How to use Angular material spinner in Ionic angular project.

Angular Material provides a built-in loading spinner component that can be used to display a loading animation while data is being fetched or processed. To use the Angular Material loading spinner in an Ionic app, you can follow these steps:

Install the necessary packages: First, you need to install the Angular Material components and dependencies in your Ionic app. You can do this by running the following command:

npm install @angular/material @angular/cdk @angular/animations

Import the modules: Once you have installed the packages, you need to import the necessary Angular Material modules in your app.module.ts file. For example, to use the loading spinner component, you can import the MatProgressSpinnerModule as follows:

import { NgModule } from '@angular/core';
import { MatProgressSpinnerModule } from '@angular/material/progress-spinner';

@NgModule({
  imports: [
    // other imports
    MatProgressSpinnerModule
  ],
  // other declarations
})
export class AppModule { }

Add the loading spinner to your template: Once you have imported the MatProgressSpinnerModule, you can use the MatProgressSpinner component in your template. For example, you can add the following code to display a loading spinner:

<ion-content>

  <div class="loading-container" *ngIf="loading">

    <mat-progress-spinner mode="indeterminate"></mat-progress-spinner>

  </div>

  

</ion-content>

In the above code, we have added a div with a class of "loading-container" that is only shown when the "loading" variable is true. Inside the div, we have added the MatProgressSpinner component with a mode of "indeterminate" to display a loading animation.

Add the loading variable to your component: In order to toggle the display of the loading spinner, you need to define a boolean variable in your component to track the loading state. For example:

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

@Component({
  selector: 'app-my-component',
  templateUrl: './my-component.component.html',
  styleUrls: ['./my-component.component.css']
})
export class MyComponent implements OnInit {
  loading = true; // set the initial loading state

  constructor() { }

  ngOnInit(): void {
    // simulate a delay
    setTimeout(() => {
      this.loading = false;
    }, 3000);
  }
}

In this example, we have defined a "loading" variable in our component and set its initial state to true. We also have a ngOnInit method that simulates a delay of 3 seconds before setting the loading variable to false.

Style the loading spinner: You can customize the appearance of the loading spinner by adding CSS styles to the MatProgressSpinner element. For example, you can change the size of the spinner by adding the following styles to your CSS file:

.mat-progress-spinner {

  width: 50px;

  height: 50px;

}

This will set the width and height of the spinner to 50 pixels.

Add a backdrop to the loading spinner (optional): By default, the loading spinner will be displayed on a transparent background. However, you can add a backdrop to the spinner to make it more prominent and prevent users from interacting with the underlying content while the spinner is displayed.

To add a backdrop to the loading spinner, you can wrap the MatProgressSpinner element inside a MatSpinner overlay element. For example:

<ion-content>
  <div class="loading-container" *ngIf="loading">
    <mat-spinner class="overlay"></mat-spinner>
  </div>
  
</ion-content>

In this example, we have wrapped the MatProgressSpinner element inside a MatSpinner element and added a "overlay" class to it. We can then add CSS styles to the overlay class to position the spinner in the center of the screen and add a semi-transparent background. For example:

.overlay {

  position: absolute;

  top: 50%;

  left: 50%;

  transform: translate(-50%, -50%);

  background-color: rgba(0, 0, 0, 0.5);

  z-index: 9999;

}

This will position the spinner in the center of the screen and add a semi-transparent black background to it.

By following these steps and customizing the loading spinner as needed, you can provide a better user experience for your Ionic app users by displaying a loading animation during long-running operations.