Chris@1074: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
Chris@1074: 
Chris@1074: /*
Chris@1074:     Sonic Visualiser
Chris@1074:     An audio file viewer and annotation editor.
Chris@1074:     Centre for Digital Music, Queen Mary, University of London.
Chris@1074:     
Chris@1074:     This program is free software; you can redistribute it and/or
Chris@1074:     modify it under the terms of the GNU General Public License as
Chris@1074:     published by the Free Software Foundation; either version 2 of the
Chris@1074:     License, or (at your option) any later version.  See the file
Chris@1074:     COPYING included with this distribution for more information.
Chris@1074: */
Chris@1074: 
Chris@1074: #ifndef RENDER_TIMER_H
Chris@1074: #define RENDER_TIMER_H
Chris@1074: 
Chris@1074: #include <chrono>
Chris@1074: 
Chris@1074: class RenderTimer
Chris@1074: {
Chris@1074: public:
Chris@1074:     enum Type {
Chris@1266:         /// A normal rendering operation with normal responsiveness demands
Chris@1266:         FastRender,
Chris@1074: 
Chris@1266:         /// An operation that the user might accept being slower
Chris@1266:         SlowRender,
Chris@1074: 
Chris@1266:         /// An operation that should always complete, i.e. as if there
Chris@1266:         /// were no RenderTimer in use, but without having to change
Chris@1266:         /// client code structurally
Chris@1266:         NoTimeout
Chris@1074:     };
Chris@1074:     
Chris@1074:     /**
Chris@1074:      * Create a new RenderTimer and start timing. Make one of these
Chris@1074:      * before rendering, and then call outOfTime() regularly during
Chris@1074:      * rendering. If outOfTime() returns true, abandon rendering!  and
Chris@1074:      * schedule the rest for after some user responsiveness has
Chris@1074:      * happened.
Chris@1074:      */
Chris@1074:     RenderTimer(Type t) :
Chris@1266:         m_start(std::chrono::steady_clock::now()),
Chris@1266:         m_haveLimits(true),
Chris@1266:         m_minFraction(0.1),
Chris@1266:         m_softLimit(0.1),
Chris@1266:         m_hardLimit(0.2),
Chris@1266:         m_softLimitOverridden(false) {
Chris@1074: 
Chris@1266:         if (t == NoTimeout) {
Chris@1266:             m_haveLimits = false;
Chris@1266:         } else if (t == SlowRender) {
Chris@1266:             m_softLimit = 0.2;
Chris@1266:             m_hardLimit = 0.4;
Chris@1266:         }
Chris@1074:     }
Chris@1074: 
Chris@1074: 
Chris@1074:     /**
Chris@1074:      * Return true if we have run out of time and should suspend
Chris@1074:      * rendering and handle user events instead. Call this regularly
Chris@1074:      * during rendering work: fractionComplete should be an estimate
Chris@1074:      * of how much of the work has been done as of this call, as a
Chris@1074:      * number between 0.0 (none of it) and 1.0 (all of it).
Chris@1074:      */
Chris@1074:     bool outOfTime(double fractionComplete) {
Chris@1074: 
Chris@1266:         if (!m_haveLimits || fractionComplete < m_minFraction) {
Chris@1266:             return false;
Chris@1266:         }
Chris@1266:         
Chris@1266:         auto t = std::chrono::steady_clock::now();
Chris@1266:         double elapsed = std::chrono::duration<double>(t - m_start).count();
Chris@1266:         
Chris@1266:         if (elapsed > m_hardLimit) {
Chris@1266:             return true;
Chris@1266:         } else if (!m_softLimitOverridden && elapsed > m_softLimit) {
Chris@1266:             if (fractionComplete > 0.6) {
Chris@1266:                 // If we're significantly more than half way by the
Chris@1266:                 // time we reach the soft limit, ignore it (though
Chris@1266:                 // always respect the hard limit, above). Otherwise
Chris@1266:                 // respect the soft limit and report out of time now.
Chris@1266:                 m_softLimitOverridden = true;
Chris@1266:             } else {
Chris@1266:                 return true;
Chris@1266:             }
Chris@1266:         }
Chris@1074: 
Chris@1266:         return false;
Chris@1074:     }
Chris@1074: 
Chris@1221:     double secondsPerItem(int itemsRendered) const {
Chris@1221: 
Chris@1221:         if (itemsRendered == 0) return 0.0;
Chris@1221: 
Chris@1266:         auto t = std::chrono::steady_clock::now();
Chris@1266:         double elapsed = std::chrono::duration<double>(t - m_start).count();
Chris@1221: 
Chris@1221:         return elapsed / itemsRendered;
Chris@1221:     }
Chris@1221: 
Chris@1074: private:
Chris@1074:     std::chrono::time_point<std::chrono::steady_clock> m_start;
Chris@1074:     bool m_haveLimits;
Chris@1221:     double m_minFraction; // proportion, 0.0 -> 1.0
Chris@1221:     double m_softLimit; // seconds
Chris@1221:     double m_hardLimit; // seconds
Chris@1074:     bool m_softLimitOverridden;
Chris@1074: };
Chris@1074: 
Chris@1074: #endif