#!/usr/bin/perl -w

use strict;

use constant WIDTH	=> 1000;
use constant HEIGHT	=> 100;
use constant SPEED	=> 1;

use Cairo;
use Glib qw(TRUE FALSE);
use Gtk2 -init;
use Gtk2::Pango;

my ($text,$ticks, $cr, $layout, $desc, $area);

sub initialize {
	$cr = Gtk2::Gdk::Cairo::Context -> create($area->window());
	$layout = Gtk2::Pango::Cairo::create_layout($cr);
	$desc = Gtk2::Pango::FontDescription -> from_string("Sans Bold 57");
	$layout -> set_font_description($desc);
	$layout->set_alignment("PANGO_ALIGN_LEFT");
}

sub draw_text {
	$cr->push_group;	
	$layout->set_text($text);


	Gtk2::Pango::Cairo::update_layout($cr, $layout);

	my @size = $layout->get_pixel_size;
	
	$cr -> translate(-($ticks*SPEED)%$size[0],0);

	$cr->set_source_rgb(1.0,1.0,1.0);
	$cr->fill();
	$cr -> set_source_rgb(0.0,0.0,0.0);
	
	my $count = int(WIDTH/$size[0]);
	
	$cr->translate(-$size[0]*2,0);
	
	for(my $i = 0; $i<=$count+1; $i++){
		$cr->translate($size[0],0);
		Gtk2::Pango::Cairo::show_layout($cr,$layout);
	}
	$cr->pop_group_to_source;
	$cr->paint;
}

my $window = Gtk2::Window->new();
$window -> signal_connect(delete_event => sub {
	Gtk2 -> main_quit();
});

$area = Gtk2::DrawingArea -> new();

sub draw {
	$cr->rectangle(0,0,WIDTH,HEIGHT);
	draw_text($cr,$ticks);
}


sub timer {
	$ticks ++;
	draw();
	return 1;
}


$text = 'Please specify your input file';
if($ARGV[0]){
	open(INPUT_FILE, "$ARGV[0]");
	$text = <INPUT_FILE>;
}

$ticks = 0;

$window -> set_default_size(WIDTH,HEIGHT);
$window -> add($area);

$window->show_all();

initialize;
my $timer = Glib::Timeout->add(1000/60, \&timer ,'',);
Gtk2->main();