neilwatson has asked for the wisdom of the Perl Monks concerning the following question:

This is my first try with GD::Graph. I'd like to 'print' the image directly to the browser without having to save it via a filehandle. Alas it is not yet working. What have I missed? 

<%perl>

use GD::Graph::bars;
use Data::Dumper;

my ($x, $y, @numbers, $number);

my @data = (
    # X axis
    [ qw( -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 )]
);

# loop for each success level
for ($x = 1, $x < 5, $x++){

    # generate numbers for each skill level
    for ($y = 1, $y < 19, $y++){

        $number = $x*$y*2+5;
        push @numbers, $number;
    }
    push @data, [@numbers];
}

my $graph = new GD::Graph::bars();
$graph->set(
    title       => 'Skill Resolution',
    x_label     => 'Skill Level',
    y_label     => 'Success Level'
);

my $gd = $graph->plot(\@data) or die "Could not plot: ".$graph->error.
    Dumper(@data);

print "Content-type:  image/png\n\n";
print $gd->png();

</%perl>

[download]
Yes, this is done through Mason.

Neil Watson
watson-wilson.ca

Replies are listed 'Best First'.
Re: GD::Graph without saving file
by PodMaster (Abbot) on Jul 07, 2004 at 23:33 UTC
    1. You're forgetting to binmode. 2. That's not how you deal with headers in mason (see Re: OT: HTML::Mason & apache redirects)

    MJD says "you can't just make shit up and expect the computer to know what you mean, retardo!"
    I run a Win32 PPM repository for perl 5.6.x and 5.8.x -- I take requests (README).
    ** The third rule of perl club is a statement of fact: pod is sexy.

[reply]
      OK so using binmode and the Mason way of headers (all within %init instead of %perl): 

      ....snip...

my $gd = $graph->plot(\@data) or die "Could not plot: ".$graph->error.
    Dumper(@data);
my $img = $gd->png();

$r->content_type("image/png");
$r->send_http_header;
binmode STDOUT;
$m->print($img);
$m->abort(OK);  # make sure nothing else gets sent

      [download]
      Still not working.

      Neil Watson
      watson-wilson.ca

[reply]
[d/l]

        Still not working.

        If you comment out the 

          $m->print($img);

        [download]

        line and make the request by hand (e.g., in a telnet session to port 80), what do the headers look like?

[reply]
[d/l]
[reply]
        Why? Just binmode, it can't hurt.

        MJD says "you can't just make shit up and expect the computer to know what you mean, retardo!"
        I run a Win32 PPM repository for perl 5.6.x and 5.8.x -- I take requests (README).
        ** The third rule of perl club is a statement of fact: pod is sexy.

[reply]
Re: GD::Graph without saving file
by neilwatson (Priest) on Jul 12, 2004 at 13:36 UTC
    Here is the working code: 

    <%init>

use GD::Graph::bars;
use Data::Dumper;

my ($x, $y, @numbers, $number);

my @data = (
    # X axis
    [ qw( -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 )]
);

# loop for each success level
for ($x = 1; $x < 5; $x++){

    # generate numbers for each skill level
    for ($y = 1; $y < 19; $y++){

        $number = $x*$y*2+5;
        push @numbers, $number;
    }
    push @data, [@numbers];
    @numbers = 0;
}

my $graph = new GD::Graph::bars();
$graph->set(
    title       => 'Skill Resolution',
    x_label     => 'Skill Level',
    y_label     => 'Success Level'
);

my $gd = $graph->plot(\@data) or die "Could not plot: ".$graph->error.
    Dumper(@data);
my $img = $gd->png();

$m->clear_buffer;
$r->content_type("image/png");
$r->send_http_header;
binmode STDOUT; 
$m->out($img);
$m->abort(OK);  # make sure nothing else gets sent

</%init>

    [download]

    Neil Watson
    watson-wilson.ca

[reply]
[d/l]

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