73 lines
2.4 KiB
C++
73 lines
2.4 KiB
C++
/* ScummVM - Graphic Adventure Engine
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*
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* ScummVM is the legal property of its developers, whose names
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* are too numerous to list here. Please refer to the COPYRIGHT
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* file distributed with this source distribution.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#include "graphics/framelimiter.h"
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#include "common/util.h"
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namespace Graphics {
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FrameLimiter::FrameLimiter(OSystem *system, const uint framerate, const bool deferToVsync) :
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_system(system),
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_deferToVsync(deferToVsync) {
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initialize(framerate);
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}
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void FrameLimiter::initialize() {
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_enabled = (_frameLimit != 0) && !(_deferToVsync && _system->getFeatureState(OSystem::kFeatureVSync));
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_frameDuration = _frameLimit;
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}
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void FrameLimiter::initialize(const uint framerate) {
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_frameLimit = (framerate > 0) ? 1000.0f / CLIP<uint>(framerate, 1, 120) : 0;
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initialize();
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}
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uint FrameLimiter::startFrame() {
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_now = _system->getMillis();
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if (_frameStart != 0) {
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_frameDuration = _now - _frameStart;
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_drawDuration = _now - _drawStart;
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}
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_frameStart = _now;
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return _frameDuration;
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}
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bool FrameLimiter::delayBeforeSwap() {
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_now = _system->getMillis();
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_loopDuration = _now - _frameStart;
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if (_enabled) {
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//_delay = _frameLimit - _loopDuration; // Original functionality, will tend to undershoot target framerate slightly due to finite screen.update() time.
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_delay = _frameLimit - (_now - _drawStart); // Ensure that EXACTLY the specified frame duration has elapsed since last screen.update() was called.
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if (_delay > 0)
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_system->delayMillis(_delay);
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}
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_drawStart = _system->getMillis();
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return (_delay < 0); // Check if frame is late
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}
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void FrameLimiter::pause(bool pause) {
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if (!pause)
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_frameStart = 0; // Ensure that the frame duration value is consistent when resuming
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}
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} // End of namespace Graphics
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