[perl-Gtk2] Add an example that renders a clock with Cairo

[Torsten Schönfeld <tsch src gnome org>]

commit 0a86583a12b8052ffa0ae74662a1038e1646d7ba
Author: Torsten Schönfeld <kaffeetisch gmx de>
Date:   Mon May 10 23:50:17 2010 +0200

    Add an example that renders a clock with Cairo

 examples/cairo-clock.pl |  174 +++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 174 insertions(+), 0 deletions(-)
---
diff --git a/examples/cairo-clock.pl b/examples/cairo-clock.pl
new file mode 100644
index 0000000..482d7b3
--- /dev/null
+++ b/examples/cairo-clock.pl
@@ -0,0 +1,174 @@
+# This is a Perl port of the EggClockFace code by Davyd Madeley presented in
+# <http://gnomejournal.org/article/34/writing-a-widget-using-cairo-and-gtk28>,
+# and
+# <http://gnomejournal.org/article/36/writing-a-widget-using-cairo-and-gtk28-part-2>.
+#
+# For the original C code:
+#   Copyright (c) 2005-2006, Davyd Madeley <davyd madeley id au>
+#
+# Unfortunately, I don't remember who wrote the Perl port.
+
+package Egg::ClockFace;
+
+use warnings;
+use strict;
+
+use Glib qw/TRUE FALSE/;
+use Gtk2;
+use Cairo;
+use Math::Trig;
+
+use Glib::Object::Subclass
+	Gtk2::DrawingArea::,
+	signals => {
+		expose_event => \&expose,
+	};
+
+sub min { return ($_[0] < $_[1] ? $_[0] : $_[1]); }
+
+sub draw
+{
+	my $self = shift;
+	my $cr = $self->{cr};
+
+	return FALSE unless $cr;
+
+	my $width  = $self->allocation->width;
+	my $height = $self->allocation->height;
+	
+	$cr->scale($width, $height);
+	$cr->translate(0.5, 0.5);
+	$cr->set_line_width($self->{line_width});
+	
+	$cr->save;
+	$cr->set_source_rgba (0.337, 0.612, 0.117, 0.9);
+	$cr->paint;
+	$cr->restore;
+	$cr->arc (0, 0, $self->{radius}, 0, 2 * Math::Trig::pi);
+	$cr->save;
+	$cr->set_source_rgba (1.0, 1.0, 1.0, 0.8);
+	$cr->fill_preserve;
+	$cr->restore;
+	$cr->stroke_preserve;
+	$cr->clip;
+
+	for (1 .. 12) {
+		my $inset = 0.05;
+
+		$cr->save;
+		$cr->set_line_cap('round');
+
+		if ($_ % 3 != 0) {
+			$inset *= 0.8;
+			$cr->set_line_width(0.03);
+		}
+
+		$cr->move_to(($self->{radius} - $inset) * cos ($_ * Math::Trig::pi / 6),
+		             ($self->{radius} - $inset) * sin ($_ * Math::Trig::pi / 6));
+		$cr->line_to($self->{radius} * cos ($_ * Math::Trig::pi / 6),
+		             $self->{radius} * sin ($_ * Math::Trig::pi / 6));
+
+		$cr->stroke;
+		$cr->restore;
+	}
+
+	my @time    = localtime;
+	my $hours   = $time[2] * Math::Trig::pi / 6;
+	my $minutes = $time[1] * Math::Trig::pi / 30;
+	my $seconds = $time[0] * Math::Trig::pi / 30;
+	
+	$cr->save;
+	$cr->set_line_cap('round');
+	
+	# seconds
+	$cr->save;
+	$cr->set_line_width($self->{line_width} / 3);
+	$cr->set_source_rgba(1.0, 0.0, 0.0, 0.8);
+	$cr->move_to(0, 0);
+	$cr->line_to(     sin($seconds) * ($self->{radius} * .9),
+	             -1 * cos($seconds) * ($self->{radius} * .9));
+	$cr->stroke;
+	$cr->restore;
+	
+	# minutes;
+	$cr->set_source_rgba(0.7, 0.7, 0.7, 0.8);
+	$cr->move_to(0, 0);
+	$cr->line_to(     sin($minutes + $seconds / 60) * ($self->{radius} * 0.8),
+	             -1 * cos($minutes + $seconds / 60) * ($self->{radius} * 0.8));
+	$cr->stroke;
+	
+	# hours
+	$cr->set_source_rgba(0.117, 0.337, 0.612, 0.9);
+	$cr->move_to(0, 0);
+	$cr->line_to(     sin($hours + $minutes / 12.0) * ($self->{radius} * 0.5),
+	             -1 * cos($hours + $minutes / 12.0) * ($self->{radius} * 0.5));
+	$cr->stroke;
+	
+	$cr->restore;
+	
+	# dot
+	$cr->arc(0, 0,  $self->{line_width} / 3.0, 0, 2 * Math::Trig::pi);
+	$cr->fill;
+
+	return TRUE;
+}
+
+sub expose
+{
+	my ($self, $event) = @_;
+
+	my $cr = Gtk2::Gdk::Cairo::Context->create($self->window);
+	$cr->rectangle ($event->area->x,
+			$event->area->y,
+			$event->area->width,
+			$event->area->height);
+	$cr->clip;
+	$self->{cr} = $cr;
+	
+	$self->draw;
+
+	$self->{timeout} = Glib::Timeout->add(1000, sub {
+			my $self = shift;
+			
+			my $alloc = $self->allocation;
+			my $rect = Gtk2::Gdk::Rectangle->new(0, 0, $alloc->width, $alloc->height);
+			$self->window->invalidate_rect($rect, FALSE);
+
+			return TRUE;
+		}, $self) unless $self->{timeout};
+
+	return FALSE;
+}
+
+sub INIT_INSTANCE
+{
+	my $self = shift;
+
+	$self->{line_width} = 0.05;
+	$self->{radius}     = 0.42;
+}
+
+sub FINALIZE_INSTANCE
+{
+	my $self = shift;
+
+	Glib::Source->remove($self->{timeout}) if $self->{timeout};
+}
+
+1;
+
+package main;
+
+use Gtk2 '-init';
+
+my $window = Gtk2::Window->new('toplevel');
+my $clock = Egg::ClockFace->new;
+
+$window->add($clock);
+$window->signal_connect(destroy => sub { Gtk2->main_quit; });
+
+$window->show_all;
+
+Gtk2->main;
+
+0;