The typical way to clear a canvas, is to use $canvas->delete('all'). So you can use $chart->delete('all'), since $chart is actually derived from a canvas. Below is a simple example. You might have trouble reloading it, if you switch from lines to bars, or whatever, but I'm not deleving that far into it. The advice above, to packforget it, then repack a new one is more foolproof, but delete('all') will allow you the possibility to reuse the canvas. Also packforget and repacking may lead to a memory gain if you do it too many times, but I hav'nt tested that.

#!/usr/bin/perl
use strict;
use warnings;
use Tk;
use Tk::Chart::Pie;


my $mw = MainWindow->new( -title => 'Tk::Chart::Pie example', );

my $chart = $mw->Pie(
  -title      => 'There are currently 231 CPAN mirrors around the Worl
+d (20/09/2010 18:50:57).',
  -background => 'white',
  -linewidth  => 2,
)->pack(qw / -fill both -expand 1 /);
print "$chart\n";

# attempt to see if it is a Subwidget
my $canvas = $chart->Subwidget('canvas');
print "$canvas\n";

my @data = ( [ 'Europe', 'Asia', 'Africa', 'Oceania', 'Americas' ], [ 
+119, 33, 3, 6, 67 ], );

$chart->plot( \@data );

my $cbutton = $mw->Button(-text => 'Clear',
         -command => sub{
         
         # $canvas->delete('all');
           $chart->delete('all');
         
         })->pack();

MainLoop();
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