#!/usr/bin/perl
use strict;
use warnings;
use Tk;
use Tk::Scrollbar;
use Tk::Text;

our ($textL, $textR, $yscroll, $xscrollleft, $xscrollright);

my $main          = Tk::MainWindow->new();
my $topframe      = $main->Frame()->pack();
my $topleftframe  = $topframe->Frame()->pack(-side => 'left');
my $toprightframe = $topframe->Frame()->pack(-side => 'left');
# Left again, because the yscroll is actually going on the right
# and putting right here would put yscroll in the middle

# Create left Text widget...
$textL= $topleftframe->Text(-wrap => 'none' )->pack(
-expand => 1,
-fill   => 'both',
);

# Create right Text Widget...
$textR = $toprightframe->Text(-width=>'20', -wrap => 'none' )->pack(
-expand => 1,
-fill   => 'both',
);

####################################
# scrollbars
####################################

# Setup vertical scroll bar for both text windows
$yscroll = $topframe->Scrollbar()->pack(
-fill => 'y',
-side => 'right',
);

# Setup two individual horizontal scroll bars for the text windows
$xscrollleft = $topleftframe->Scrollbar(
-orient=>'horizontal',
)->pack(
-fill   => 'x',
-side   => 'bottom',
-expand => 1,
);

$xscrollright = $toprightframe->Scrollbar(
-orient=>'horizontal',
)->pack(
-fill   => 'x',
-side   => 'bottom',
-expand => 1,
);

# Connect scrollbars to text widgets (and back again)...
$xscrollright
->configure( -command => [ \&xscroll_right, $xscrollright, $textR]);

$xscrollleft
->configure( -command => [ \&xscroll_left,  $xscrollleft,  $textL]);

$yscroll->configure( -command => [ \&scroll_both,   $yscroll,     [$textL,
$textR]]);

$textL  ->configure( -yscrollcommand => [ \&set_yscroll ]);
$textR  ->configure( -yscrollcommand => [ \&set_yscroll ]);
$textL  ->configure( -xscrollcommand => [ 'set', $xscrollleft]);
$textR  ->configure( -xscrollcommand => [ 'set', $xscrollright]);

# Load some data into them (FOR TESTING ONLY)
insert_data();

MainLoop();

# This handles updating yscroll, and making sure both the text
# boxes are sync'ed when one of them scrolls via the cursor keys
sub set_yscroll {
$yscroll->set(@_);

foreach my $w ($textL, $textR) {
$w->yviewMoveto($_[0]);
}
}

sub scroll_both {
my ($sb,$wigs,@args) = @_;
my $w;

foreach $w (@$wigs) {
$w->yview(@args);
}
}

sub xscroll_right {
my ($sb,$w,@args) = @_;

$w->xview(@args);
}

sub xscroll_left {
my ($sb,$w,@args) = @_;

$w->xview(@args);
}

sub insert_data {
my $testdata = <<'EOTESTDATA';
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39

Blah
Blah
Blah
Blah
Blah
Blah
Blah
Blah
Blah
Blah
Blah
Blah
Blah
Blah
Blah
Blah
Blah
Blah
Blah
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39
Blah
Blah
Blah
Blah
Blah
Blah
Blah
Blah
Blah
Blah
Blah
Blah
Blah
Blah
Blah
Blah
Blah
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39
EOTESTDATA

$textL->insert('end', $testdata);
$textR->insert('end', $testdata);
}