How to use multiple instances of same component in Angular 6?

Question

I have created a component with selector 'app-circle'. The HTML of the component contains an SVG for a circle.

What I want is - to use multiple 'app-circle' in my main HTML to draw multiple circles with different attributes (say, color). But I cannot seem to be able to do this. Basically, my intention was to re-use 'app-circle' as multiple objects.

(Please forgive me for being naive; I am new to angular & web development and my experience is mainly in C#, which might be the reason for me to find difficulty in wrapping around angular/web concepts and way of working)

Here is the code: -

main.html

<div class="diagram-wrapper">
  <app-circle></app-circle>
  <app-circle></app-circle>
</div>

circle.component.html

<svg class="range" height="100" width="100">
  <circle class="circle" cx="50" cy="50" r="40" stroke="black" stroke-width="3" fill="red" />
</svg>

circle.component.ts

import { Component, OnInit, AfterViewInit } from '@angular/core';

@Component({
            selector: 'app-circle',
            templateUrl: './circle.component.html',
            styleUrls: ['./circle.component.scss']
          })
export class CircleComponent implements OnInit, AfterViewInit {

constructor() { }

ngOnInit() { }

ngAfterViewInit() {
 // Circle logic (fill colors, etc.)
}

Answer 1

Following the suggestion in the comments, I added the @Input to a fork of your stackblitz here: https://stackblitz.com/edit/angular-jppwhz?file=src%2Fapp%2Fapp.component.html

The HTML uses binding to bind the desired color:

<div class="diagram-wrapper">
  <app-circle color='blue'></app-circle>
  <app-circle color='green'></app-circle>
</div>

I hard-coded in the color values, but they could be provided as properties from the associated component.

The circle code then looks like this:

import { Component, OnInit, AfterViewInit, Input, ViewChild, ElementRef } from '@angular/core';

@Component({
  selector: 'app-circle',
  templateUrl: './circle.component.html',
  styleUrls: ['./circle.component.scss']
})
export class CircleComponent implements OnInit, AfterViewInit {
  @Input() color;
  @ViewChild('circle') circleEle: ElementRef;

  constructor() { }

  ngOnInit() { }

  ngAfterViewInit() {
    // Circle logic (fill colors, etc.)
    console.log(this.circleEle);
    if (this.circleEle) {
      this.circleEle.nativeElement.style.fill = this.color;
    }
  }
}

Hope this helps.