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($event)" >
<router-outlet></router-outlet>
</div>
</div>
事件正确触发
export class AppComponent {
onResize(event) {
console.log(event);
}
}
我如何从这个事件对象检索宽度和高度?
谢谢。
@Günter的答案是正确的。我只是想提出另一种方法。
你也可以在@Component()装饰器中添加主机绑定。你可以像这样把事件和所需的函数调用放在host-metadata-property中:
@Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.css'],
host: {
'(window:resize)': 'onResize($event)'
}
})
export class AppComponent{
onResize(event){
event.target.innerWidth; // window width
}
}
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。
我检查了大部分答案。然后决定查看关于布局的Angular文档。
Angular有自己的观察者来检测不同的大小,而且很容易实现到组件或服务中。
一个简单的例子是:
import {BreakpointObserver, Breakpoints} from '@angular/cdk/layout';
@ component({…})
类MyComponent {
构造函数(breakpointObserver: breakpointObserver) {
breakpointObserver.observe ([
断点。HandsetLandscape,
断点。HandsetPortrait
])。订阅(result => {
If (result.matches) {
this.activateHandsetLayout ();
}
});
}
}
希望能有所帮助
我知道很久以前就有人问过这个问题,但现在有更好的方法来做到这一点!我不确定是否有人会看到这个答案。显然你的进口:
import { fromEvent, Observable, Subscription } from "rxjs";
然后在你的组件中:
resizeObservable$: Observable<Event>
resizeSubscription$: Subscription
ngOnInit() {
this.resizeObservable$ = fromEvent(window, 'resize')
this.resizeSubscription$ = this.resizeObservable$.subscribe( evt => {
console.log('event: ', evt)
})
}
那么一定要取消订阅destroy!
ngOnDestroy() {
this.resizeSubscription$.unsubscribe()
}
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