3 files changed, 130 insertions, 0 deletions
diff --git a/common/module.mk b/common/module.mk
index 54aa16f557..6742fef3e8 100644
--- a/common/module.mk
+++ b/common/module.mk
@@ -23,6 +23,7 @@ MODULE_OBJS := \
 	memorypool.o \
 	md5.o \
 	mutex.o \
+	osd_message_queue.o \
 	platform.o \
 	quicktime.o \
 	random.o \
diff --git a/common/osd_message_queue.cpp b/common/osd_message_queue.cpp
new file mode 100644
index 0000000000..ee2ee2d7c8
--- /dev/null
+++ b/common/osd_message_queue.cpp
@@ -0,0 +1,59 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#include "common/osd_message_queue.h"
+#include "common/system.h"
+
+namespace Common {
+
+DECLARE_SINGLETON(OSDMessageQueue);
+	
+OSDMessageQueue::OSDMessageQueue() : _lastUpdate(0) {
+	g_system->getEventManager()->getEventDispatcher()->registerSource(this, false);
+}
+
+OSDMessageQueue::~OSDMessageQueue() {
+	g_system->getEventManager()->getEventDispatcher()->unregisterSource(this);
+}
+	
+void OSDMessageQueue::addMessage(const char *msg) {
+	_mutex.lock();
+	_messages.push(msg);
+	_mutex.unlock();
+}
+
+bool OSDMessageQueue::pollEvent(Common::Event &event) {
+	_mutex.lock();
+	if (!_messages.empty()) {
+		uint t = g_system->getMillis();
+		if (t - _lastUpdate >= kMinimumDelay) {
+			_lastUpdate = t;
+			String msg = _messages.pop();
+			g_system->displayMessageOnOSD(msg.c_str());
+		}
+	}
+	_mutex.unlock();
+
+	return false;
+}
+
+} // End of namespace Common
diff --git a/common/osd_message_queue.h b/common/osd_message_queue.h
new file mode 100644
index 0000000000..9348497b28
--- /dev/null
+++ b/common/osd_message_queue.h
@@ -0,0 +1,70 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#ifndef COMMON_OSD_MESSAGE_QUEUE_H
+#define COMMON_OSD_MESSAGE_QUEUE_H
+
+#include "common/events.h"
+#include "common/singleton.h"
+#include "common/str.h"
+#include "common/queue.h"
+#include "common/mutex.h"
+
+namespace Common {
+
+/**
+ * Queue OSD messages from any thread to be displayed by the graphic thread.
+ */
+class OSDMessageQueue : public Singleton<OSDMessageQueue>, public EventSource {
+public:
+	OSDMessageQueue();
+	~OSDMessageQueue();
+	
+	enum {
+		kMinimumDelay = 1000 /** < Minimum delay between two OSD messages (in milliseconds) */
+	};
+
+	/**
+	 * Add a message to the OSD message queue.
+	 */
+	void addMessage(const char *msg);
+	
+	/**
+	 * Common::EventSource interface
+	 *
+	 * The OSDMessageQueue registers itself as an event source even if it does not
+	 * actually produce events as a mean to be polled periodically by the GUI or
+	 * engine code.
+	 *
+	 * The periodical polling is used to update the OSD messages.
+	 */
+	virtual bool pollEvent(Common::Event &event) override;
+
+private:
+	Mutex _mutex;
+	Queue<String> _messages;
+	uint32 _lastUpdate;
+};
+
+} // End of namespace Common
+
+#endif