我使用 @HostBinding
与 Chrome 的拖放 API 一起设置一个类,如下所示:
@Directive({ selector: '[sortable-article]' })
export class SortableArticleComponent {
@HostBinding('class.dragged-element')
isDraggedArticle: boolean = false;
constructor(elRef: ElementRef, private ref: ChangeDetectorRef, private appRef: ApplicationRef, private dndService: ArticleDndService) {
this.el = elRef.nativeElement;
Observable.fromEvent(this.el, 'dragstart').subscribe(e => this.onDragStart(<DragEvent> e));
Observable.fromEvent(this.el, 'drop').subscribe(e => this.onDrop(<DragEvent> e));
}
onDragStart(event: DragEvent) {
this.isDraggedArticle = true;
}
onDrop(event: DragEvent) {
event.preventDefault();
this.isDraggedArticle = false;
}
}
发生的情况是,isDraggedArticle
类没有从元素中删除,但我不知道为什么。我尝试添加
this.ref.detectChanges();
this.appRef.tick();
onDrop 方法(其中 ref
是一个 ChangeDetectorRef
而 appRef
是一个 ApplicationRef
),但是它没有帮助。
最佳答案
我想我找到了问题的解决方案: drop
事件不会在已拖动的项目上触发,但会在拖放到其上的项目上触发。这意味着我需要在 dragend
回调中设置 this.isDraggedArticle = false
而不是设置:
@Directive({ selector: '[sortable-article]' })
export class SortableArticleComponent {
@HostBinding('class.dragged-element')
isDraggedArticle: boolean = false;
constructor(elRef: ElementRef, private ref: ChangeDetectorRef, private appRef: ApplicationRef, private dndService: ArticleDndService) {
this.el = elRef.nativeElement;
Observable.fromEvent(this.el, 'dragstart').subscribe(e => this.onDragStart(<DragEvent> e));
Observable.fromEvent(this.el, 'dragend').subscribe(e => this.onDragEnd(<DragEvent> e));
}
onDragStart(event: DragEvent) {
this.isDraggedArticle = true;
}
onDragEnd(event: DragEvent) {
this.isDraggedArticle = false;
}
}
关于javascript - Angular 2 不检测@HostBinding 的变化,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/43546938/