD library? Has your version of PHP been compiled correctly with it??

harmor

Rodney H. wrote:
The script, as you have it posted, runs on my computer. Could it be a problem with your GD library? Has your version of PHP been compiled correctly with it??

The problem is that "Jack" didn't put an image to output it to in
ImagePNG($im);

This should be something like
ImagePNG($im, "image.png");

Rodney_H_

So certain are you, harmor? http://us3.php.net/ImagePNG

harmor

99% certain.

If he wanted to alter an image then he would use "imagecreatefrompng" but he wants to make a random image for verification so according to the tutorial I could possibly be right.

Rodney_H_

I don't know, harmor. I guess it depends HOW he calls the image into his script/page.

If he names the image, for example 'captcha.png', then he must use that name in his page, like this: <img src="captcha.png" />

Otherwise, I was under the impression that he was naming/using the image source as the .php file like this: <img src="rand.php" />

.... c'est la vie...

/* off topic

Also, I apologize if I put you on the defensive.... looooong day...

Weedpacket

Juding from the error message "...because it contains errors" - that sounds like a browser-generated error message thrown up if it is asked to display an invalid image as itself (rather than in a page) - what you'd see if you tried entering the image's URL directly, rather than putting it in an HTML <img> tag.

Since it's not getting what it should (an image), one step in debugging I'd do would be to either take the Content-Type out and try rendering it as HTML (probably the simplest thing to try), or saving the "image" and looking at it in a text or hex editor; basically, see what it is getting.