I'm having a big lot of trouble with Graph::Map, and pumping it (and associated graph) out to the browser.

When i generate the graph (png) and store it on the disk, the image map works perfectly. When i pump the image out to the browser without putting it on disk the image map is incorrect, it is longer and fatter than the area it's supposed to be mapping over. I just dont get it.

#!/usr/bin/perl -w

use GD::Graph::bars;
use GD::Graph::Map;
use CGI qw/:standard/;
use Date::Calc qw/Delta_Days Date_to_Text Add_Delta_Days/;

my @data = (
    ["node1"],
);

my @dates = ("11-3-2002","12-4-2002", "15-5-2002","31-12-2002");
my $startdate = $dates[0];

for (my $i=0;$i<$#dates;$i+=1){
    my @basedate = split(/-/, $dates[$i]  );
    my @nextdate = split(/-/, $dates[$i+1]);
    my $dd = Delta_Days($basedate[2],$basedate[1],$basedate[0],
                        $nextdate[2],$nextdate[1],$nextdate[0]);
    push @data, [$dd];
}
my $my_graph = new GD::Graph::bars(200,500);
$my_graph->set_legend( qw(bar1 bar2 bar3));

$my_graph->set(
    x_label         => 'Node',
    y_label         => 'Date',
    title           => "Technology",
    y_max_value     => 365,
    y_tick_number   => 10,
    y_label_skip    => 2,
    y_number_format => \&y_format,
    cumulate        => 1,
    borderclrs      => 'black',
    bar_spacing     => 4,
    bar_width       => 30,
    values_vertical => 1,
    accntclr        => 'lgreen',
    transparent     => 0,
);

if (length (my $info = path_info())) {
    my $format= $my_graph->export_format;
    print header("image/$format"), ($my_graph->plot(\@data))->$format(
+);
    exit 0;
}

$map = new GD::Graph::Map($my_graph, info => '%l:  x=%x   y=%y');
$HTML_Map = $map->imagemap(url()."/sample15.png", \@data);

print header;
print "bit of text here";
print $HTML_Map;

sub y_format {
    my $val = shift;
    my @ysd = split(/-/, $startdate);
    my @delta = Add_Delta_Days($ysd[2],$ysd[1],$ysd[0], int($val) );
    return substr(Date_to_Text(@delta), 4);
}
[download]

boo_radley has a good node that covers Graph::Map however doesnt go into "no disk hits".

As a slight aside, I'm attempting to do this as it will save on IO, and I wont have to write a scavange routine to trash the old graphs. The site will only ever have a small load...

If anyone has any experience in doing this, I would appreciate to hear from you.

No this is not production code... :-)