#!/usr/bin/perl -w

# Name     : Perl/Tk Text Viewer
# Author   : Terrence Ma
# Email    : terrence@terrence.com
# Web      : http://www.terrence.com
# Date     : 09/01/2001
# License  : GNU GPL - http://www.gnu.org/copyleft/gpl.html
# Warranty : No Warranty

# use lib
use 5;
use strict;
use Fcntl qw(:DEFAULT :flock);
use Tk;

# init variables
my($top, $textview, $scrollview);

# procedure get file
sub getfile {
  my($filename, $filecontents);
  $filename = shift(@_);

  open(FILEHANDLE, "< $filename") || die "Can't read $filename: $!";
  flock(FILEHANDLE, LOCK_SH) || die "Can't lock filename: $!";

# read file in one pass
# see Advanced Perl Programming p.42
  {
    local $/ = undef;               # Saves previous value of $/
                                    # substitutes it with undef
    $filecontents = <FILEHANDLE>;   # Slurp all of FILEHANDLE
  }

  $textview->delete("1.0", "end");
  $textview->insert("end", $filecontents);
  close(FILEHANDLE);
}

# set top window
$top = MainWindow->new();

# set widgets
# configure $textview(yscrollcommand) at the end to avoid lookahead error
$textview   = $top->Text(bg => "white");
$scrollview = $top->Scrollbar(command => ["yview", $textview]);

# check argument, get filename
if (($#ARGV == 0) && (-e $ARGV[0])) {
  $top->title("Perl/Tk Text Viewer");
  $textview->pack(side => "left");
  $scrollview->pack(side => "right", fill => "y");
  $textview->configure(yscrollcommand => ["set", $scrollview]);
  getfile($ARGV[0]);
  MainLoop();

} else {
  print("Usage: viewer.pl filename\n");
}