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/*
Copyright (C) 2012 Carl Hetherington <cth@carlh.net>
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.
*/
#ifndef DVDOMATIC_UI_SIGNALLER_H
#define DVDOMATIC_UI_SIGNALLER_H
#include <boost/bind.hpp>
#include <boost/asio.hpp>
#include <boost/thread.hpp>
/** A class to allow signals to be emitted from non-UI threads and handled
* by a UI thread.
*/
class UISignaller
{
public:
/** Create a UISignaller. Must be called from the UI thread */
UISignaller ()
: _work (_service)
{
_ui_thread = boost::this_thread::get_id ();
}
/** Emit a signal from any thread whose handlers will be called in the UI
* thread. Use something like:
*
* ui_signaller->emit (boost::bind (boost::ref (SomeSignal), parameter));
*/
template <typename T>
void emit (T f) {
if (boost::this_thread::get_id() == _ui_thread) {
/* already in the UI thread */
f ();
} else {
/* non-UI thread; post to the service and wake up the UI */
_service.post (f);
wake_ui ();
}
}
/** Call this in the UI when it is idle */
void ui_idle () {
_service.poll ();
}
/** This should wake the UI and make it call ui_idle() */
virtual void wake_ui () = 0;
private:
/** A io_service which is used as the conduit for messages */
boost::asio::io_service _service;
/** Object required to keep io_service from stopping when it has nothing to do */
boost::asio::io_service::work _work;
/** The UI thread's ID */
boost::thread::id _ui_thread;
};
extern UISignaller* ui_signaller;
#endif
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