#!/usr/bin/perl -w
use strict;
use warnings;
use Goo::Canvas;
use Gtk2 '-init';
use Glib qw(TRUE FALSE);

my $window = Gtk2::Window->new('toplevel');
$window->signal_connect('delete_event' => sub { Gtk2->main_quit; });
$window->set_default_size(640, 600);

my $swin = Gtk2::ScrolledWindow->new;
$swin->set_shadow_type('in');
$window->add($swin);

my $canvas = Goo::Canvas->new();
$canvas->set_size_request(600, 450);
$canvas->set_bounds(0, 0, 1000, 1000);
$swin->add($canvas);

my $root = $canvas->get_root_item();

# base file
my $im = Gtk2::Gdk::Pixbuf->new_from_file("MI.png");
my $w = $im->get_width;
my $h = $im->get_height;
my $image = Goo::Canvas::Image->new(
$root, $im, 0, 0,
'width' => $w,
'height' => $h);

# overlay file which needs transparency added
my $im1 = Gtk2::Gdk::Pixbuf->new_from_file("zzrgbwb.png");
my $im2 = $im1->add_alpha(1,0 ,255 , 0); 
# returns a new pixbuf
# makes green transparent
# use 0..255 for color levels, NOT hex

my $w1 = $im2->get_width;
my $h1 = $im2->get_height;
my $image1 = Goo::Canvas::Image->new(
$root, $im2, 50, 50,
'width' => $w,
'height' => $h);

$window->show_all();
Gtk2->main;

##</code><code>##

#!/usr/bin/perl
use warnings;
use strict;
use GD;

GD::Image->trueColor(1);

my $img_file = 'zzrgbwb.png';

my $gd = GD::Image->new($img_file) or die;
my ($w, $h) = $gd->getBounds();
print "$w $h\n";

# allocate some colors
my $white = $gd->colorAllocate(255,255,255);
my $black = $gd->colorAllocate(0,0,0);
my $red = $gd->colorAllocate(255,0,0);
my $green = $gd->colorAllocate(0,255,0);
my $blue = $gd->colorAllocate(0,0,255);

# make the background transparent and interlaced
$gd->transparent($green);
#$gd->interlaced('true');

open(GD, ">zzrgbwb-gt.png") or die;
binmode GD;
print GD $gd->png;
close GD;