// Copyright (c) 2017 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#ifndef BITCOIN_QT_MODALOVERLAY_H
#define BITCOIN_QT_MODALOVERLAY_H

#include <QDateTime>
#include <QWidget>

//! The required delta of headers to the estimated number of available headers until we show the IBD progress
static constexpr int HEADER_HEIGHT_SYNC_DELTA = 24;

namespace Ui
{
class ModalOverlay;
}

/** Modal overlay to display information about the chain-sync state */
class ModalOverlay : public QWidget
{
    Q_OBJECT

public:
    explicit ModalOverlay(QWidget *parent);
    ~ModalOverlay();

public Q_SLOTS:
    void tipUpdate(int count, const QDateTime &blockDate, double nVerificationProgress);
    void setKnownBestHeight(int count, const QDateTime &blockDate);

    // will show or hide the modal layer
    void showHide(bool hide = false, bool userRequested = false);
    void closeClicked();

protected:
    bool eventFilter(QObject *obj, QEvent *ev);
    bool event(QEvent *ev);

private:
    Ui::ModalOverlay *ui;
    std::atomic<int> bestBlockHeight{0}; // best known height (based on the headers)
    QVector<QPair<qint64, double> > blockProcessTime;
    bool layerIsVisible;
    bool userClosed;
};

#endif // BITCOIN_QT_MODALOVERLAY_H

// Copyright (c) 2017 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#ifndef BITCOIN_QT_MODALOVERLAY_H
#define BITCOIN_QT_MODALOVERLAY_H

#include <QDateTime>
#include <QWidget>
#include <atomic>

//! The required delta of headers to the estimated number of available headers until we show the IBD progress
static constexpr int HEADER_HEIGHT_SYNC_DELTA = 24;

namespace Ui
{
class ModalOverlay;
}

/** Modal overlay to display information about the chain-sync state */
class ModalOverlay : public QWidget
{
    Q_OBJECT

public:
    explicit ModalOverlay(QWidget *parent);
    ~ModalOverlay();

public Q_SLOTS:
    void tipUpdate(int count, const QDateTime &blockDate, double nVerificationProgress);
    void setKnownBestHeight(int count, const QDateTime &blockDate);

    // will show or hide the modal layer
    void showHide(bool hide = false, bool userRequested = false);
    void closeClicked();

protected:
    bool eventFilter(QObject *obj, QEvent *ev);
    bool event(QEvent *ev);

private:
    Ui::ModalOverlay *ui;
    std::atomic<int> bestBlockHeight{0}; // best known height (based on the headers)
    QVector<QPair<qint64, double> > blockProcessTime;
    bool layerIsVisible;
    bool userClosed;
};

#endif // BITCOIN_QT_MODALOVERLAY_H

Add a missing atomic include
Add a missing atomic include

This prevent this error in Ubuntu xenial and trusty while compling bitcoin-qt:

In file included from qt/modaloverlay.cpp:5:0:
qt/modaloverlay.h:42:10: error: ‘atomic’ in namespace ‘std’ does not name a template type
     std::atomic<int> bestBlockHeight{0}; // best known height (based on the headers)
                   ^
