我想执行一些基于窗口重新大小事件(在加载和动态)的任务。

目前我的DOM如下:

<div id="Harbour">
    <div id="Port" (window:resize)="onResize($event)" >
        <router-outlet></router-outlet>
    </div>
</div>

事件正确触发

export class AppComponent {
    onResize(event) {
        console.log(event);
    }
}

我如何从这个事件对象检索宽度和高度?

谢谢。


当前回答

我采取的另一种方法是

import {Component, OnInit} from '@angular/core';
import {fromEvent} from "rxjs";
import {debounceTime, map, startWith} from "rxjs/operators";


function windowSizeObserver(dTime = 300) {
  return fromEvent(window, 'resize').pipe(
    debounceTime(dTime),
    map(event => {
      const window = event.target as Window;

      return {width: window.innerWidth, height: window.innerHeight}
    }),
    startWith({width: window.innerWidth, height: window.innerHeight})
  );
}

@Component({
  selector: 'app-root',
  template: `
    <h2>Window Size</h2>
    <div>
      <span>Height: {{(windowSize$ | async)?.height}}</span>
      <span>Width: {{(windowSize$ | async)?.width}}</span>
    </div>
  `
})
export class WindowSizeTestComponent {
  windowSize$ = windowSizeObserver();
}

这里的windowSizeObserver可以在任何组件中重用

其他回答

我所做的就像Johannes Hoppe建议的那样:

import { EventManager } from '@angular/platform-browser'; import { Injectable, EventEmitter } from '@angular/core'; @Injectable() export class ResizeService { public onResize$ = new EventEmitter<{ width: number; height: number; }>(); constructor(eventManager: EventManager) { eventManager.addGlobalEventListener('window', 'resize', event => this.onResize$.emit({ width: event.target.innerWidth, height: event.target.innerHeight })); } getWindowSize(){ this.onResize$.emit({ width: window.innerWidth, height: window.innerHeight }); } }

在app.component.ts:

Import { ResizeService } from ".shared/services/resize.service" import { Component } from "@angular/core" @Component({ selector: "app-root", templateUrl: "./app.component.html", styleUrls: ["./app.component.css"] }) export class AppComponent{ windowSize: {width: number, height: number}; constructor(private resizeService: ResizeService){ } ngOnInit(){ this.resizeService.onResize$.subscribe((value) => { this.windowSize = value; }); this.resizeService.getWindowSize(); } }

然后在你的app.component.html中:

<router-outlet *ngIf = "windowSize? "宽度> 1280 && windowSize?。高度> 700;errorComponent”> < / router-outlet > < ng-template # errorComponent > < app-error-component > < / app-error-component > < / ng-template >

我写这个库是为了找到Angular中组件边界大小改变(重新调整大小)的方法,希望能帮助到其他人。你可以把它放在根组件上,会做和窗口大小调整一样的事情。

步骤1:导入模块

import { BoundSensorModule } from 'angular-bound-sensor';

@NgModule({
  (...)
  imports: [
    BoundSensorModule,
  ],
})
export class AppModule { }

步骤2:添加如下指令

<简单的组件boundSensor > < /简单的组件>

步骤3:接收边界大小的详细信息

import { HostListener } from '@angular/core';

@Component({
  selector: 'simple-component'
  (...)
})
class SimpleComponent {
  @HostListener('resize', ['$event'])
  onResize(event) {
    console.log(event.detail);
  }
}
<div (window:resize)="onResize($event)"
onResize(event) {
  event.target.innerWidth;
}

或者使用HostListener装饰器:

@HostListener('window:resize', ['$event'])
onResize(event) {
  event.target.innerWidth;
}

支持的全局目标有window、document和body。

在https://github.com/angular/angular/issues/13248在Angular中实现之前,强制订阅DOM事件并使用RXJS来减少事件的数量(如其他一些答案所示)会更好地提高性能。

我采取的另一种方法是

import {Component, OnInit} from '@angular/core';
import {fromEvent} from "rxjs";
import {debounceTime, map, startWith} from "rxjs/operators";


function windowSizeObserver(dTime = 300) {
  return fromEvent(window, 'resize').pipe(
    debounceTime(dTime),
    map(event => {
      const window = event.target as Window;

      return {width: window.innerWidth, height: window.innerHeight}
    }),
    startWith({width: window.innerWidth, height: window.innerHeight})
  );
}

@Component({
  selector: 'app-root',
  template: `
    <h2>Window Size</h2>
    <div>
      <span>Height: {{(windowSize$ | async)?.height}}</span>
      <span>Width: {{(windowSize$ | async)?.width}}</span>
    </div>
  `
})
export class WindowSizeTestComponent {
  windowSize$ = windowSizeObserver();
}

这里的windowSizeObserver可以在任何组件中重用

在angular CDK中有一个ViewportRuler服务。它在区域外运行,支持方向改变和大小调整。它也适用于服务器端渲染。

@Component({
  selector: 'my-app',
  template: `
    <p>Viewport size: {{ width }} x {{ height }}</p>
  `
})
export class AppComponent implements OnDestroy {
  width: number;
  height: number;
  private readonly viewportChange = this.viewportRuler
    .change(200)
    .subscribe(() => this.ngZone.run(() => this.setSize()));
  constructor(
    private readonly viewportRuler: ViewportRuler,
    private readonly ngZone: NgZone
  ) {
    // Change happens well, on change. The first load is not a change, so we init the values here. (You can use `startWith` operator too.)
    this.setSize();
  }
  // Never forget to unsubscribe!
  ngOnDestroy() {
    this.viewportChange.unsubscribe();
  }

  private setSize() {
    const { width, height } = this.viewportRuler.getViewportSize();
    this.width = width;
    this.height = height;
  }
}

ViewportRuler的Stackblitz示例

好处是,它限制了更改检测周期(它只会在区域中运行回调时触发),而(window:resize)将在每次调用时触发更改检测。