calc_size.pl

#!/usr/bin/perl -w
use strict;
use warnings;

use constant THRESHOLD => 50;
sub usage {
    print "Usage calc_size.pl <width> <height> <original width> <original height>\n";
    exit;
}

usage unless ( $#ARGV eq 3 );
my $width = $ARGV[0];
my $height = $ARGV[1];
my $orgWidth = $ARGV[2];
my $orgHeight = $ARGV[3];

my $newHeight;
my $newWidth;

$newWidth = $width;
$newHeight = ($newWidth / 768) * 1024;
if ( $newHeight > $height ) {
    $newHeight = $height;
    $newWidth = ($newHeight / 1024) * 768;
}

if ( $width - $newWidth > THRESHOLD || $height - $newHeight > THRESHOLD ) {
    $newWidth = $width;
    $newHeight = $height;
}

my $offsetX = ($orgWidth - $newWidth) / 2;
my $offsetY = 0;

printf("%dx%d+%d+%d\n", $newWidth, $newHeight, $offsetX, $offsetY);
1;