kis_signal_compressor.h

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/*
 *  SPDX-FileCopyrightText: 2013 Dmitry Kazakov <dimula73@gmail.com>
 *
 *  SPDX-License-Identifier: GPL-2.0-or-later
 */
 
#ifndef __KIS_SIGNAL_COMPRESSOR_H
#define __KIS_SIGNAL_COMPRESSOR_H
 
#include <QObject>
#include "kritaglobal_export.h"
 
#include <QElapsedTimer>
#include <functional>
 
class QTimer;
 
class KRITAGLOBAL_EXPORT KisSignalCompressor : public QObject
{
    Q_OBJECT
 
public:
    enum Mode {
        POSTPONE, /* Calling start() resets the timer to \p delay ms */
        FIRST_ACTIVE_POSTPONE_NEXT, /* emits the first signal and postpones all the next ones */
        FIRST_ACTIVE, /* Emit timeout() signal immediately. Throttle further timeout() to rate of one per \p delay ms */
        FIRST_INACTIVE, /* Set a timer \p delay ms, Q_EMIT timeout() when it elapses. Ignore all events meanwhile. */
        UNDEFINED /* KisSignalCompressor is created without an explicit mode */
    };
 
    enum SlowHandlerMode {
        PRECISE_INTERVAL, /* Interval of timeout is forced to \p delay ms, whatever time the handler of timeout() takes */
        ADDITIVE_INTERVAL /* When the handler of timeout() is slow, the timeout delay is increased to the (delay + handler_time) */
    };
 
public:
    KisSignalCompressor();
    KisSignalCompressor(int delay, Mode mode, QObject *parent = 0);
    KisSignalCompressor(int delay, Mode mode, SlowHandlerMode slowHandlerMode, QObject *parent = 0);
    bool isActive() const;
    void setMode(Mode mode);
 
    int delay() const;
 
    void setDelay(std::function<bool()> idleCallback, int idleDelay, int timeout);
 
public Q_SLOTS:
    void setDelay(int delay);
    void start();
    void stop();
 
private Q_SLOTS:
    void slotTimerExpired();
 
Q_SIGNALS:
    void timeout();
 
private:
    bool tryEmitOnTick(bool isFromTimer);
    bool tryEmitSignalSafely();
    void setDelayImpl(int delay);
 
private:
    QTimer *m_timer = 0;
    Mode m_mode = UNDEFINED;
    SlowHandlerMode m_slowHandlerMode = PRECISE_INTERVAL;
    bool m_signalsPending = false;
    QElapsedTimer m_lastEmittedTimer;
    int m_isEmitting = 0;
    int m_timeout = 0;
    std::function<bool()> m_idleCallback;
    int m_sanityIsStarting = 0;
};
 
#endif /* __KIS_SIGNAL_COMPRESSOR_H */