G'day KuntalBhusan,

You haven't defined either $x or $y in $canvas->rotate($text,90,$x,$y);.

Looking at Tk::AbstractCanvas' Source, you'll see these values must be defined (the return() unless ... line):

sub rotate { # takes as input id of obj to rot, angle to rot by, && op
+tional x,y point to rot about instead of obj center, if possible
  my($self, $obid, $angl, $xfoc, $yfoc)= @_; croak "rotate: Must suppl
+y an angle -" unless(defined($angl));
  my $type = $self->type($obid); # some objs need a pivot point to rot
+ate their center around
  return() unless(exists($_can_rotate_about_center{$type}) || (defined
+($xfoc) && defined($yfoc)));
  $_rotate_methods{$type}->($self, $obid, $angl, $xfoc, $yfoc);
}
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