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($event)" >
<router-outlet></router-outlet>
</div>
</div>
事件正确触发
export class AppComponent {
onResize(event) {
console.log(event);
}
}
我如何从这个事件对象检索宽度和高度?
谢谢。
我采取的另一种方法是
import {Component, OnInit} from '@angular/core';
import {fromEvent} from "rxjs";
import {debounceTime, map, startWith} from "rxjs/operators";
function windowSizeObserver(dTime = 300) {
return fromEvent(window, 'resize').pipe(
debounceTime(dTime),
map(event => {
const window = event.target as Window;
return {width: window.innerWidth, height: window.innerHeight}
}),
startWith({width: window.innerWidth, height: window.innerHeight})
);
}
@Component({
selector: 'app-root',
template: `
<h2>Window Size</h2>
<div>
<span>Height: {{(windowSize$ | 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
基于@cgatian的解决方案,我建议简化如下:
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',
e => this.onResize$.emit({
width: e.target.innerWidth,
height: e.target.innerHeight
}));
}
}
用法:
import { Component } from '@angular/core';
import { ResizeService } from './resize-service';
@Component({
selector: 'my-component',
template: `{{ rs.onResize$ | async | json }}`
})
export class MyComponent {
constructor(private rs: ResizeService) { }
}
<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。
如果你想在调整大小完成后只发生一个事件,最好使用RxJS和debounceTime:
debounceTime:丢弃输出间隔时间少于指定时间的发出值。
在运行代码之前,他在两个事件之间等待> 0.5s。
简单地说,它在执行下一个代码之前等待大小调整完成。
// RxJS v6+
import { fromEvent } from 'rxjs';
import { debounceTime, map } from 'rxjs/operators';
...
const resize$ = fromEvent(window, 'resize');
resize$
.pipe(
map((i: any) => i),
debounceTime(500) // He waits > 0.5s between 2 events emitted before running the next.
)
.subscribe((event) => {
console.log('resize is finished');
});
堆栈闪电战
这并不是问题的确切答案,但它可以帮助那些需要检测任何元素的大小变化的人。
我已经创建了一个库,可以将调整大小的事件添加到任何元素中——Angular Resize event。
它内部使用resizsensor从CSS元素查询。
示例使用
HTML
<div (resized)="onResized($event)"></div>
打印稿
@Component({...})
class MyComponent {
width: number;
height: number;
onResized(event: ResizedEvent): void {
this.width = event.newWidth;
this.height = event.newHeight;
}
}
我所做的就像Johannes Hoppe建议的那样:
import { EventManager } from '@angular/platform-browser';
import { Injectable, EventEmitter } from '@angular/core';
@Injectable()
export class ResizeService {
public onResize$ = 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 >