How to show a graph in a Perl Gtk GUI?

Question

Using Perl and Gtk2 (or Gtk3), I'd like to display a graph in a GUI application.

Chart::Clicker looks promising, but it seems to only write to files. Is there a way to get that into a GtkDrawingArea or similar?

Answer 1

After lots of experimentation, I figured it out.

1. Don't use Gtk::DrawingArea, use Gtk::Image.
2. $img->set_from_surface($chart->driver->surface);

Reading through the source to Chart::Clicker, I found that $chart->driver is the Cairo object and ->surface is the actual Cairo surface. A Gtk::Image can be directly drawn based on a Cairo surface.

Complete program that illustrates how to do this:

#!/usr/bin/perl -w
use strict;
use Gtk3 -init;
use Chart::Clicker;
use Chart::Clicker::Data::Series;
use Chart::Clicker::Data::DataSet;
my $win = Gtk3::Window->new;
my $img = Gtk3::Image->new;
$win->add($img);
my $chart = Chart::Clicker->new;
my $dataset = Chart::Clicker::Data::DataSet->new(
        series => [Chart::Clicker::Data::Series->new(
                keys => [1, 2, 3, 4, 5],
                values => [2, 3, 5, 7, 11],
        )],
);
$chart->add_to_datasets($dataset);
$chart->draw;
$img->set_from_surface($chart->driver->surface);
$win->signal_connect(destroy => sub{Gtk3->main_quit});
$win->show_all;
Gtk3::main;

Update

On Gtk3 < 3.10, replace the line containing set_from_surface with:

my $loader = Gtk3::Gdk::PixbufLoader->new;
$chart->driver->surface->write_to_png_stream(sub {
    $loader->write([unpack 'C*', $_[1]]);
});
$loader->close;
$img->set_from_pixbuf($loader->get_pixbuf);