SynchroTimer.h

/* 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 QDENGINE_QDCORE_UTIL_SYNCRO_TIMER
#define QDENGINE_QDCORE_UTIL_SYNCRO_TIMER

#include "common/system.h"

typedef uint32 time_type;

namespace QDEngine {

class SyncroTimer {
public:
    // Main property
    time_type operator()() const {
        return round(_time);
    }
    // Last delta
    time_type delta() const {
        return _time - _time_prev;
    }

    SyncroTimer() {
        set(1, 15, 100);
        _time_prev = _time = 1;
        _time_offset = 0;
        _time_speed = 1;
    }

    void set(int syncro_by_clock, time_type time_per_frame, time_type max_time_interval) {
        _syncro_by_clock = syncro_by_clock;
        _time_per_frame = time_per_frame;
        _max_time_interval = max_time_interval;
    }

    SyncroTimer &adjust() {
        _time_prev = _time;

        if (_syncro_by_clock) {
            float t = float(g_system->getMillis());
            float dt = (t - _time - _time_offset) * _time_speed;
            if (dt > _max_time_interval)
                dt = _max_time_interval;
            _time += dt;
            _time_offset = t - _time;
        }
        return *this;
    }

    void next_frame() {
        if (_syncro_by_clock)
            adjust();
        else {
            _time_prev = _time;
            _time += _time_per_frame * _time_speed;
//          _time += round(_time_per_frame*_time_speed);
        }
    }

    void skip() {
        if (_syncro_by_clock)
            _time_offset = g_system->getMillis() - _time;
    }

    void setTime(time_type t) {
        _time_prev = _time = t;
        _time_offset = _syncro_by_clock ? g_system->getMillis() - _time : 0;
    }

    void setSpeed(float speed) {
        _time_speed = speed;
    }

private:
    float _time;
    float _time_prev;
    float _time_offset;
    time_type _max_time_interval;
    time_type _time_per_frame;
    int _syncro_by_clock;
    float _time_speed;
};

} // namespace QDEngine

#endif // QDENGINE_QDCORE_UTIL_SYNCRO_TIMER