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/*
This file is part of Warzone 2100.
Copyright (C) 2011-2019 Warzone 2100 Project
Warzone 2100 is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
Warzone 2100 is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with Warzone 2100; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "lib/framework/frame.h"
#include "gfx_api_null_sdl.h"
#include <thread>
#include <chrono>
#define NULLBACKEND_VSYNC_MAX_FPS 120
const auto minFrameDuration = std::chrono::nanoseconds(1000000000) / NULLBACKEND_VSYNC_MAX_FPS;
sdl_Null_Impl::sdl_Null_Impl()
{
// no-op
}
void sdl_Null_Impl::swapWindow()
{
// Handle throttling / sleeping
switch (swapMode)
{
case gfx_api::context::swap_interval_mode::vsync:
// fall-through
case gfx_api::context::swap_interval_mode::adaptive_vsync:
{
// simulate pseudo-vsync - try to restrict to NULLBACKEND_VSYNC_FPS "frames" per sec
auto swapEndTime = std::chrono::steady_clock::now();
auto minSwapEndTime = lastSwapEndTime + minFrameDuration;
if (swapEndTime < minSwapEndTime)
{
std::this_thread::sleep_until(minSwapEndTime);
swapEndTime = minSwapEndTime;
}
lastSwapEndTime = swapEndTime;
break;
}
case gfx_api::context::swap_interval_mode::immediate:
break;
}
}
bool sdl_Null_Impl::setSwapInterval(gfx_api::context::swap_interval_mode mode)
{
swapMode = mode;
return true;
}
gfx_api::context::swap_interval_mode sdl_Null_Impl::getSwapInterval() const
{
return swapMode;
}
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