52 lines
1.5 KiB
TypeScript
52 lines
1.5 KiB
TypeScript
import { Injectable } from '@angular/core';
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import { Observer, Observable } from 'rxjs';
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@Injectable()
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export class DeviceOrientationService {
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compassHeading(alpha, beta, gamma):number {
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// Convert degrees to radians
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const alphaRad = alpha * (Math.PI / 180);
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const betaRad = beta * (Math.PI / 180);
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const gammaRad = gamma * (Math.PI / 180);
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// Calculate equation components
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const cA = Math.cos(alphaRad);
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const sA = Math.sin(alphaRad);
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const cB = Math.cos(betaRad);
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const sB = Math.sin(betaRad);
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const cG = Math.cos(gammaRad);
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const sG = Math.sin(gammaRad);
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// Calculate A, B, C rotation components
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const rA = - cA * sG - sA * sB * cG;
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const rB = - sA * sG + cA * sB * cG;
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const rC = - cB * cG;
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// Calculate compass heading
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let compassHeading = Math.atan(rA / rB);
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// Convert from half unit circle to whole unit circle
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if(rB < 0) {
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compassHeading += Math.PI;
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}else if(rA < 0) {
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compassHeading += 2 * Math.PI;
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}
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return compassHeading * (180/Math.PI);
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}
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getCurrentCompassHeading(): Observable<number> {
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return Observable.create((observer: Observer<number>) => {
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window.addEventListener("deviceorientation", (event:DeviceOrientationEvent)=>{
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const heading = this.compassHeading(event.alpha,event.beta,event.gamma);
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if(!Number.isNaN(heading)) {
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observer.next(heading);
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}
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} );
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});
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}
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}
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