Implement copassheading

projects/common-map/src/fm-map/services/device-orientation.service.ts

@@ -5,19 +5,43 @@ import { Observer, Observable } from 'rxjs';
 @Injectable()
 export class DeviceOrientationService {
 
-   /**
-   * Tries HTML5 geolocation.
-   *
-   * Wraps the Geolocation API into an observable.
-   *
-   * @return An observable of Bearing
-   */
-  getCurrentBearing(): Observable<number> {
-    return Observable.create((observer: Observer<number>) => {             
-        let sensor = new Magnetometer();
-        sensor.onreading= (ev:Event) => {
-             observer.next(Math.atan2(sensor.y, sensor.x) * (180 / Math.PI));
-        };
+  compassHeading(alpha, beta, gamma):number {
+
+    // Convert degrees to radians
+    var alphaRad = alpha * (Math.PI / 180);
+    var betaRad = beta * (Math.PI / 180);
+    var gammaRad = gamma * (Math.PI / 180);
+  
+    // Calculate equation components
+    var cA = Math.cos(alphaRad);
+    var sA = Math.sin(alphaRad);
+    var cB = Math.cos(betaRad);
+    var sB = Math.sin(betaRad);
+    var cG = Math.cos(gammaRad);
+    var sG = Math.sin(gammaRad);
+  
+    // Calculate A, B, C rotation components
+    var rA = - cA * sG - sA * sB * cG;
+    var rB = - sA * sG + cA * sB * cG;
+    var rC = - cB * cG;
+  
+    // Calculate compass heading
+    var compassHeading = Math.atan(rA / rB);
+  
+    // Convert from half unit circle to whole unit circle
+    if(rB < 0) {
+      compassHeading += Math.PI;
+    }else if(rA < 0) {
+      compassHeading += 2 * Math.PI;
+    }
+    return compassHeading * (180/Math.PI);
+  }
+
+  getCurrentCompassHeading(): Observable<number> {
+    return Observable.create((observer: Observer<number>) => {  
+        window.addEventListener("deviceorientation", (event:DeviceOrientationEvent)=>{
+          observer.next(this.compassHeading(event.alpha,event.beta,event.gamma));
+        } );
     });
   }