my $gui_aspect=$gui->width/$gui->height;
my $img_aspect=$img->width/$img->heigth;
my $diff_aspect=$gui_aspect-$img_aspect;

my $scale=1;

if($diff_aspect < 0)
{ $scale=$gui->height/$img->height; }
else
{ $scale=$gui->width/$img->width; }

$img->scale($scale);