在Angular2中将封装设置为无设置背景

Question

I'm trying to set an image to the background of an entire page the following way:

app.component.html

<div [ngStyle]="{'background-image': 'url(' + somePhoto + ')'}">
  <h1>
    Hello, world
  </h1>
</div>

app.component.ts (note: encapsulation set to none)

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

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
  encapsulation: ViewEncapsulation.None
})
export class AppComponent implements OnInit {
  constructor() { }

  ngOnInit(): void {
    console.log('hello, world');
  }
}

app.component.css

body {
   background-repeat: no-repeat;
   background-size: cover;
   background-position: center center;
   background-attachment: fixed;
 }

The problem is, when using [ngStyle] the image only covers the header portion of the page.

If instead of ngStyle, I select the body directly with something like:

 document.body.style.backgroundImage = 'url(someimage.jpg)';

The image covers the entire page, which is what I want to happen. But I've been told selecting the body directly is bad practice.

How can I get [ngStyle] (or anything else) to create a background image that covers an entire page?

Thanks

Answer 1

You could cover the body with a div of your template, and fill it with the background image, as shown in this stackblitz :

app.component.html

<div class="outerDiv" [ngStyle]="{'background-image': 'url(' + somePhoto + ')'}">
    <div>
        <h1>
            Hello, world!
        </h1>
    </div>
</div>

app.component.css

.outerDiv {
    width: 100%;
    height: 100%;
    overflow: hidden;
    background-repeat: no-repeat;
    background-size: cover;
    background-position: center center;
    background-attachment: fixed;  
}

styles.css:

html,
body {
    width: 100%;
    height: 100%;
    padding: 0;
    margin: 0;
}

Note: I added an outer div to allow setting overflow: hidden . Without that style attribute, the default margin of the h1 element prevented the div from filling the top of the body (at least in Chrome on Windows).