如何摆脱Perl的GD :: Graph中的饼图轮廓？

accentclr => 'black',

所以我希望通过这样做可以完全摆脱轮廓：

accentclr => undef,

然而,当我这样做时,轮廓确实消失了,但饼图的其余部分也是如此,只剩下标签！

这是我的脚本的简化版本：

#!/usr/bin/env perl
use GD::Graph::pie;

# Data to be graphed: 1st array is labels,2nd array is data
my @data = ( 
     ["1st","2nd","3rd","4th"],[ 1,3.5,5,6 ],);
my $graph = GD::Graph::pie->new(400,400);

$graph->set(      
#   accentclr   => undef,'3d'            => 0,) or die $graph->error;

my $gd = $graph->plot(@data) or die $graph->error;

open(IMG,'>pie.png') or die $!;
binmode IMG;
print IMG $gd->png;