docs: update doc for gravity API and example to get raw device acceleration (react-native-sensors#400)

Author: Ehsan0Hejazi

.all-contributorsrc

@@ -325,6 +325,16 @@
       "contributions": [
         "code"
       ]
+    },
+    {
+      "login": "Ehsan0Hejazi",
+      "name": "Ehsan Hejazi",
+      "avatar_url": "https://avatars.githubusercontent.com/u/70890584?v=4",
+      "profile": "https://github.com/Ehsan0Hejazi",
+      "contributions": [
+        "code",
+        "doc"
+      ]
     }
   ],
   "repoType": "github"

docs/API.md

@@ -18,6 +18,15 @@ const subscription = accelerometer.subscribe(({ x, y, z, timestamp }) => console
 
 It might be interesting to note that the gravity of the earth is not removed from the sensoric values.
 Dependening on the position of the phone you will need to substract this from the values if you are interested in the raw values.
+See example : [device acceleration](https://react-native-sensors.github.io/docs/Usage.html#Raw-device-acceleration)
+
+## gravity: Observable<{x: number, y: number, z: number, timestamp: string}>
+
+```js
+import { gravity } from "react-native-sensors";
+
+const subscription = gravity.subscribe(({ x, y, z, timestamp }) => console.log({ x, y, z, timestamp }));
+```
 
 ## gyroscope: Observable<{x: number, y: number, z: number, timestamp: string}>
 

docs/Usage.md

@@ -6,6 +6,9 @@ sidebar_label: General
 
 You can access your sensor data through a [RxJS Observable](http://reactivex.io/rxjs/class/es6/Observable.js~Observable.html). This way you have the maximum of control over your data stream. You can add the values up, filter them, only react if a certain value is reached: You have the choice. Here is a small example showing the relatively small API interface. If you would like to learn more, please see the [API specification](/docs/API.html).
 
+
+## Device speed
+
 ```javascript
 import { accelerometer, gyroscope, setUpdateIntervalForType, SensorTypes } from "react-native-sensors";
 import { map, filter } from "rxjs/operators";
@@ -29,3 +32,36 @@ setTimeout(() => {
   subscription.unsubscribe();
 }, 1000);
 ```
+
+## Raw device acceleration
+
+You can get user raw acceleration which is calculated with (accelerometer - gravity) formula, to achieve this you can use RxJs combineLatest
+
+```javascript
+import { accelerometer, gravity, setUpdateIntervalForType, SensorTypes } from "react-native-sensors";
+import { combineLatest } from "rxjs";
+import { map } from 'rxjs/operators';
+
+const interval = 100;
+
+setUpdateIntervalForType(SensorTypes.accelerometer, interval);
+setUpdateIntervalForType(SensorTypes.gravity, interval);
+
+const userAccelerationStream = combineLatest(accelerometer, gravity).pipe(
+  map(([accelerometerValue, gravityValue]) => ({
+    accelerometer: accelerometerValue,
+    gravity: gravityValue,
+  }))
+)
+
+const subscription = userAccelerationStream.subscribe(event => console.log(
+  'x:', event.accelerometer.x - event.gravity.x,
+  'y:', event.accelerometer.y - event.gravity.y,
+  'z:', event.accelerometer.z - event.gravity.z,
+));
+
+setTimeout(() => {
+  subscription.unsubscribe();
+}, 1000);
+```
+