Angular 2 Material Progress Spinner: display as overlay

I was able to get this to work with Angular 13 following Tomek's solution however I had to add: encapsulation: ViewEncapsulation.None to my @Component declaration that is being used as a dialog:

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

@Component({
  selector: 'app-progress-spinner-dialog',
  templateUrl: './progress-spinner-dialog.component.html',
  styleUrls: ['./progress-spinner-dialog.component.css'],
  // this needed to override the mat-dialog-container CSS class
  encapsulation: ViewEncapsulation.None
})

Without this reference to ViewEncapsulation.None I was not able to get the CSS override to work. I found this great hint here: Learn Angular 11 MatDialog Basics

I was inspired by: Overriding Angular Material Size and Styling of md-dialog-container

I solved it like this:

Create a New Component

Create a new component ProgressSpinnerDialogComponent

The content of progress-spinner-dialog.component.html:

<mat-spinner></mat-spinner>

The content of progress-spinner-dialog.component.ts:

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

@Component({
  selector: 'app-progress-spinner-dialog',
  templateUrl: './progress-spinner-dialog.component.html',
  styleUrls: ['./progress-spinner-dialog.component.css']
})
export class ProgressSpinnerDialogComponent implements OnInit {

  constructor() { }

  ngOnInit() {
  }

}

Add a Style

In styles.css add:

.transparent .mat-dialog-container {
    box-shadow: none;
    background: rgba(0, 0, 0, 0.0);
}

Use the Component

Here an example usage of the progress spinner:

import { Component, OnInit } from '@angular/core';
import { MatDialog, MatDialogRef } from "@angular/material/dialog";
import { Observable } from "rxjs";
import { ProgressSpinnerDialogComponent } from "/path/to/progress-spinner-dialog.component";

@Component({
  selector: 'app-use-progress-spinner-component',
  templateUrl: './use-progress-spinner-component.html',
  styleUrls: ['./use-progress-spinner-component.css']
})
export class UseProgressSpinnerComponent implements OnInit {

  constructor(
    private dialog: MatDialog
  ) {
    let observable = new Observable(this.myObservable);
    this.showProgressSpinnerUntilExecuted(observable);
  }

  ngOnInit() {
  }

  myObservable(observer) {
    setTimeout(() => {
      observer.next("done waiting for 5 sec");
      observer.complete();
    }, 5000);
  }

  showProgressSpinnerUntilExecuted(observable: Observable<Object>) {
    let dialogRef: MatDialogRef<ProgressSpinnerDialogComponent> = this.dialog.open(ProgressSpinnerDialogComponent, {
      panelClass: 'transparent',
      disableClose: true
    });
    let subscription = observable.subscribe(
      (response: any) => {
        subscription.unsubscribe();
        //handle response
        console.log(response);
        dialogRef.close();
      },
      (error) => {
        subscription.unsubscribe();
        //handle error
        dialogRef.close();
      }
    );
  }
}

Add it to the app.module

 declarations: [...,ProgressSpinnerDialogComponent,...],
 entryComponents: [ProgressSpinnerDialogComponent],

Use the below code to achieve the opaque:

HTML

<div style="height: 800px" [class.hide]="show">
   <button class="btn btn-success" (click)="showSpinner()">Show spinner</button>
</div>
<app-spinner [show]="show" [size]="150"></app-spinner>

COMPONENT

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

@Component({
    selector: 'app-spinner',
    template: `
      <i aria-hidden="true" class="fa fa-spinner fa-spin" [style.font-size.px]="size" *ngIf="show"></i>
    `
})
export class SpinnerComponent {
  @Input() size = 50;
  @Input() show = false;
  
  showSpinner() {
    this.show = true;
  }
}

CSS

.hide {
  opacity: 0;
}

LIVE DEMO

Based on A bit different approach: Two components, first to open the dialog, second is the dialog. In the component you want to show the spinner just add:

<app-dialog-spinner *ngIf="progressSpinner"></app-dialog-spinner>

And control the *ngIf in your logic. Above is all you need to call the spinner so the component stays nice and clean.

Dialog spinner component:

import { Component, OnInit, OnDestroy } from '@angular/core';
import { MatDialog, MatDialogRef } from '@angular/material';

// Requires a transparent css (panel)id in a parent stylesheet e.g.:
// #DialogSpinnerComponent {
//   box-shadow: none !important;
//   background: transparent !important;
// }

@Component({
  selector: 'app-do-not-use',
  template: `<mat-spinner></mat-spinner>`,
  styles: []
})
export class DialogSpinnerDialogComponent { }

@Component({
  selector: 'app-dialog-spinner',
  template: ``,
  styles: []
})
export class DialogSpinnerComponent implements OnInit, OnDestroy {

  private dialog: MatDialogRef<DialogSpinnerDialogComponent>;

  constructor(
    private matDialog: MatDialog,
  ) { }

  ngOnInit() {
    setTimeout(() => {
      this.dialog = this.matDialog.open(DialogSpinnerDialogComponent, { id: 'DialogSpinnerComponent', disableClose: true });
    });
  }
  ngOnDestroy() {
    setTimeout(() => {
      this.dialog.close();
    });
  }

}

Declare the components in your module and of course register DialogSpinnerDialogComponent in your entryComponents. Add the css properties to a parent stylesheet. This can probably be improved but I'm a bit pressed for time.