Image::Magick::Thumbnail::Fixed - Perl extension for creating fixed sized thumbnails without distortion.

  use Image::Magick::Thumbnail::Fixed;
  my $t = new Image::Magick::Thumbnail::Fixed;

  # Required parameters
  $t->thumbnail( input   => 'input.jpg',
                 output  => 'output.jpg',
                 width   => 96,
                 height  => 72 );

  # Required and optional parameters
  $t->thumbnail( input   => 'input.jpg',
                 output  => 'output.jpg',
                 width   => 96,
                 height  => 72,
                 density => '96x72',
                 gravity => 'center',
                 compose => 'over',
                 quality => '90',
                 bgcolor => 'white',
                 format  => 'jpg' );

package Image::Magick::Thumbnail::Fixed;

use 5.6.1;
use strict;
use warnings;
use Carp;

require Image::Magick;

our $VERSION = '0.04';

sub new {
  my $class = shift;  
  my $self = bless {}, $class;
}

sub debug {
  my $self = shift;
  $self->{debug} = shift;
}
 
sub thumbnail {
  my ($self, %args) = @_;
  
  my $im = new Image::Magick;
  
  # Required Parameters
  my $input   = $args{input};
  my $output  = $args{output};
  my $width   = $args{width};
  my $height  = $args{height};

  if( !$input ){
    carp "No input path specified";
    return undef;
  }
  
  if( !$output ){
    carp "No output path specified";
    return undef;
  }
  
  if( !$width ){
    carp "No width specified";
    return undef;
  }
  elsif( $width <= 0 ){
    carp "Invalid width";
    return undef;
  }
  
  if( !$height ){
    carp "No height specified";
    return undef;
  }elsif( $height <= 0 ){
    carp "Invalid height";
    return undef;
  }
  
  # Optional Parameters (passed to ImageMagick -- no local error checking)
  my $density = $args{density} || $width . "x" . $height;
  my $quality = $args{quality} || '70';
  my $bgcolor = $args{bgcolor} || 'white';
  my $format  = $args{format}  || 'jpg';
  my $compose = $args{compose} || 'over';
  my $gravity = $args{gravity} || 'center';
  

  if( $self->{debug} ){
    warn "Input   : $input\n";
    warn "Output  : $output\n";
    warn "ThumbWH : $width x $height\n";
    warn "Density : $density\n";
    warn "Quality : $quality\n";
    warn "BgColor : $bgcolor\n";
    warn "Format  : $format\n";
  }
  
  eval {

  	open(IMAGE,"<$input") or carp "Could not open $input: $!" and return undef;
  	my $err = $im->Read(file=>\*IMAGE);
  	die $err if $err;
	  close(IMAGE);

    # source image dimensions  
    my ($o_width, $o_height) = $im->Get('width','height');
  
  	warn "Source  : $o_width x $o_height\n" if $self->{debug};
   
    warn "Source image height <= 0 ($o_height)." and return undef if $o_height <= 0;
    warn "Source image width <= 0 ($o_width)." and return undef if $o_width  <= 0;
    
    # calculate image dimensions required to fit onto thumbnail
    my ($t_width, $t_height, $ratio);
    # wider than tall (seems to work...) needs testing
    if( $o_width > $o_height ){
      $ratio = $o_width / $o_height;
      $t_width = $width;    
      $t_height = $width / $ratio;
  
      # still won't fit, find the smallest size.
      while($t_height > $height){
        $t_height -= $ratio;
        $t_width -= 1;
      }
    }
    # taller than wide
    elsif( $o_height > $o_width ){
      $ratio = $o_height / $o_width;  
      $t_height = $height;
      $t_width = $height / $ratio;
  
      # still won't fit, find the smallest size.
      while($t_width > $width){
        $t_width -= $ratio;
        $t_height -= 1;
      }
    }
    # square (fixed suggested by Philip Munt phil@savvyshopper.net.au)
    elsif( $o_width == $o_height){
      $ratio = 1;
      $t_height = $width;
      $t_width  = $width;
       while (($t_width > $width) or ($t_height > $height)){
         $t_width -= 1;
         $t_height -= 1;
       }
    }

    warn "Ratio   : $ratio\n" if $self->{debug};
    warn "ThumbWH : $t_width x $t_height\n" if $self->{debug};      
  
    # Create thumbnail
    if( defined $im ){
      $im->Resize( width => $t_width, height => $t_height );
      $im->Set( quality => $quality );
      $im->Set( density => $density );
      
      my $thumb = new Image::Magick;
    
      $thumb->Set( size => $width . "x" . $height );
      $thumb->Set( quality => $quality );
      $thumb->Set( density => $density ); 
    
      $thumb->Read("gradient:$bgcolor-$bgcolor");
      
      $thumb->Composite( image   => $im, 
                         compose => $compose,
                         gravity => $gravity );
           
      $thumb->Write("$format:$output");
      
    }
  };
  if( $@ ){
    warn $@ and return undef;
  }
  return 1;
}

1;
__END__
# Below is stub documentation for your module. You'd better edit it!