This next PPL program is a classic Tower of Hanoi game.
#!/usr/local/bin/perl -w
#
# Towers of Hanoi, Perl/Tk style. 2000/06/14, sol0@Lehigh.EDU
# Global package, subroutine and data declarations.
use Tk;
use Tk::Dialog;
use subs qw/do_hanoi fini hanoi init move_ring/;
use strict;
my $canvas; # the Hanoi playing field
my @colors; # 24 graduated ring colors
my $fly_y; # canvas Y-coord along which rings fly
my $max_rings; # be nice and keep @colors count-consistent
my $num_moves; # total ring moves
my %pole; # tracks pole X-coord and ring count
my %ring; # tracks ring canvas ID, width and pole
my $ring_base; # canvas Y-coord of base of ring pile
my $ring_spacing; # pixels between adjacent rings
my $stopped; # 1 IFF simulation is stopped
my $velocity; # pixel delta the rings move while flying
my $version = '1.0, 2000/06/14';
# Main.
my $mw = MainWindow->new(-use => $Plugin::brinfo{xwindow_id});
init;
MainLoop;
sub do_hanoi {
# Initialize for a new simulation.
my($n) = @_; # number of rings
return unless $stopped;
$stopped = 0; # start ...
$num_moves = 0; # ... new simulation
my $ring_height = 26;
$ring_spacing = 0.67 * $ring_height;
my $ring_width = 96 + $n * 12;
my $canvas_width = 3 * $ring_width + 4 * 12;
my $canvas_height = $ring_spacing * $n + $fly_y + 2 * $ring_height;
$ring_base = $canvas_height - 32;
# Remove all rings from the previous run and resize the canvas.
for (my $i = 0; $i < $max_rings; $i++) {
$canvas->delete($ring{$i, 'id'}) if defined $ring{$i, 'id'};
}
$canvas->configure(-width => $canvas_width, -height => $canvas_height);
# Initialize the poles: no rings, updated X coordinate.
for (my $i = 0; $i < 3; $i++) {
$pole{$i, 'x'} = ($i * $canvas_width / 3) + ($ring_width / 2) + 8;
$pole{$i, 'ring_count'} = 0;
}
# Initialize the rings: canvas ID, pole number, and width.
for (my $i = 0; $i < $n; $i++) {
my $color = '#' . $colors[$i % 24];
my $w = $ring_width - ($i * 12);
my $y = $ring_base - $i * $ring_spacing;
my $x = $pole{0, 'x'} - $w / 2;
my $r = $n - $i;
$ring{$r, 'id'} = $canvas->createOval(
$x, $y, $x + $w, $y + $ring_height,
-fill => $color, -outline => 'black', -width => 1,
);
$ring{$r, 'width'} = $w;
$ring{$r, 'pole'} = 0;
$pole{0, 'ring_count'}++;
}
# Start the simulation.
$mw->update;
hanoi $n, 0, 2, 1;
$stopped = 1;
} # end do_hanoi
sub hanoi {
# Recursively move rings until complete or stopped by the user.
my($n, $from, $to, $work) = @_;
return if $n <=0 or $stopped;
hanoi $n - 1, $from, $work, $to;
move_ring $n, $to unless $stopped;
hanoi $n - 1, $work, $to, $from;
}
sub init {
$fly_y = 32; # Y-coord rings use to fly between poles
$stopped = 1;
my $stop = sub {$stopped = 1};
my $about = $mw->Dialog(
-title => 'About tkhanoi',
-bitmap => 'info',
-default_button => 'OK',
-buttons => ['OK'],
-text => "tkhanoi version $version\n\n" .
"r - run simulation\n" .
"s - stop simulation\n" .
"q - quit program\n",
-wraplength => '6i',
);
# Menubar and menubuttons.
$mw->title("Towers of Hanoi");
$mw->configure(-menu => my $menubar = $mw->Menu);
my $file = $menubar->cascade(-label => 'File');
$file->command(-label => '~Quit', -command => \&fini,-accelerator => 'q');
my $game = $menubar->cascade(-label => 'Game');
$game->command(-label => '~Run', -command => sub {}, -accelerator => 'r');
$game->command(-label => '~Stop', -command => $stop, -accelerator => 's');
my $help = $menubar->cascade(-label => 'Help');
$help->command(-label => 'About', -command => sub {$about->Show});
my $info = $mw->Frame->pack;
# Number of rings scale.
my $rframe = $info->Frame(qw/-borderwidth 2 -relief raised/);
my $rlabel = $rframe->Label(-text => 'Number of Rings');
my $rscale = $rframe->Scale(
qw/-orient horizontal -from 1 -to 24 -length 200/,
);
$rscale->set(4);
$game->cget(-menu)->entryconfigure('Run',
-command => sub {do_hanoi $rscale->get},
);
$rframe->pack(qw/-side left/);
$rscale->pack(qw/-side right -expand 1 -fill x/);
$rlabel->pack(qw/-side left/);
# Ring velocity scale.
my $vframe = $info->Frame(qw/-borderwidth 2 -relief raised/);
my $vlabel = $vframe->Label(-text => 'Ring Velocity %');
my $vscale = $vframe->Scale(
qw/-orient horizontal -from 0 -to 100 -length 200/,
-command => sub {$velocity = shift},
);
$vscale->set(2);
$vframe->pack(qw/-side left/);
$vscale->pack(qw/-side right -expand 1 -fill x/);
$vlabel->pack(qw/-side left/);
# The simulation is played out on a canvas.
$canvas = $mw->Canvas(qw/-relief sunken/);
$canvas->pack(qw/-expand 1 -fill both/);
$canvas->createWindow(40, 10, -window =>
$canvas->Label(-textvariable => \$num_moves, -foreground => 'blue'),
);
# Each ring has a unique color, hopefully.
@colors = (qw/
ffff0000b000 ffff00006000 ffff40000000 ffff60000000
ffff80000000 ffffa0000000 ffffc0000000 ffffe0000000
ffffffff0000 d000ffff0000 b000ffff0000 9000ffff0000
6000ffff3000 0000ffff6000 0000ffff9000 0000ffffc000
0000ffffffff 0000e000ffff 0000c000ffff 0000a000ffff
00008000ffff 00006000ffff 00004000ffff 00000000ffff
/);
$max_rings = 24;
warn "Too few colors for $max_rings rings!" if $max_rings > $#colors + 1;
# Global key bindings that emulate menu commands.
$mw->bind('<KeyPress-r>' => sub {do_hanoi $rscale->get});
$mw->bind('<KeyPress-q>' => \&fini);
$mw->bind('<KeyPress-s>' => $stop);
} # end init
sub fini {
$mw->destroy;
}
sub move_ring {
# Move ring $n - its bounding box coordinates - to pole $to.
my($n, $to) = @_;
$num_moves++;
my $r = $ring{$n, 'id'};
my($x0, $y0, $x1, $y1) = map {int($_ + 0.5)} $canvas->coords($r);
# Float the ring upwards to the flying Y-coordinate, and decrement
# this pole's count.
my $delta;
while ($y0 > $fly_y) {
$delta = $y0 - $fly_y > $velocity ? $velocity : $y0 - $fly_y;
$canvas->coords($r, $x0, $y0 -= $delta, $x1, $y1 -= $delta);
$mw->update;
}
$pole{$ring{$n, 'pole'}, 'ring_count'}--;
# Determine the target X coordinate based on destination pole, and
# fly the ring over to the new pole. The first while moves rings
# left-to-right, the second while moves rings right-to-left.
my $x = $pole{$to, 'x'} - $ring{$n, 'width'} / 2;
while ($x0 < $x) {
$delta = $x - $x0 > $velocity ? $velocity : $x - $x0;
$canvas->coords($r, $x0 += $delta, $y0, $x1 += $delta, $y1);
$mw->update;
}
while ($x0 > $x) {
$delta = $x0 - $x > $velocity ? $velocity : $x0 - $x;
$canvas->coords($r, $x0 -= $delta, $y0, $x1 -= $delta, $y1);
$mw->update;
}
# Determine ring's target Y coordinate, based on the destination
# pole's ring count, and float the ring down.
my $y = $ring_base - $pole{$to, 'ring_count'} * $ring_spacing;
while ($y0 < $y) {
$delta = $y - $y0 > $velocity ? $velocity : $y - $y0;
$canvas->coords($r, $x0, $y0 += $delta, $x1, $y1 += $delta);
$mw->update;
}
$pole{$to, 'ring_count'}++;
$ring{$n, 'pole'} = $to;
} # end move_ring
