Angular 2中背景图像URL的属性属性绑定 [英] Attribute property binding for background-image url in Angular 2

问题描述

我一直在努力寻找在许多 Angular 2 组件中动态更改background-image属性的最佳方法.

I have been struggling to figure out the best way to dynamically change the background-image attribute in a number of Angular 2 components.

在下面的示例中，我尝试使用[ngStyle]指令将div的background-image设置为@Input值:

In the following example, I am attempting to set the background-image of a div to an @Input value using [ngStyle] directive:

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

// exporting type aliases to enforce better type safety (https://github.com/ngrx/example-app)
export type UserInput = User;

@Component({
  selector: 'profile-sidenav',
  styles: [ `
    .profile-image {
      background-repeat: no-repeat;
      background-position: 50%;
      border-radius: 50%;
      width: 100px;
      height: 100px;
    }
  `],
  template: `  
    <div class="profile-image" [ngStyle]="{ 'background-image': url({{image}})">
    <h3>{{ username }}</h3>
  `
})

export class ProfileSidenav {
  @Input() user: UserInput;
  blankImage: string = '../assets/.../camera.png';

  // utilizing "getters" to keep templates clean in 'dumb' components (https://github.com/ngrx/example-app) 
  get username() {
    return this.user.username;
  }
  get image() {
    if (!this.user.image) { return this.cameraImage;
    } else { return this.user.image; }
  }

我认为问题不是可观察到的，因为显示username并执行类似<img *ngIf="image" src="{{ image }}">的操作会渲染图像.我必须访问background-image属性，因为显然这是制作圆形图像的最佳方法，但总的来说，我想知道如何执行此操作.

I don't think the issue is with the observable, since username displays and doing something like <img *ngIf="image" src="{{ image }}"> renders the image. I have to access the background-image attribute because apparently that is the best way to make a circular image, but in general would like to know how to do this.

我最初的[ngStyle]声明有不必要的花括号(ngStyle是可以接受变量的指令)，并且缺少url()和image周围的字符串标签.正确的方法是(如下所述):

My original [ngStyle] declaration had unnecessary curly brackets (ngStyle is a directive that can take a variable), and was missing string tags around url() and image. The correct way is (as answered below) is:

<div class="profile-image" [ngStyle]="{'background-image': 'url(' + image + ')'}"></div>`.

如原始编辑中的所述所述，也可以使用

As stated in the original edit, a solution can also be achieved with the Renderer class in Angular 2. I have yet to do it but think there should be a way with setElementStylesor something like that. I will try to post an example but would love if someone else showed me (and others) how to for the time being.

推荐答案

我认为您应该使用类似的东西:

I think that you should use something like that:

<div class="profile-image"
     [ngStyle]="{ 'background-image': 'url(' + image + ')'}">

其中image是组件的属性.

看到这个问题:

• 如何使用ngStyle添加背景图像( angular2)?

这篇关于Angular 2中背景图像URL的属性属性绑定的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！