use Tk;
$top = new MainWindow;
$p = $top->Photo(-width => 400, -height => 300);
$c = $top->Canvas(-width => 400, -height => 300)->pack(-fill => "both", -expand => 1);
$img = $c->createImage(0,0,-image=>$p,-anchor=>"nw");
for my $x (-$p->width/2 .. $p->width/2) {
    my($tx) = int($x+$p->width/2);
    my $y = sin($x/10)*$p->height/2;
    my($ty) = int($y+$p->height/2);
    $p->put("#ff0000", -to => $tx,$ty+1,$tx+1,$ty);
}
MainLoop;