package Gtk2::GoBoard;

=head1 NAME

Gtk2::GoBoard - high quality goban widget with sound

=head1 SYNOPSIS

   use Games::Go::SimpleBoard;

   my $goboard = newe Games::Go::SimpleBoard;

   use Gtk2::GoBoard;

   my $gtkboard = new Gtk2::GoBoard size => 19;

   # update board, makes a copy
   $gtkboard->set_board ($goboard);

   # advanced: enable stone curser for black player, showing
   # only valid moves
   $gtkboard->set (cursor => sub {
      my ($mark, $x, $y) = @_;

      $mark |= MARK_GRAYED | MARK_B
         if $goboard->is_valid_move (COLOUR_WHITE,
                                     $x, $y,
                                     $ruleset == RULESET_NEW_ZEALAND);

      $mark
   });

   # button-release and -press events pass board coordinates
   $gtkboard->signal_connect (button_release => sub {
      my ($button, $x, $y) = @_;

      ...
   });

=head1 DESCRIPTION

This is the very first "true" Gtk2 widget written in Perl.

The C<Gtk2::GoBoard> class works like any other widget, see the SYNOPSIS
for short examples of the available methods, and the L<App::IGS> and
L<KGS> modules for usage examples.

Please supply a more descriptive description :)

=head2 SOUND SUPPORT

In addition to a graphical board widget, this module has some rudimentary
support for sounds.

Playing sounds required the L<Audio::Play> module. If it isn't installed,
sounds will silently not being played. The module intentionally doesn't
depend on L<Audio::Play> as it isn't actively maintained anymore and fails
to install cleanly.

Note that L<Audio::Play> is broken on 64-bit platforms, which the author
knows about for half a decade now, but apparently can't be bothered to
fix. The symptoms are that it cannot load the soundfile and will silently
result in - silence.

=over 4

=cut

our $VERSION = '1.02';

no warnings;
use strict;

use Scalar::Util;
use POSIX qw(ceil);
use Carp ();
use Gtk2;

use Games::Go::SimpleBoard;

use Glib::Object::Subclass
   Gtk2::AspectFrame::,
   properties => [
      Glib::ParamSpec->IV (
         "size",
         "Board Size",
         "The Go Board size, 2..38",
         2, 38, 19,
         [qw(construct-only writable readable)],
      ),
      Glib::ParamSpec->scalar (
         "cursor",
         "cursor callback",
         "The callback that modifies the cursor mask",
         [qw(writable readable)],
      ),
   ],
   signals => {
      "button-press" => {
         flags       => [qw/run-first/],
         return_type => undef, # void return
         param_types => [Glib::Int::, Glib::Int::, Glib::Int::], # instance and data are automatic
      },
      "button-release" => {
         flags       => [qw/run-first/],
         return_type => undef, # void return
         param_types => [Glib::Int::, Glib::Int::, Glib::Int::], # instance and data are automatic
      },
      destroy        => sub {
         $_[0]->signal_chain_from_overridden;
         %{$_[0]} = ();
      },
   };

# some internal constants

sub TRAD_WIDTH  (){ 42.42 } # traditional board width
sub TRAD_HEIGHT (){ 45.45 } # traditional board height
sub TRAD_RATIO  (){ TRAD_WIDTH / TRAD_HEIGHT } # traditional (nihon-kiin) horizontal spacing
sub TRAD_SIZE_B (){  2.18 } # traditional black stone size
sub TRAD_SIZE_W (){  2.12 } # traditional white stone size

sub SHADOW	(){  0.06 } # 0.09 probably max.

# find a data file using @INC
sub findfile {
   my @files = @_;
   file:
   for (@files) {
      for my $prefix (@INC) {
         if (-f "$prefix/Gtk2/GoBoard/data/$_") {
            $_ = "$prefix/Gtk2/GoBoard/data/$_";
            next file;
         }
      }
      die "$_: file not found in \@INC\n";
   }
   wantarray ? @files : $files[0];
}

sub load_image {
   my $path = findfile $_[0];

   new_from_file Gtk2::Gdk::Pixbuf $path
      or die "$path: $!";
}

our ($board_img, @black_img, @white_img, $shadow_img,
     @triangle_img, @square_img, @circle_img, @cross_img);

sub load_images {
   $board_img    =       load_image "woodgrain-01.jpg";
   @black_img    =       load_image "b-01.png";
   @white_img    = map +(load_image "w-0$_.png"), 1 .. 5;
   $shadow_img   =       load_image "shadow.png"; # also used to fake hoshi points
   @triangle_img = map +(load_image "triangle-$_.png"), qw(b w);
   @square_img   = map +(load_image "square-$_.png"  ), qw(b w);
   @circle_img   = map +(load_image "circle-$_.png"  ), qw(b w);
   @cross_img    = map +(load_image "cross-$_.png"   ), qw(b w);
}

sub INIT_INSTANCE {
   my $self = shift;

   @black_img
      or load_images;

   $self->double_buffered (0);
   $self->set (border_width => 0, shadow_type => 'none',
               obey_child => 0, ratio => TRAD_RATIO);

   $self->add ($self->{canvas} = new Gtk2::DrawingArea);

   $self->{canvas}->signal_connect (motion_notify_event  => sub { $self->motion });
   $self->{canvas}->signal_connect (leave_notify_event   => sub { $self->cursor (0); delete $self->{cursorpos} });
   $self->{canvas}->signal_connect (button_press_event   => sub { $self->button ("press", $_[1]) });
   $self->{canvas}->signal_connect (button_release_event => sub { $self->button ("release", $_[1]) });

   $self->{canvas}->signal_connect_after (configure_event => sub { $self->configure_event ($_[1]) });
   $self->{canvas}->signal_connect_after (realize => sub {
      my $window = $_[0]->window;
      my $color = new Gtk2::Gdk::Color 0xdfdf, 0xb2b2, 0x5d5d;
      $window->get_colormap->alloc_color ($color, 0, 1);
      $window->set_background ($color);
   });

   $self->{canvas}->set_events ([
      @{ $self->{canvas}->get_events },
     'leave-notify-mask',
     'button-press-mask',
     'button-release-mask',
     'pointer-motion-mask',
     'pointer-motion-hint-mask'
   ]);
}

sub SET_PROPERTY {
   my ($self, $pspec, $newval) = @_;

   $pspec = $pspec->get_name;

   $self->cursor (0) if $pspec eq "cursor";
   $self->{$pspec} = $newval;
   $self->cursor (1) if $pspec eq "cursor";
}

sub configure_event {
   my ($self, $event) = @_;

   return if $self->{idle};

   return unless $self->{canvas}->allocation->width  != $self->{width}
              || $self->{canvas}->allocation->height != $self->{height};

   my $drawable = $self->{window} = $self->{canvas}->window;
   $drawable->set_back_pixmap (undef, 0);

   delete $self->{stack};

   # remove Glib::Source $self->{idle};
   $self->{idle} ||= add Glib::Idle sub {
      $self->{width}  = $self->{canvas}->allocation->width;
      $self->{height} = $self->{canvas}->allocation->height;
      $self->draw_background;

      $self->draw_board ({ board => delete $self->{board}, label => delete $self->{label} }, 0) if $self->{board};
      $self->{window}->clear_area (0, 0, $self->{width}, $self->{height});

      delete $self->{idle};

      0;
   };

   1;
}

=item $board->set_board ($games_go_simpleboard)

Sets the new board position to display from the current position stored in
the L<Games::Go::SimpleBoard> object.

=cut

sub set_board {
   my ($self, $board) = @_;

   $self->cursor (0);
   $self->draw_board ($board, 1);
   $self->cursor (1);
}

sub new_pixbuf {
   my ($w, $h, $alpha, $fill) = @_;

   my $pixbuf = new Gtk2::Gdk::Pixbuf 'rgb', $alpha, 8, $w, $h;
   $pixbuf->fill ($fill) if defined $fill;

   $pixbuf;
}

sub scale_pixbuf {
   my ($src, $w, $h, $mode, $alpha) = @_;

   my $dst = new_pixbuf $w, $h, $alpha;

   $src->scale(
      $dst, 0, 0, $w, $h, 0, 0,
      $w / $src->get_width, $h / $src->get_height,
      $mode,
   );

   $dst;
}

sub pixbuf_rect {
   my ($pb, $colour, $x1, $y1, $x2, $y2, $alpha) = @_;

   # we fake lines by... a horrible method :/
   my $colour_pb = new_pixbuf 1, 1, 0, $colour;
   $colour_pb->composite ($pb, $x1, $y1, $x2 - $x1 + 1, $y2 - $y1 + 1, $x1, $y1, $x2 + 1, $y2 + 1,
                          'nearest', $alpha);
}

sub center_text {
   my ($self, $drawable, $colour, $x, $y, $size, $text) = @_;

   # could be optimized by caching quite a bit

   my $context = $self->get_pango_context;
   my $font = $context->get_font_description;
   $font->set_size ($size * Gtk2::Pango->scale);

   my $layout = new Gtk2::Pango::Layout $context;
   $layout->set_text ($text);
   my ($w, $h) = $layout->get_pixel_size;

   my $gc = new Gtk2::Gdk::GC $drawable;

   my $r = (($colour >> 24) & 255) * (65535 / 255);
   my $g = (($colour >> 16) & 255) * (65535 / 255);
   my $b = (($colour >>  8) & 255) * (65535 / 255);

   $gc->set_rgb_fg_color (new Gtk2::Gdk::Color $r, $g, $b);
   
   $drawable->draw_layout ($gc, $x - $w*0.5, $y - $h*0.5, $layout);
}

# draw an empty board and attach the bg pixmap
sub draw_background {
   my ($self) = @_;
   my $canvas = $self->{canvas};

   my $size = $self->{size};

   my $w = $self->{width};
   my $h = $self->{height};

   delete $self->{backgroundpm};
   delete $self->{backgroundpb};

   my $pixmap = new Gtk2::Gdk::Pixmap $self->window, $w, $h, -1;

   my $gridcolour  = 0x44444400; # black is traditional, but only with overlapping stones
   my $labelcolour = 0x88444400;

   my $borderw = int $w / ($size + 1) * 0.5;
   my $borderh = $borderw;
   my $w2      = $w - $borderw * 2;
   my $h2      = $h - $borderh * 2;
   my $edge    = ceil $w2 / ($size + 1);
   my $ofs     = $edge * 0.5;

   # we need a certain minimum size, and just fudge some formula here
   return if $w < $size * 5 + 2 + $borderw
          || $h < $size * 6 + 2 + $borderh;

   my @kx = map int ($w2 * $_ / ($size+1) + $borderw + 0.5), 0 .. $size; $self->{kx} = \@kx;
   my @ky = map int ($h2 * $_ / ($size+1) + $borderh + 0.5), 0 .. $size; $self->{ky} = \@ky;

   my $pixbuf;

   my ($bw, $bh) = ($board_img->get_width, $board_img->get_height);

   if ($w < $bw && $h < $bh) {
      $pixbuf = new_pixbuf $w, $h, 0;
      $board_img->copy_area (0, 0, $w, $h, $pixbuf, 0, 0);
   } else {
      $pixbuf = scale_pixbuf $board_img, $w, $h, 'bilinear', 0; # nearest for extra speed
   }

   my $linew = int $w / 40 / $size;

   # ornamental border... we have time to waste :/
   pixbuf_rect $pixbuf, 0xffcc7700, 0, 0,           $w-1, $linew, 255;
   pixbuf_rect $pixbuf, 0xffcc7700, 0, 0,           $linew, $h-1, 255;
   pixbuf_rect $pixbuf, 0xffcc7700, $w-$linew-1, 0, $w-1, $h-1,   255;
   pixbuf_rect $pixbuf, 0xffcc7700, 0, $h-$linew-1, $w-1, $h-1,   255;

   for my $i (1 .. $size) {
      pixbuf_rect $pixbuf, $gridcolour, $kx[$i] - $linew, $ky[1] - $linew, $kx[$i] + $linew, $ky[$size] + $linew, 255;
      pixbuf_rect $pixbuf, $gridcolour, $kx[1] - $linew, $ky[$i] - $linew, $kx[$size] + $linew, $ky[$i] + $linew, 255;
   }

   # hoshi points
   my $hoshi = sub {
      my ($x, $y) = @_;
      my $hs = 1 | int $edge / 4;
      $hs = 5 if $hs < 5;
      $x = $kx[$x] - $hs / 2; $y = $ky[$y] - $hs / 2;

      # we use the shadow mask... not perfect, but I want to finish this
      $shadow_img->composite ($pixbuf,
            $x, $y, ($hs + 1) x2, $x, $y,
            $hs / $shadow_img->get_width, $hs / $shadow_img->get_height,
            'bilinear', 255);
   };

   if ($size > 6) {
      my $h1 = $size < 10 ? 3 : 4; # corner / edge offset
      $hoshi->($h1, $h1);
      $hoshi->($size - $h1 + 1, $h1);
      $hoshi->($h1, $size - $h1 + 1);
      $hoshi->($size - $h1 + 1, $size - $h1 + 1);

      if ($size % 2) { # on odd boards, also the remaining 5
         my $h2 = ($size + 1) / 2;
         if ($size > 10) {
            $hoshi->($h1, $h2);
            $hoshi->($size - $h1 + 1, $h2);
            $hoshi->($h2, $size - $h1 + 1);
            $hoshi->($h2, $h1);
         }
         # the tengen
         $hoshi->($h2, $h2);
      }
   }

   # now we have a board sans text
   $pixmap->draw_pixbuf ($self->style->white_gc,
         $pixbuf,
         0, 0, 0, 0, $w, $h,
         "normal", 0, 0);

   # now draw the labels
   for my $i (1 .. $size) {
      # 38 max, but we allow a bit more
      my $label = (qw(- A  B  C  D  E  F  G  H  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z
                        AA BB CC DD EE FF GG HH JJ KK LL MM NN OO PP QQ RR SS TT UU VV WW XX YY ZZ))[$i];

      $self->center_text ($pixmap, $labelcolour, $kx[$i], $borderh,       $ofs * 0.7, $label);
      $self->center_text ($pixmap, $labelcolour, $kx[$i], $h2 + $borderh, $ofs * 0.7, $label);
      $self->center_text ($pixmap, $labelcolour, $borderw, $ky[$i],       $ofs * 0.7, $size - $i + 1);
      $self->center_text ($pixmap, $labelcolour, $w2 + $borderw, $ky[$i], $ofs * 0.7, $size - $i + 1);
   }

   $self->{window}->set_back_pixmap ($pixmap, 0);

   $self->{backgroundpm} = $pixmap;
   $self->{backgroundpb} = $pixbuf;

   $edge = int ($edge * TRAD_SIZE_B / TRAD_SIZE_W);
   $ofs  = int ($edge * 0.5);

   {
      # shared vars for the stone drawing function
      my $shadow = $edge * SHADOW;
      my $pb;
      my @area;
      my @areai;
      my %stack;

      my $put_stack = sub {
         my ($x, $y, $dx, $dy, $ox, $oy) = @_;

         my $mark = $self->{board}[$x-1][$y-1];

         if ($mark & ~MARK_LABEL) {
            my $stack = $stack{$mark} ||= $self->draw_stack ($mark, $edge);

            $stack->[($x ^ $y) % @$stack]
                  ->composite ($pb,
                               $ox, $oy,
                               $areai[2] + $dx - $ox, $areai[3] + $dy - $oy,
                               $dx + $ox, $dy + $oy,
                               1, 1, 'nearest', 255);
         }
      };

      $self->{draw_stone} = sub {
         my ($x, $y) = @_;

         @area  = ($kx[$x] - $ofs, $ky[$y] - $ofs,
                      $edge + $shadow, $edge + $shadow);
         @areai = map +(ceil $_), @area; # area, integer
         
         $pb = new_pixbuf @areai[2,3];
         $self->{backgroundpb}->copy_area (@areai, $pb, 0, 0);

         $put_stack->($x-1, $y, $kx[$x-1] - $kx[$x], 0, 0, 0) if $x > 1;
         $put_stack->($x, $y-1, 0, $ky[$y-1] - $ky[$y], 0, 0) if $y > 1;
         $put_stack->($x , $y , 0, 0);
         $put_stack->($x+1, $y, 0, 0, $kx[$x+1] - $kx[$x], 0) if $x < $size;
         $put_stack->($x, $y+1, 0, 0, 0, $ky[$y+1] - $ky[$y]) if $y < $size;

         # speed none, normal, max
         $self->{backgroundpm}->draw_pixbuf ($self->style->black_gc, $pb,
                                  0, 0, @areai, 'max', 0, 0);

         # labels are handled here because they are quite rare
         # (and we can't draw text into pixbufs easily)
         my $mark = $self->{board}[$x-1][$y-1];

         if ($mark & MARK_LABEL) {
            my $white = $mark & MARK_W ? 0 : 0xffffff00;

            $self->center_text ($self->{backgroundpm}, 0,
                                $areai[0] + $ofs * 1.1, $areai[1] + $ofs * 1.1,
                                $ofs * 0.7, $self->{label}[$x-1][$y-1])
               if $white;

            $self->center_text ($self->{backgroundpm}, $white,
                                $areai[0] + $ofs, $areai[1] + $ofs,
                                $ofs * 0.7, $self->{label}[$x-1][$y-1]);
         }

         undef $pb;
         
         [@areai];
      };
   }
}

# create a stack of stones, possibly in various versions
sub draw_stack {
   my ($self, $mark, $size) = @_;

   my @stack;
   my $csize = ceil $size;
   my $shadow = $size * SHADOW;

   for my $stone ($mark & MARK_W ? @white_img : @black_img) {
      my $base = new_pixbuf +(ceil $csize + $shadow) x2, 1, 0x00000000;

      # zeroeth the shadow
      if (~$mark & MARK_GRAYED and $mark & (MARK_B | MARK_W)) {
         $shadow_img->composite (
            $base,  ($shadow) x2, $csize, $csize, ($shadow) x2,
            $size / $shadow_img->get_width, $size / $shadow_img->get_height,
            'bilinear', 128
         );
      }

      for ([MARK_B, $mark & MARK_GRAYED ? 106 : 255, 1],
           [MARK_W, $mark & MARK_GRAYED ? 190 : 255, TRAD_SIZE_W / TRAD_SIZE_B]) {
         my ($mask, $alpha, $scale) = @$_;
         if ($mark & $mask) {
            $stone->composite (
               $base, 0, 0, $csize, $csize, ($size * (1 - $scale) * 0.5) x2,
               $size * $scale / $stone->get_width, $size * $scale / $stone->get_height,
               'bilinear', $alpha
            );
         }
      }

      # then the small stones (always using the first image)
      for ([MARK_SMALL_B, $mark & MARK_SMALL_GRAYED ? 106 : 255, $black_img[0]],
           [MARK_SMALL_W, $mark & MARK_SMALL_GRAYED ? 190 : 255, $white_img[0]]) {
         my ($mask, $alpha, $img) = @$_;
         if ($mark & $mask) {
            $img->composite (
               $base, ($size / 4) x2, (ceil $size / 2 + 1) x2, ($size / 4) x2,
               $size / $img->get_width / 2, $size / $img->get_height / 2,
               'bilinear', $alpha
            );
         }
      }

      # and finally any markers
      my $dark_bg = ! ! ($mark & MARK_B);

      for ([MARK_CIRCLE,   $circle_img  [$dark_bg]],
           [MARK_TRIANGLE, $triangle_img[$dark_bg]],
           [MARK_CROSS,    $cross_img   [$dark_bg]],
           [MARK_SQUARE,   $square_img  [$dark_bg]],
           [MARK_KO,       $square_img  [$dark_bg]]) {
        my ($mask, $img) = @$_;
        if ($mark & $mask) {
           $img->composite (
              $base, 0, 0, $csize, $csize, 0, 0,
              $size / $img->get_width, $size / $img->get_height,
              'bilinear', $dark_bg ? 176 : 190
           );
        }
      }

      push @stack, $base;
   }

   \@stack
}

sub draw_board {
   my ($self, $new, $dopaint) = @_;

   my $newboard = $new->{board};
   my $newlabel = $new->{label};

   if ($self->{backgroundpb}) {
      my $draw_stone = $self->{draw_stone};

      my $oldboard = $self->{board} ||= [];
      my $oldlabel = $self->{label} ||= [];

      my @areas;

      my $size1 = $self->{size} - 1;

      for my $x (0 .. $size1) {
         my $old = $oldboard->[$x] ||= [];
         my $new = $newboard->[$x];

         for my $y (0 .. $size1) {
            next if $old->[$y] == $new->[$y];

            $old     ->    [$y] = $new     ->    [$y];
            $oldlabel->[$x][$y] = $newlabel->[$x][$y];

            push @areas, $draw_stone->($x+1, $y+1);
         }
      }

      if ($dopaint && @areas) {
         # a single full clear_area is way faster than many single calls here
         # the "cut-off" point is quite arbitrary
         if (@areas > 64) {
            # update a single rectangle only
            my $rect = new Gtk2::Gdk::Rectangle @{pop @areas};
            $rect = $rect->union (new Gtk2::Gdk::Rectangle @$_) for @areas;
            $self->{window}->clear_area ($rect->values);
         } else {
            # update all the affected rectangles
            $self->{window}->clear_area (@$_) for @areas;
         }
      }
   } else {
      no strict 'refs';

      # straight copy
      $self->{board} = [map [@$_], @$newboard];
      $self->{label} = [map [@$_], @$newlabel];
   }
}

sub cursor {
   my ($self, $show) = @_;

   return unless exists $self->{cursorpos}
                     && $self->{cursor}
                     && $self->{backgroundpb};

   my ($x, $y) = @{$self->{cursorpos}};

   my $mark = $self->{board}[$x][$y];

   $mark = $self->{cursor}->($mark, $x, $y) if $show;

   local $self->{board}[$x][$y] = $mark;
   $self->{window}->clear_area (@{ $self->{draw_stone}->($x + 1, $y + 1) });
}

sub motion {
   my ($self) = @_;

   return unless $self->{backgroundpb};

   my $window = $self->{canvas}->window;
   my (undef, $x, $y, undef) = $window->get_pointer;

   my $size = $self->{size};

   my $x = int (($x - $self->{kx}[0]) * $size / ($self->{kx}[$size] - $self->{kx}[0]) + 0.5) - 1;
   my $y = int (($y - $self->{ky}[0]) * $size / ($self->{ky}[$size] - $self->{ky}[0]) + 0.5) - 1;

   my $pos = $self->{cursorpos};
   if ((not (defined $pos) && $x >= 0 && $x < $size && $y >= 0 && $y < $size)
       || $x != $pos->[0]
       || $y != $pos->[1]) {

      $self->cursor (0);

      if ($x >= 0 && $x < $size
          && $y >= 0 && $y < $size) {
         $self->{cursorpos} = [$x, $y];
         $self->cursor (1);
      } else {
         delete $self->{cursorpos};
      }
   }
}

sub do_button_press {
   my ($self, $button, $x, $y) = @_;
}

sub do_button_release {
   my ($self, $button, $x, $y) = @_;
}

sub button {
   my ($self, $type, $event) = @_;

   $self->motion;

   if ($self->{cursorpos}) {
      $self->signal_emit ("button-$type", $event->button, @{ $self->{cursorpos} });
   }
}

=item Gtk2::GoBoard::play_sound "name"

Play the sound with the give name. Currently supported names are:

   alarm connect gamestart info move outoftime pass resign ring warning

If the L<Audio::Play> module cannot be loaded, the function will silently
fail. If an unsupported sound name is used, the function might C<croak> or
might silently fail.

This function forks a sound-server to play the sound(s) on first use.

=cut

our $SOUND_SERVER;

sub play_sound {
   eval { require Audio::Data; require Audio::Play }
      or return;

   unless ($SOUND_SERVER) {
      require Socket;

      # use this contortion to also work on the broken windows platform
      socketpair $SOUND_SERVER, my $fh, &Socket::AF_UNIX, &Socket::SOCK_STREAM, 0
        or return;

      my $pid = fork;

      if ($pid) {
         # parent
         close $fh;

      } elsif (defined $pid) {
         # child
         close $SOUND_SERVER;

         close STDIN;
         close STDOUT;
         close STDERR;

         # ok, this is a bit pathetic
         POSIX::close $_ for grep $_ != fileno $fh, 3 .. 1000;

         my %sound;

         while (<$fh>) {
            chomp;

            eval {
               my $sound = $sound{$_} ||= do {
                  my $path = findfile "$_.au"
                     or Carp::croak "$_: unable to find sound\n";

                  open my $fh, "<", $path
                     or Carp::croak "$_: unable to load sound\n";

                  binmode $fh;

                  my $data = new Audio::Data;
                  $data->Load ($fh);

                  $data
               };

               my $server = new Audio::Play;
               $server->play ($sound);
               $server->flush;
            };
         }

         # required for windows, as a mere _exit kills your parent process...
         kill 9, $$;
      } else {
         undef $SOUND_SERVER;
         return;
      }
   }

   syswrite $SOUND_SERVER, "$_[0]\n";
}

1;

=back

=head2 EXAMPLE PROGRAM

This program should get you started. It creates a board with some
markings, enables a cursor callback that shows a transparent black stone,
and after a click, marks the position with a circle and disables the
cursor.

   use Gtk2 -init;
   use Games::Go::SimpleBoard;
   use Gtk2::GoBoard;

   my $game = new Games::Go::SimpleBoard 9;

   # show off some markings
   $game->{board}[0][0] = MARK_B;
   $game->{board}[1][1] = MARK_GRAY_B | MARK_SMALL_W;
   $game->{board}[2][2] = MARK_W | MARK_TRIANGLE;
   $game->{board}[1][2] = MARK_B | MARK_LABEL;
   $game->{label}[1][2] = "198";
   $game->{board}[0][2] = MARK_W | MARK_LABEL;
   $game->{label}[0][2] = "AWA";

   # create a spot where black cannot put a stone
   $game->{board}[17][0] = MARK_W;
   $game->{board}[17][1] = MARK_W;
   $game->{board}[18][1] = MARK_W;

   my $board = new Gtk2::GoBoard;
   $board->set_board ($game);

   Gtk2::GoBoard::play_sound "gamestart"; # ping

   # enable cursor for black, till click
   $board->set (cursor => sub {
      my ($mark, $x, $y) = @_;

      $mark |= MARK_GRAYED | MARK_B
         if $game->is_valid_move (COLOUR_BLACK, $x, $y);

      $mark
   });

   # on press, set a mark and disable cursor
   $board->signal_connect (button_release => sub {
      my ($board, $button, $x, $y) = @_;

      $game->{board}[$x][$y] |= MARK_CIRCLE;
      $board->set_board ($game); # force update

      Gtk2::GoBoard::play_sound "move"; # play click sound

      $board->set (cursor => undef); # disable cursor
   });

   my $w = new Gtk2::Window "toplevel";
   $w->set_default_size (450, 450);
   $w->add ($board);
   $w->show_all;

   main Gtk2;

=head2 AUTHOR

Marc Lehmann <schmorp@schmorp.de>

=head2 SEE ALSO

L<App::IGS>, L<Games::Go::SimpleBoard>, L<AnyEvent::IGS>, L<KGS>.

=cut