Creating thumbnails on the fly under FastCGI

A while ago I wrote about the problems I was having with trying to get Image::Magick to create thumbnails on the fly whilst running under FastCGI. Well, I was right then that the problem lay in the fact that FCGI ties STDOUT whilst Image::Magick also wants to access STDOUT to write to. I spent a couple more hours trying to figure out how to untie STDOUT, do the Image::Magick->Write to STDOUT then re-attach it to FCGI. No luck. The FCGI->Detach method didn't do it. Under hood was too complex for me to understand.

I retreated and looked at GD again. Similar problems, as well as a messier interface. Then I had a gander around seach.cpan.org and picked up on Imager. Thanks to the handy rating stars on the search pages it looked promising. And really, it is a breath of fresh air: well documented, developer-friendly interface, myriad options and ways to play with images (including the scale() method which automatically scales in proportion). And, crucially, you can write() your images to a scalar variable, which means you can then print that scalar and FCGI will scoop it up and print it out like any other print statement.

Job done: I can now make thumbnail images on the fly and send them back to the browser under FastCGI by dropping Image::Magick for the new and very impressive Imager.

#!/usr/bin/perl

use Imager;
use FCGI;
use strict;

$| = 1;

my $dir = qw(../images/);

my $r = FCGI::Request();

while($r->Accept() >= 0) {
  opendir(DIR, $dir);
  my @files  = grep { ! /^\./ } readdir DIR;
  my $file   = $files[int(rand($#files+1))];

  my $image = Imager->new;
  $image->read(file=>$dir.$file) or die $image->errstr;
  my $thumb = $image->scale(xpixels=>80) or die $image->errstr;
  my $data;
  $thumb->write(type => 'png', data => \$data) or die $image->errstr;

  print "Content-type: image/png\n\n";
  binmode STDOUT;
  print $data;
}