Equal smoothing treatment

android/src/main/java/com/sensorworks/RNBarometer/RNBarometerModule.java

@@ -26,14 +26,19 @@
 
 @ReactModule(name = RNBarometerModule.NAME)
 public class RNBarometerModule extends ReactContextBaseJavaModule implements LifecycleEventListener, SensorEventListener {
+
   public static final String NAME = "RNBarometer";
-  private static final double kPressFilteringFactor = 0.3;
+
+  public static final int DEFAULT_INTERVAL_MS = 200;  //  5 Hz
+  public static final double DEFAULT_SMOOTHING_FACTOR = 0.7;
+
   private static final int ignoreSamples = 10;
   private final ReactApplicationContext reactContext;
   private final SensorManager mSensorManager;
   private final Sensor mPressureSensor;
   private boolean isRunning;
-  private int mIntervalMillis;
+  private int mIntervalMillis = DEFAULT_INTERVAL_MS;
+  private double mSmoothingFactor = DEFAULT_SMOOTHING_FACTOR;
   private long mLastSampleTime;
   private double mInitialAltitude;
   private double mRelativeAltitude;
@@ -55,7 +60,8 @@ public RNBarometerModule(ReactApplicationContext reactContext) {
     mLastSampleTime = 0;
     mRelativeAltitude = 0;
     mInitialAltitude = -1;
-    mIntervalMillis = 200; // 5Hz
+    mIntervalMillis = DEFAULT_INTERVAL_MS;
+    mSmoothingFactor = DEFAULT_SMOOTHING_FACTOR;
     isRunning = false;
   }
 
@@ -120,6 +126,23 @@ public void setLocalPressure(double pressurehPa) {
     mLocalPressurehPa = pressurehPa;
   }
 
+  @ReactMethod
+  // Sets smoothing factor [0 -1].
+  // Note: More smoothing means more latency before
+  // the smoothed value has "caught up with" current
+  // conditions.
+  public void setSmoothingFactor(double smoothingFactor) {
+    if (smoothingFactor >= 0 && smoothingFactor <= 1.0) {
+      mSmoothingFactor = smoothingFactor;
+    }
+  }
+
+  @ReactMethod
+  // Gets smoothing factor
+  public void getSmoothingFactor(Promise promise) {
+    promise.resolve(mSmoothingFactor);
+  }
+
   @ReactMethod
   // Starts observing pressure
   public void startObserving(Promise promise) {
@@ -155,8 +178,8 @@ public void onSensorChanged(SensorEvent sensorEvent) {
     long timeSinceLastUpdate = tempMs - mLastSampleTime;
     if (timeSinceLastUpdate >= mIntervalMillis) {
       double lastAltitudeASL = mAltitudeASL;
-      // Get the filtered raw pressure in millibar/hPa
-      mRawPressure = (sensorEvent.values[0] * kPressFilteringFactor + mRawPressure * (1.0 - kPressFilteringFactor));
+      // Get the smoothed raw pressure in millibar/hPa
+      mRawPressure = (sensorEvent.values[0] * (((double)1.0) - mSmoothingFactor) + mRawPressure * mSmoothingFactor);
       // Calculate standard atmosphere altitude in metres
       mAltitudeASL = getAltitude(SensorManager.PRESSURE_STANDARD_ATMOSPHERE, mRawPressure);
       // Calculate our vertical speed in metres per second

index.d.ts

@@ -0,0 +1,43 @@
+// Module d.ts file
+
+// Enables using module in typescript react-native projects,
+// with editor auto-complete and type-validation (in VS Code)
+
+// See:
+// Typescript docs:
+//   https://www.typescriptlang.org/docs/handbook/declaration-files/templates/module-d-ts.html
+// Typescript Playground, for automatic generation of .d.ts file from .js:
+//   https://www.typescriptlang.org/play?filetype=js&useJavaScript=true#code/Q
+// Simplest approach:
+// https://stackoverflow.com/a/51355583
+
+declare module "react-native-barometer";
+
+interface BarometerPayload {  // See module README for field descriptions
+  timestamp:number,
+  pressure:number,
+  altitudeASL:number,
+  altitude:number,
+  relativeAltitude:number,
+  verticalSpeed:number,
+};
+
+type BarometerWatchCallbackFn = (payload:BarometerPayload) => void;
+
+declare namespace Barometer {  // See module README for function descriptions
+  function isSupported(): Promise<boolean>;
+  function setInterval(interval: number): void;
+  function setLocalPressure(pressure: number): void;
+  function watch(success: BarometerWatchCallbackFn): number;
+  function clearWatch(watchID: any): void;
+  function stopObserving(): void;
+  function setSmoothingFactor(smoothingFactor:double): void;
+  function getSmoothingFactor(): Promise<double>;
+}
+
+export {
+  BarometerPayload,
+  BarometerWatchCallbackFn
+};
+
+export default Barometer;

index.js

@@ -73,6 +73,19 @@ const Barometer = {
   // Sets the local air pressure in hPA/Millibars
   setLocalPressure: function(pressure) {
     RNBarometer.setLocalPressure(pressure);
+  },
+
+  // Sets smoothingFactor, a value [0 - 1] that determines
+  // how much smoothing is applied to the raw value.
+  // Note: More smoothing means more latency before
+  // the smoothed value has "caught up with" current
+  // conditions.
+  setSmoothingFactor: function(smoothingFactor) {
+    RNBarometer.setSmoothingFactor(smoothingFactor);
+  },
+
+  getSmoothingFactor: async function() {
+    return await RNBarometer.getSmoothingFactor();
   }
 
 };

ios/RNBarometer.h

@@ -13,6 +13,7 @@
     double rawPressure;
     double altitudeASL;
     double altitude;
+    double smoothingFactor;
 }
 
 @end

ios/RNBarometer.m

@@ -8,6 +8,8 @@
 #import <React/RCTLog.h>
 
 const double STANDARD_ATMOSPHERE = 1013.25;
+const long DEFAULT_INTERVAL_MS = 0.7;  //  5 Hz
+const double DEFAULT_SMOOTHING_FACTOR = 0.7;
 
 @implementation RNBarometer
 
@@ -24,8 +26,9 @@ - (id) init {
     rawPressure = 0;
     altitudeASL = 0;
     lastSampleTime = 0;
-    intervalMillis = 200; // 5Hz
+    intervalMillis = DEFAULT_INTERVAL_MS;
     isRunning = false;
+    smoothingFactor = DEFAULT_SMOOTHING_FACTOR;
   }
   return self;
 }
@@ -62,6 +65,24 @@ + (BOOL)requiresMainQueueSetup
   localPressurehPa = pressurehPa;
 }
 
+// Sets smoothing factor [0 -1].
+// Note: More smoothing means more latency before
+// the smoothed value has "caught up with" current
+// conditions.
+RCT_EXPORT_METHOD(setSmoothingFactor:(double) smoothingFactor) {
+  if (smoothingFactor >= 0 && smoothingFactor <= 1.0) {
+    self->smoothingFactor = smoothingFactor;
+  }
+}
+
+// Get the smoothing factor
+RCT_EXPORT_METHOD(getSmoothingFactor,
+                  resolver:(RCTPromiseResolveBlock)resolve
+                  rejecter:(RCTPromiseRejectBlock)reject) {
+  return resolve(self->smoothingFactor);
+}
+
+
 // Starts observing pressure
 RCT_EXPORT_METHOD(startObserving) {
   if(!isRunning) {
@@ -71,7 +92,9 @@ + (BOOL)requiresMainQueueSetup
       if(timeSinceLastUpdate >= self->intervalMillis && altitudeData){
         double lastAltitudeASL = self->altitudeASL;
         // Get the raw pressure in millibar/hPa
-        self->rawPressure = altitudeData.pressure.doubleValue * 10.0; // the x10 converts to millibar
+        double newRawPressure = altitudeData.pressure.doubleValue * 10.0; // the x10 converts to millibar
+        // Apply any smoothing
+        self->rawPressure = (newRawPressure * (((double)1.0) - mSmoothingFactor) + self->rawPressure * mSmoothingFactor);
         // Calculate standard atmpsphere altitude in metres
         self->altitudeASL = getAltitude(STANDARD_ATMOSPHERE, self->rawPressure);
         // Calculate our vertical speed in metres per second
@@ -115,5 +138,6 @@ + (BOOL)requiresMainQueueSetup
   return 44330.0 * (1.0 - pow(p/p0, coef));
 }
 
+
 @end