aspect-adjust

#!/usr/bin/perl

use strict;
use File::Basename;

my $basename = basename($0);

if (scalar @ARGV != 4) {
	print "usage: $basename <src-width> <src-height> <dest-width> <dest-height>\n";
	exit 1;
}

my $debug = 1;

my $src_w = $ARGV[0]; shift;
my $src_h = $ARGV[0]; shift;
my $dest_w = $ARGV[0]; shift;
my $dest_h = $ARGV[0]; shift;

my $new_w = 0;
my $new_h = 0;

if    (($src_w <= $dest_w) && ($src_h <= $dest_h))
{
	print "Source Smaller\n" if $debug;
	$new_w = $src_w;
	$new_h = $src_h;
}
elsif (($src_w <= $dest_w) && ($src_h >  $dest_h))
{
	print "Source Taller\n" if $debug;
	$new_w = $src_w * ($dest_h / $src_h);
	$new_h = $dest_h;
}
elsif (($src_w >  $dest_w) && ($src_h <= $dest_h))
{
	print "Source Wider\n" if $debug;
	$new_w = $dest_w;
	$new_h = $src_h * ($dest_w / $src_w);
}
elsif (($src_w >  $dest_w) && ($src_h >  $dest_h))
{
	print "Source Bigger\n" if $debug;
	my $w_aspect = $src_w / $dest_w;
	my $h_aspect = $src_h / $dest_h;

	if    ($h_aspect > $w_aspect)
	{
		print "Fit Height\n" if $debug;
		$new_h = $dest_h;
		$new_w = $src_w * ($dest_h / $src_h);
	}
	elsif ($w_aspect > $h_aspect)
	{
		print "Fit Width\n" if $debug;
		$new_w = $dest_w;
		$new_h = $src_h * ($dest_w / $src_w);
	}
	else
	{
		print "Fit Both\n" if $debug;
		$new_w = $dest_w;
		$new_h = $dest_h;
	}
}

my $src_aspect = $src_w / $src_h;
my $new_aspect = $new_w / $new_h;

if ($debug)
{
	printf "Change:   %d x %d -> %d x %d = %d x %d\n", $src_w, $src_h, $dest_w, $dest_h, $new_w, $new_h;
	printf "Aspect:   %f -> %f\n", $src_aspect, $new_aspect;
	printf "New Size: %d x %d\n", $new_w, $new_h;
	printf "\n";
}

printf "%dx%d\n", $new_w, $new_h;