first commit

src/app/indicator/indicator.component.html

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+<div class="container">
+  <mat-icon *ngIf='featureFinderService.hasDirection$ | async' aria-hidden="false"
+    matTooltip="Direction to interesting stuff..."
+    [ngStyle]="{'transform':'rotate(' + (featureFinderService.direction$ | async) + 'deg)'}">
+    north
+  </mat-icon>
+
+  <div *ngIf='distance'>
+    {{ distance }} m
+  </div>
+
+  <mat-icon class="north"
+    matTooltip="Direction of north"
+    [ngStyle]="{'transform':'rotate(' + (featureFinderService.orientation$ | async) + 'deg)'}">
+    north
+  </mat-icon>
+<div>

src/app/indicator/indicator.component.scss

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+.container {
+  display: flex;
+  flex-direction: row;
+  align-items: center;
+  font-size: 1.5em;
+}

src/app/indicator/indicator.component.spec.ts

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+import { ComponentFixture, TestBed } from '@angular/core/testing';
+
+import { IndicatorComponent } from './indicator.component';
+
+describe('IndicatorComponent', () => {
+  let component: IndicatorComponent;
+  let fixture: ComponentFixture<IndicatorComponent>;
+
+  beforeEach(async () => {
+    await TestBed.configureTestingModule({
+      declarations: [ IndicatorComponent ]
+    })
+    .compileComponents();
+  });
+
+  beforeEach(() => {
+    fixture = TestBed.createComponent(IndicatorComponent);
+    component = fixture.componentInstance;
+    fixture.detectChanges();
+  });
+
+  it('should create', () => {
+    expect(component).toBeTruthy();
+  });
+});

src/app/indicator/indicator.component.ts

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+import { Component, OnInit,
+  ChangeDetectorRef, ChangeDetectionStrategy } from '@angular/core'
+import { Observable, BehaviorSubject } from 'rxjs'
+import { map } from 'rxjs/operators'
+
+import { ActionService } from '../action.service'
+import { FeatureFinderService } from '../feature-finder.service'
+
+@Component({
+  selector: 'app-indicator',
+  templateUrl: './indicator.component.html',
+  styleUrls: ['./indicator.component.scss'],
+  changeDetection: ChangeDetectionStrategy.OnPush,
+})
+export class IndicatorComponent implements OnInit {
+
+  constructor(
+    public actionService: ActionService,
+    public featureFinderService: FeatureFinderService,
+    private cdr: ChangeDetectorRef,
+  ) { }
+
+  distance: number
+
+  ngOnInit(): void {
+    this.featureFinderService.distance$.subscribe(
+      dist => {
+        this.distance = Math.round(dist)
+        this.cdr.markForCheck()
+      }
+    )
+
+    this.featureFinderService.direction$.subscribe(
+      _ => this.cdr.markForCheck()
+    )
+
+    this.featureFinderService.orientation$.subscribe(
+      _ => this.cdr.markForCheck()
+    )
+  }
+}