Function GetRefreshRate

Source/DisplayConfig.cpp:49–88

double GetRefreshRate(const wchar_t* displayName)
{
	UINT32 num_paths;
	UINT32 num_modes;
	std::vector<DISPLAYCONFIG_PATH_INFO> paths;
	std::vector<DISPLAYCONFIG_MODE_INFO> modes;
	LONG res;

	// The display configuration could change between the call to
	// GetDisplayConfigBufferSizes and the call to QueryDisplayConfig, so call
	// them in a loop until the correct buffer size is chosen
	do {
		res = GetDisplayConfigBufferSizes(QDC_ONLY_ACTIVE_PATHS, &num_paths, &num_modes);
		if (res == ERROR_SUCCESS) {
			paths.resize(num_paths);
			modes.resize(num_modes);
			res = QueryDisplayConfig(QDC_ONLY_ACTIVE_PATHS, &num_paths, paths.data(), &num_modes, modes.data(), nullptr);
		}
	} while (res == ERROR_INSUFFICIENT_BUFFER);

	if (res == ERROR_SUCCESS) {
		// num_paths and num_modes could decrease in a loop
		paths.resize(num_paths);
		modes.resize(num_modes);

		for (const auto& path : paths) {
			// Send a GET_SOURCE_NAME request
			DISPLAYCONFIG_SOURCE_DEVICE_NAME source = {
				{DISPLAYCONFIG_DEVICE_INFO_GET_SOURCE_NAME, sizeof(source), path.sourceInfo.adapterId, path.sourceInfo.id}, {},
			};
			if (DisplayConfigGetDeviceInfo(&source.header) == ERROR_SUCCESS) {
				if (wcscmp(displayName, source.viewGdiDeviceName) == 0) {
					return get_refresh_rate(path, modes.data());
				}
			}
		}
	}

	return 0.0;
}

static bool is_valid_refresh_rate(const DISPLAYCONFIG_RATIONAL& rr)
{