Differential D8538 Diff 21615 libs/global/kis_relaxed_timer.h

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libs/global/kis_relaxed_timer.h

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		1		/*
		2		* Copyright (c) 2017 Bernhard Liebl <poke1024@gmx.de>
		3		*
		4		* This program is free software; you can redistribute it and/or modify
		5		* it under the terms of the GNU General Public License as published by
		6		* the Free Software Foundation; either version 2 of the License, or
		7		* (at your option) any later version.
		8		*
		9		* This program is distributed in the hope that it will be useful,
		10		* but WITHOUT ANY WARRANTY; without even the implied warranty of
		11		* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
		12		* GNU General Public License for more details.
		13		*
		14		* You should have received a copy of the GNU General Public License
		15		* along with this program; if not, write to the Free Software
		16		* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
		17		*/
		18
		19		#ifndef __KIS_RELAXED_TIMER_H
		20		#define __KIS_RELAXED_TIMER_H
		21
		22		#include <QObject>
		23		#include <QBasicTimer>
		24		#include <QElapsedTimer>
		25
		26		#include "kritaglobal_export.h"
		27
		28		/**
		29		* A timer using an interface like QTimer that relaxes the given interval callback
		30		* time guarantees and minimizes internal timer restarts by keeping one long-running
		31		* repeating timer.
		32		*
		33		* Users can use this just like a QTimer. The difference is that KisRelaxedTimer will
		34		* relax the callback guarantee time as follows: timeouts will never happen earlier
		35		* than \p interval ms, but may well happen only after 2 * \p interval ms (whereas
		36		* QTimer guarantees a fixed interval of \p interval ms).
		37		*
		38		* The rationale for using this is that stopping and starting timers can produce a
		39		* measurable performance overhead. KisRelaxedTimer removes that overhead.
		40		*/
		41		class KRITAGLOBAL_EXPORT KisRelaxedTimer : public QObject
		42		{
		43		Q_OBJECT
		44
		45		public:
		46		KisRelaxedTimer(QObject *parent = nullptr);
		47
		48		void start();
		49
		50		inline void stop() {
		51		m_emitOnTimeTick = 0;
		52		}
		53
		54		void setInterval(int interval);
		55		void setSingleShot(bool singleShot);
		56
		57		inline bool isActive() const {
		58		return m_emitOnTimeTick >= m_nextTimerTickSeqNo;
		59		}
		60
		61		int remainingTime() const;
		62
		63		Q_SIGNALS:
		64		void timeout();
		65
		66		protected:
		67		void timerEvent(QTimerEvent *event) override;
		68
		69		private:
		70		int m_interval;
		71		bool m_singleShot;
		72
		73		QBasicTimer m_timer;
		74		qint64 m_nextTimerTickSeqNo;
		75		qint64 m_emitOnTimeTick;
		76
		77		QElapsedTimer m_elapsed;
		78
		79		protected:
		80		class IsEmitting {
		81		public:
		82		IsEmitting(KisRelaxedTimer &timer) : m_timer(timer) {
		83		timer.m_isEmitting = true;
		84		}
		85
		86		~IsEmitting() {
		87		m_timer.m_isEmitting = false;
		88		}
		89
		90		private:
		91		KisRelaxedTimer &m_timer;
		92		};
		93
		94		friend class IsEmitting;
		95
		96		bool m_isEmitting;
		97		};
		98
		99		#endif /* __KIS_RELAXED_TIMER_H */