use Tk;
use strict;
use warnings;

my ($wf_canvas, $wid);

my $mw = MainWindow->new;
$mw->geometry("600x300+10+10");

my $menubar_frame = $mw->Frame(-relief => 'ridge', -borderwidth => 2)
  ->pack(-side => 'top', -anchor => 'n', -fill => 'x');

my $plot1_button = $menubar_frame->Button(
      -command => [\&plotwave1],
      -text => 'Plot short')
      ->pack(-side => 'left');

my $plot2_button = $menubar_frame->Button(
      -command => [\&plotwave2],
      -text => 'Plot long')
      ->pack(-side => 'left');

my $exit_button = $menubar_frame->Button(
      -command => sub {$mw->destroy},
      -text => 'Exit')
      ->pack(-side => 'left');

MainLoop;

exit;

sub wfplot_canvas() {
  if (! Exists($wf_canvas)) {
    $wf_canvas = $mw->Canvas(-background => 'white');
    $wf_canvas->pack(-expand => 1, -fill => 'both', -side => 'left');
  }
}

sub plotwave($) {
  my $len = shift;
  my $xscale = $mw->width() / $len;
  my @xy = ();
  my $i;
  foreach $i (0 .. ($len - 1)) {
    push @xy, $i * $xscale, 100 - sin(0.00001 * $i) * 100;
  }
  $wid = $wf_canvas->createLine(@xy, -fill => 'black', -joinstyle => 'bevel');
  my @bbox = $wf_canvas->bbox('all');
  $wf_canvas->configure(-height => ($bbox[3] - $bbox[1]),
    -width => ($bbox[2] - $bbox[0]));
  return;
}

sub plotwave1() {
  wfplot_canvas() if ! Exists($wf_canvas);
  $wf_canvas->delete($wid) if $wid;
  plotwave(1048572);
}

sub plotwave2() {
  wfplot_canvas() if ! Exists($wf_canvas);
  $wf_canvas->delete($wid) if $wid;
  plotwave(1048573);
}