fps.cpp

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#include "fps.h"

#include <QtCore/qdatetime.h>
#include <QtGui/qbrush.h>
#include <QtGui/qpainter.h>

FPS::FPS(QQuickItem *parent): QQuickPaintedItem(parent), m_currentFPS(0), m_cachedFPS(0)
{
    m_paintPasses.clear();
    setFlag(QQuickItem::ItemHasContents);
}

FPS::~FPS()
{
}

void FPS::updateFPS()
{
    qint64 currentTime = QDateTime::currentDateTime().toMSecsSinceEpoch();
    m_paintPasses.push_back(currentTime);

    while (m_paintPasses[0] < currentTime - 1000)
        m_paintPasses.pop_front();

    int currentCount = m_paintPasses.length();
    m_currentFPS = (currentCount + m_cachedFPS) / 2;

    if (currentCount != m_cachedFPS)
        fpsChanged(m_currentFPS);

    m_cachedFPS = currentCount;
}

int FPS::fps()const
{
    return m_currentFPS;
}

void FPS::paint(QPainter *painter)
{
    updateFPS();
    painter->setPen(Qt::NoPen);
    painter->setRenderHint(QPainter::Antialiasing);
    painter->drawRoundedRect(0, 0, boundingRect().width(), boundingRect().height(), 0, 0);

    update();
}