code: private static int snapOnly30s(int degrees, int forceHigherOrLower) {
          int stepSize = HOUR_VALUE_TO_DEGREES_STEP_SIZE;
          int floor = (degrees / stepSize) * stepSize;
          int ceiling = floor + stepSize;
          if (forceHigherOrLower == 1) {
              degrees = ceiling;
          } else if (forceHigherOrLower == -1) {
              if (degrees == floor) {
                  floor -= stepSize;
              }
              degrees = floor;
          } else {
              if ((degrees - floor) < (ceiling - degrees)) {
                  degrees = floor;
              } else {
                  degrees = ceiling;
              }
          }
          return degrees;
      }
docs: Returns mapping of any input degrees (0 to 360) to one of 12 visible output degrees (all
  multiples of 30), where the input will be "snapped" to the closest visible degrees.
  @param degrees The input degrees
  @param forceHigherOrLower The output may be forced to either the higher or lower step, or may
  be allowed to snap to whichever is closer. Use 1 to force strictly higher, -1 to force
  strictly lower, and 0 to snap to the closer one.
  @return output degrees, will be a multiple of 30