ZVISION: Create Clock class to handle deltaTime while pausing and unpausing the game

2 files changed, 146 insertions, 0 deletions

diff --git a/engines/zvision/clock.cpp b/engines/zvision/clock.cpp
new file mode 100644
index 0000000000..2324d395c3
--- /dev/null
+++ b/engines/zvision/clock.cpp
@@ -0,0 +1,68 @@
+/* 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/scummsys.h"
+
+#include "common/system.h"
+
+#include "zvision/clock.h"
+
+namespace ZVision {
+
+Clock::Clock(OSystem *system) 
+	: _system(system),
+	  _lastTime(0),
+	  _deltaTime(0),
+	  _pausedTime(0),
+	  _paused(false) {
+}
+
+void Clock::update() {
+	uint32 currentTime = _system->getMillis();
+	_deltaTime = currentTime - _lastTime - _pausedTime;
+	if (_deltaTime < 0) {
+		_deltaTime = 0;
+	}
+
+	if (_paused) {
+		_pausedTime += _deltaTime;
+	} else if (_pausedTime > 0) {
+		_pausedTime = 0;
+	}
+
+	_lastTime = currentTime;
+}
+
+void Clock::start() {
+	if (_paused) {
+		_paused = false;
+	}
+}
+
+void Clock::stop() {
+	if (!_paused) {
+		_paused = true;
+	}
+}
+
+} // End of namespace ZVision
diff --git a/engines/zvision/clock.h b/engines/zvision/clock.h
new file mode 100644
index 0000000000..d17db6c255
--- /dev/null
+++ b/engines/zvision/clock.h
@@ -0,0 +1,78 @@
+/* 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 ZVISION_CLOCK_H
+#define ZVISION_CLOCK_H
+
+#include "common/types.h"
+
+class OSystem;
+
+namespace ZVision {
+
+/* Class for handling frame to frame deltaTime while keeping track of time pauses/un-pauses */
+class Clock {
+public:
+	Clock(OSystem *system);
+
+private:
+	OSystem *_system;
+	uint32 _lastTime;
+	uint32 _deltaTime;
+	uint32 _pausedTime;
+	bool _paused;
+
+public:
+	/**
+	 * Updates _deltaTime with the difference between the current time and
+	 * when the last update() was called.
+	 */
+	void update();
+	/**
+	 * Get the delta time since the last frame. (The time between update() calls)
+	 *
+	 * @return    Delta time since the last frame (in milliseconds)
+	 */
+	uint32 getDeltaTime() const { return _deltaTime; }
+	/**
+	 * Get the time from the program starting to the last update() call
+	 *
+	 * @return Time from program start to last update() call (in milliseconds)
+	 */
+	uint32 getLastMeasuredTime() { return _lastTime; }
+
+	/**
+	 * Pause the clock. Any future delta times will take this pause into account.
+	 * Has no effect if the clock is already paused.    
+	 */
+	void start();
+	/**
+	 * Un-pause the clock.
+	 * Has no effect if the clock is already un-paused.    
+	 */
+	void stop();
+};
+
+} // End of namespace ZVision
+
+#endif