livetrax/libs/pbd/timer.cc

/*
    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