Function GetRefreshRateFromXRandR

common/WindowInfo.cpp:163–243

#include <X11/Xlib.h>

static std::optional<float> GetRefreshRateFromXRandR(const WindowInfo& wi)
{
	Display* display = static_cast<Display*>(wi.display_connection);
	Window window = static_cast<Window>(reinterpret_cast<uintptr_t>(wi.window_handle));
	if (!display || !window)
		return std::nullopt;

	XRRScreenResources* res = XRRGetScreenResources(display, window);
	if (!res)
	{
		Console.Error("(GetRefreshRateFromXRandR) XRRGetScreenResources() failed");
		return std::nullopt;
	}

	ScopedGuard res_guard([res]() { XRRFreeScreenResources(res); });

	int num_monitors;
	XRRMonitorInfo* mi = XRRGetMonitors(display, window, True, &num_monitors);
	if (num_monitors < 0)
	{
		Console.Error("(GetRefreshRateFromXRandR) XRRGetMonitors() failed");
		return std::nullopt;
	}
	else if (num_monitors > 1)
	{
		Console.Warning("(GetRefreshRateFromXRandR) XRRGetMonitors() returned %d monitors, using first", num_monitors);
	}

	ScopedGuard mi_guard([mi]() { XRRFreeMonitors(mi); });
	if (mi->noutput <= 0)
	{
		Console.Error("(GetRefreshRateFromXRandR) Monitor has no outputs");
		return std::nullopt;
	}
	else if (mi->noutput > 1)
	{
		Console.Warning("(GetRefreshRateFromXRandR) Monitor has %d outputs, using first", mi->noutput);
	}

	XRROutputInfo* oi = XRRGetOutputInfo(display, res, mi->outputs[0]);
	if (!oi)
	{
		Console.Error("(GetRefreshRateFromXRandR) XRRGetOutputInfo() failed");
		return std::nullopt;
	}

	ScopedGuard oi_guard([oi]() { XRRFreeOutputInfo(oi); });

	XRRCrtcInfo* ci = XRRGetCrtcInfo(display, res, oi->crtc);
	if (!ci)
	{
		Console.Error("(GetRefreshRateFromXRandR) XRRGetCrtcInfo() failed");
		return std::nullopt;
	}

	ScopedGuard ci_guard([ci]() { XRRFreeCrtcInfo(ci); });

	XRRModeInfo* mode = nullptr;