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common/osd_message_queue.h

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+/* 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 3 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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#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/ustr.h"
+#include "common/queue.h"
+#include "common/mutex.h"
+
+namespace Common {
+
+/**
+ * @defgroup common_osd_message_queue OSD message queue
+ * @ingroup common
+ *
+ * @brief API for managing the queue of On Screen Display (OSD) messages.
+ * @{
+ */
+
+/**
+ * Queue OSD messages from any thread to be displayed by the graphic thread.
+ */
+class OSDMessageQueue : public Singleton<OSDMessageQueue>, public EventSource {
+public:
+	OSDMessageQueue();
+	~OSDMessageQueue();
+
+	void registerEventSource();
+
+	enum {
+		kMinimumDelay = 1000 /** < Minimum delay between two OSD messages (in milliseconds) */
+	};
+
+	/**
+	 * Add a message to the OSD message queue.
+	 */
+	void addMessage(const Common::U32String &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.
+	 */
+	bool pollEvent(Common::Event &event) override;
+
+private:
+	Mutex _mutex;
+	Queue<U32String> _messages;
+	uint32 _lastUpdate;
+};
+
+/** @} */
+
+} // End of namespace Common
+
+#endif