use Tk;
use strict;

my $win = MainWindow -> new();
my ($a, $b) = (325, 345);
$win -> geometry("${a}x${b}");
my @fill;
my $cv = $win -> Canvas(-background => 'green', -height => '321', -width => '321') -> pack();
for (0..31) {
    my $x = $_;
    for (0..31) {
        my $y = $_;
        my $rect = $cv -> createRectangle(2+$x*10,2+$y*10,12+$x*10,12+$y*10, -fill => 'lightgrey');
        $fill[$x][$y] = 0;
        $cv -> bind($rect, '<Button-1>',  [\&recolour, $rect, $x, $y]);
    }
}
my $enx = $win -> Entry() -> place(-rely => 1.0, -y => -20, -x => 2);
my $eny = $win -> Entry() -> place(-relx => 1.0, -rely => 1.0, -y => -20, -x => -127);
$win -> Button(-text => 'Exit', -command => sub {exit}) -> pack (-anchor => 's');
MainLoop;

sub recolour() {
    if ($fill[$_[2]][$_[3]] == 0) {
        $cv -> itemconfigure($_[1], -fill => 'red');
        $fill[$_[2]][$_[3]] = 1;
        }
    else {
        $cv -> itemconfigure($_[1], -fill => 'lightgrey');
        $fill[$_[2]][$_[3]] = 0;
    }
    }