fpscounter.cpp

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/* xoreos - A reimplementation of BioWare's Aurora engine
 *
 * xoreos is the legal property of its developers, whose names
 * can be found in the AUTHORS file distributed with this source
 * distribution.
 *
 * xoreos 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.
 *
 * xoreos 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 xoreos. If not, see <http://www.gnu.org/licenses/>.
 */

#include <cassert>

#include "src/common/util.h"

#include "src/graphics/fpscounter.h"

#include "src/events/events.h"

namespace Graphics {

FPSCounter::FPSCounter(size_t secs) : _seconds(secs) {
    assert(_seconds > 0);

    _frames.reset(new uint32[_seconds]);

    reset();
}

FPSCounter::~FPSCounter() {
}

uint32 FPSCounter::getFPS() const {
    return _fps;
}

void FPSCounter::reset() {
    _lastSampled = 0;

    _currentSecond = 0;

    _hasFullSeconds = false;

    _fps = 0;

    for (size_t i = 0; i < _seconds; i++)
        _frames[i] = 0;
}

void FPSCounter::finishedFrame() {
    uint32 now = EventMan.getTimestamp();

    if (_lastSampled == 0)
        _lastSampled = now;

    if ((now - _lastSampled) >= 1000) {
        // We had one second worth of frames

        // Advance to the next second
        _currentSecond = (_currentSecond + 1) % _seconds;
        _lastSampled = now;

        // We filled all samples
        if (_currentSecond == 0)
            _hasFullSeconds = true;

        // Calculate the new FPS value
        calculateFPS();

        // Reset the counter
        _frames[_currentSecond] = 0;
    }

    // Another frame!
    _frames[_currentSecond]++;
}

void FPSCounter::calculateFPS() {
    size_t seconds = _hasFullSeconds ? _seconds : _currentSecond;
    uint32 frames = 0;
    for (size_t i = 0; i < seconds; i++)
        frames += _frames[i];

    _fps = seconds ? (frames / seconds) : 0;
}

} // End of namespace Graphics