Add PBD::Timer/StandardTimer/BlinkTimer classes for convenient timeouts

1 files changed, 156 insertions, 0 deletions

diff --git a/libs/pbd/timer.cc b/libs/pbd/timer.cc
new file mode 100644
index 0000000000..662c7ddc38
--- /dev/null
+++ b/libs/pbd/timer.cc
@@ -0,0 +1,156 @@
+/*
+    Copyright (C) 2014 Tim Mayberry
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+*/
+
+#include "pbd/timer.h"
+
+namespace PBD {
+
+Timer::Timer (unsigned int interval,
+              const Glib::RefPtr<Glib::MainContext>& main_context)
+	: m_timeout_source(NULL)
+	, m_timeout_interval(interval)
+	, m_main_context(main_context)
+{
+
+}
+
+gboolean
+Timer::_timeout_handler (void *data)
+{
+	Timer *const timer = static_cast<Timer*>(data);
+	return timer->timeout_handler();
+}
+
+unsigned int
+Timer::get_interval () const
+{
+	return m_timeout_interval;
+}
+
+void
+Timer::set_interval (unsigned int new_interval)
+{
+	if (new_interval == m_timeout_interval) return;
+
+	stop ();
+	m_timeout_interval = new_interval;
+	start ();
+}
+
+/**
+ * We don't use Glibmm::TimeoutSource::create() here as contrary
+ * to the documentation, SignalTimeout::connect and manually
+ * adding a TimeoutSource to a GMainContext are not equivalent.
+ *
+ * SignalTimeout::connect is the equivalent of g_timeout_add in
+ * terms off callback timing but TimeoutSource tries to adjust
+ * the timeout based on the time elapsed since the last timeout.
+ *
+ * On Windows with a high frequency timeout(40ms) this causes a
+ * small but noticable increase in CPU Usage.
+ */
+void
+Timer::start()
+{
+	if (m_timeout_source) return;
+
+	m_timeout_source = g_timeout_source_new (m_timeout_interval);
+
+#if 0 // support priorites?
+	if(priority != G_PRIORITY_DEFAULT)
+		g_source_set_priority(source, priority);
+#endif
+
+	g_source_set_callback (m_timeout_source, &Timer::_timeout_handler, this, NULL);
+
+	g_source_attach (m_timeout_source, m_main_context->gobj());
+	// GMainContext also holds a reference
+}
+
+void
+Timer::stop()
+{
+	if (m_timeout_source) {
+		g_source_destroy (m_timeout_source);
+		g_source_unref (m_timeout_source);
+		m_timeout_source = NULL;
+	}
+}
+
+bool
+Timer::timeout_handler()
+{
+	return on_elapsed();
+}
+
+StandardTimer::StandardTimer(unsigned int interval,
+		const Glib::RefPtr<Glib::MainContext>& main_context)
+	: Timer(interval, main_context)
+{ }
+
+sigc::connection
+StandardTimer::connect(const sigc::slot<void>& slot)
+{
+	if(m_signal.size() == 0) { start(); }
+
+	return m_signal.connect(slot);
+}
+
+bool
+StandardTimer::on_elapsed()
+{
+	if(m_signal.size() == 0)
+	{
+		stop();
+		return false;
+	}
+
+	m_signal();
+	return true;
+}
+
+BlinkTimer::BlinkTimer(unsigned int interval,
+		const Glib::RefPtr<Glib::MainContext>& main_context)
+	: Timer(interval, main_context)
+{ }
+
+sigc::connection
+BlinkTimer::connect(const sigc::slot<void, bool>& slot)
+{
+	if(m_blink_signal.size() == 0) { start(); }
+
+	return m_blink_signal.connect(slot);
+}
+
+bool
+BlinkTimer::on_elapsed()
+{
+	static bool blink_on = false;
+
+	if(m_blink_signal.size() == 0)
+	{
+		stop();
+		return false;
+	}
+
+	m_blink_signal(blink_on = !blink_on);
+	return true;
+}
+
+} // namespace PBD