Dynamically Generated Text Images

I found a variety of links on using the GD image library with PHP to create dynamic images, such as this one from Codewalkers to create a dynamic graphical clock, and this snippet at MiniFonts to use their fonts on the Web.

I put together a small file, image.php that would take some of the URL parameters and generate an image with using my rather hard coded preferences.

This section sets up the PHP code to return a PNG mime type:

<?php
// Set the content-type
header("Content-type: image/png");

This clever bit eliminates GD path search functions, as I put the font file in the same directory as the image.php file:

// Set the environment variable for GD
putenv('GDFONTPATH=' . realpath('.'));

Some crude error checking:

if (isset($_GET['text'])) {  
   $text = ($_GET['text']);  

   $px = (int)($_GET['px']);
   if ($px == 0) {
      $px = 12;
   }

And create the image:

   // Name the font to be used (note the lack of the .ttf extension)
   $font = 'robblock';

   // Get the image size
   $size = imagettfbbox($px,0,$font,$text);

   // Create the image
   $im = imagecreate(abs($size[4]-$size[0])+2,$size[1]+abs($size[5])+2);

   // Create some colors
   $white = imagecolorallocate($im, 255, 255, 255);
   $grey = imagecolorallocate($im, 128, 128, 128);
   $black = imagecolorallocate($im, 0, 0, 0);
   $orange = imagecolorallocate($im, 255, 102, 0);

   // Add some shadow to the text
   imagettftext($im, $px, 0, 1, abs($size[5])+1, $black, $font, $text);

   // Add the text
   imagettftext($im, $px, 0, 0, abs($size[5]), $orange, $font, $text);

   // Using imagepng() results in clearer text compared with imagejpeg()
   imagepng($im);

And free up memory so we don't run out:

   imagedestroy($im);
}
?> 

Just drop this file and the selected font file into the same directory, set up the permissions appropriately and call it like so:

http://path/to/my/file/image.php?text=Testing 1.2.3.&px=12

Which returns the following image:

Now because the Serendipity blog software uses smarty templating, this can easily be used to do what I wanted, namely, to render my entry titles in my (admittedly messy) printing. I just changes the H4 header line in the entries.tpl file to:

      <h4><a href="{$entry.link}"><img 
	src="http://path/to/my/file/image.php?text={$entry.title}&px=12" 
	alt="{$entry.title}" border="0"></a></h4>

This renders the text as a pretty graphic with drop shadows, as well as filling in the ALT tag of the image for those who can't use images.