Help with GD image creation

@CrazyMerlinJan 24.2006

Hey,

I wrote a script that outputs a filled rectangle with border, and inside is a random 8 char code that is machine unreadable, for a registration page.

I’m sure you know the type I’m talking about.

Instead of getting the png that I should be getting, I am getting a lot of line of garbled text.

I have the GD2 extension on, and I have specified: header(‘Content-type: image/png’) at the start of the document, but it still won’t draw.

Can someone tell me why? I’m sure it’s not the code, but something I’m not doing header or extension wise.

Here is the script:

[code=php] <? //create canvas size variables $size_x = 200; $size_y = 75; //create random 8 character code with 1 number in the middle $arrCode = array(‘a’,’b’,’c’,’d’,’e’,’f’,’g’,’h’,’i’,’j’,’k’,’l’,’m’,’n’,’o’,’p’,’q’,’r’,’s’,’t’,’u’,’v’,’w’,’x’,’y’,’z’); $arrNums = array(‘0′,’1′,’2′,’3′,’4′,’5′,’6′,’7′,’8′,’9’); for($i=0; $i < 7; $i++){ $t = mt_rand(0,26); $tcode .= $arrCode[$t]; }; //add a random number to the middle of the code $code = substr($tcode,0,3) . $arrNums[mt_rand(0,9)] . substr($tcode,4); //calculate space between characters $space_per_char = $size_x / (strlen($code) + 1); //create canvas $img = imagecreatetruecolor($size_x, $size_y); //allocate colors $background = imagecolorallocate($img, 255,255,255); $border = imagecolorallocate($img, 128,128,128); $colors[] = imagecolorallocate($img, 128,64,192); $colors[] = imagecolorallocate($img, 192,64,128); $colors[] = imagecolorallocate($img, 108,192,64); //fill background imagefilledrectangle($img, 1, 1, $size_x – 2, $size_y – 2, $background); imagerectangle($img, 0, 0, $size_x – 1, $size_y – 1, $border); //draw text for($i = 0; $i < strlen($code); $i++){ $color = $colors[$i % count($colors)]; imagettftext($img, 28 + mt_rand(0,8), -20 + mt_rand(0,40), ($i + 0.3) * $space_per_char, 50 + mt_rand(0,10), $color, ‘arial.ttf’, $code{$i}); }; //add distortion imageantialias($img, true); for($i = 0; $i < 1000; $i++){ $x1 = mt_rand(5, $size_x – 5); $y1 = mt_rand(5, $size_y – 5); $x2 = $x1 – 4 + mt_rand(0,8); $y2 = $y1 – 4 + mt_rand(0,8); imageline($img, $x1, $y1, $x2, $y2, $colors[mt_rand(0, count($colors) – 1)]); }; //output to page imagepng($img); ?> [/code]

also, I do all my scripts in raw and debug in my head and with alerts, can someone recommend a good IDE?

Thanks,
CM

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7 Comments(s) _↴

@CrazyMerlinauthorJan 24.2006 — #Ok, I got this working fine, but only when it was in a page of it's own.

I guess because it creates an image not a document, and won't allow anything else in the document.

My problem is, I can now display it is an iframe on the registration page, but how do I get the variable $code for verification?

I tried seeting a session variable once $code had been created, and then tried to get this variable, but I couldn't, and without a php debugger I'm not even sure if the session variable is being set.

thanks

@CrazyMerlinauthorJan 24.2006 — #Ok, I'm getting there slowly.

I now know the session variable is being set, and I can get it.

The problem is, the page that gets the session variable is completed before the page that writes it, so the value is always the previous value.

I could use a javascript call to setTimeout() to get the value, but is there a 'nicer' way to do it?

thanks

@bokehJan 24.2006 — #Your code is giving me a headache. If I echo $code at the end it returns a different code to the one displayed in the image. How are you going to read the image code if this is the case? It's no good randomising things to such a degree that the script can't access the code it is creating.

@CrazyMerlinauthorJan 24.2006 — #when I echo $code, from with thscript, juast after it's created it returns the correct value, the same as the image, but if I then assign it to a session variable, when I check the session variable it is different. After a few page refreshes you'll notice the the session variable has the value of the last displayed image, not the current one.

@bokehJan 24.2006 — #This works for me:

[code=php]<?php
 
 session_start();
 
 if(isset($_GET['i'])){
 
  // image creation section
  crazy_image();
 
 }elseif(isset($_POST['captcha'])){
 
  // validation section
  echo(captcha_validate())?'That was correct.<br>':'That was not correct.<br>';
  echo '<a href="http://'.$_SERVER['HTTP_HOST'].$_SERVER['PHP_SELF'].'">Try another?</a>';
  exit;
 
 }else{
 
  // form section
  echo
  '<img src="http://'.$_SERVER['HTTP_HOST'].$_SERVER['PHP_SELF'].'?i='.uniqid().'" alt=""><br>'."n".
  '<form action="http://'.$_SERVER['HTTP_HOST'].$_SERVER['PHP_SELF'].'" method="POST">'."n".
  '<input type="text" name="captcha" ><input type="submit" value="test it"></form>';
 
 }
 
 
 function crazy_image()
 {
 //create canvas size variables
 $size_x = 200;
 $size_y = 75;
 //create random 8 character code with 1 number in the middle
 $arrCode = array('a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x  ','y','z');
 $arrNums = array('0','1','2','3','4','5','6','7','8','9');
 for($i=0; $i < 7; $i++){
 $t = mt_rand(0,26);
 $tcode .= $arrCode[$t];
 };
 //add a random number to the middle of the code
 $code = substr($tcode,0,3) . $arrNums[mt_rand(0,9)] . substr($tcode,4);
 //calculate space between characters
 $space_per_char = $size_x / (strlen($code) + 1);
 //create canvas
 $img = imagecreatetruecolor($size_x, $size_y);
 //allocate colors
 $background = imagecolorallocate($img, 255,255,255);
 $border = imagecolorallocate($img, 128,128,128);
 $colors[] = imagecolorallocate($img, 128,64,192);
 $colors[] = imagecolorallocate($img, 192,64,128);
 $colors[] = imagecolorallocate($img, 108,192,64);
 //fill background
 imagefilledrectangle($img, 1, 1, $size_x - 2, $size_y - 2, $background);
 imagerectangle($img, 0, 0, $size_x - 1, $size_y - 1, $border);
 //draw text
 for($i = 0; $i < strlen($code); $i++){
 $color = $colors[$i % count($colors)];
 imagettftext($img, 28 + mt_rand(0,8), -20 + mt_rand(0,40), ($i + 0.3) * $space_per_char, 50 + mt_rand(0,10), $color, 'arial.ttf', $code{$i});
 };
 //add distortion
 imageantialias($img, true);
 for($i = 0; $i < 1000; $i++){
 $x1 = mt_rand(5, $size_x - 5);
 $y1 = mt_rand(5, $size_y - 5);
 $x2 = $x1 - 4 + mt_rand(0,8);
 $y2 = $y1 - 4 + mt_rand(0,8);
 imageline($img, $x1, $y1, $x2, $y2, $colors[mt_rand(0, count($colors) - 1)]);
 };
 //output to page
 header('Content-Type: image/png');
 imagepng($img);
 $_SESSION['captcha'] = str_replace(' ','',$code);
 }
 
 function captcha_validate()
 {
 return($_POST['captcha'] == $_SESSION['captcha']);
 }
 
 ?>[/code]

@CrazyMerlinauthorJan 24.2006 — #Thank you bokeh, I was pulling my hair out then.

@bokehJan 24.2006 — #Thank you bokeh, I was pulling my hair out then.[/QUOTE]You're welcome! Personally I find your image a bit hard to read. And the randomization a bit over complex. [URL=http://bokehman.com/captcha_verification]Here's one I made with audio backup[/URL]. And the following one is at the other end of the complexity scale.

[code=php]<?php
 
 function captcha_image()
 {
 $_SESSION['captcha'] = substr(uniqid(), 0, 8);
 $image = imagecreate(80, 20);
 $background_colour = imagecolorallocate($image, 255,255,255);
 $text_shadow = imagecolorallocate($image, 127,127,127);
 $text_colour = imagecolorallocate($image, 0,0,0);
 imagestring($image, 5, 1, 1, $_SESSION['captcha'], $text_shadow);
 imagestring($image, 5, 0, 0, $_SESSION['captcha'], $text_colour);
 header ('Content-type: image/png');
 imagepng($image, null, 100);
 imagedestroy($image); 
 exit;
 }
 
 ?>[/code]

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