gistfile1.txt

 public static class ScreenSettings
    {
        public static void MakeScreenOn()
        {
            int ret = DevicePowerRequestLock(1, 0); // type : CPU:0, DisplayNormal:1, DisplayDim:2
            //if (ret != 0)
            //{
            //    Exception exp;
            //    switch (ret)
            //    {
            //        case -22:// invalid parameter
            //            exp = new InvalidOperationException("[device_power_request_lock] invalid parameter.");
            //            break;
            //        case -13: // permission denied
            //            exp = new UnauthorizedAccessException("[device_power_request_lock] permission denied.");
            //            break;
            //        case -0x01140000 | 0x01: // operation failed
            //            exp = new InvalidOperationException("[device_power_request_lock] Operation Failed");
            //            break;
            //        default:
            //            exp = new InvalidOperationException("[device_power_request_lock] The unknown error occurs.");
            //            break;
            //    }
            //    throw exp;
            //}
        }

        public static void MakeScreenOff()
        {
            int ret = DevicePowerReleaseLock(1);    // type : CPU:0, DisplayNormal:1, DisplayDim:2
            //if (ret != 0)
            //{
            //    Exception exp;
            //    switch (ret)
            //    {
            //        case -22:// invalid parameter
            //            exp = new InvalidOperationException("[device_power_release_lock] invalid parameter.");
            //            break;
            //        case -13: // permission denied
            //            exp = new UnauthorizedAccessException("[device_power_release_lock] permission denied.");
            //            break;
            //        case -0x01140000 | 0x01: // operation failed
            //            exp = new InvalidOperationException("[device_power_release_lock] Operation Failed");
            //            break;
            //        default:
            //            exp = new InvalidOperationException("[device_power_release_lock] The unknown error occurs.");
            //            break;
            //    }
            //    throw exp;
            //}
        }

        [DllImport("libcapi-system-device.so.0", EntryPoint = "device_power_request_lock", CallingConvention = CallingConvention.Cdecl)]
        internal static extern int DevicePowerRequestLock(int type, int timeout_ms);

        [DllImport("libcapi-system-device.so.0", EntryPoint = "device_power_release_lock", CallingConvention = CallingConvention.Cdecl)]
        internal static extern int DevicePowerReleaseLock(int type);
    }