Cancel drag on key press Angular cdk Drag and Drop

问题

I´m working in a application implementing the new drag and drop from angular material CDK and i´m trying to cancel the drag event of the element pressing Esc, i mean, i start dragging the element but if i press Esc while i´m dragging the element, it should go back to the position from where i start dragging it, so far i haven´t found a way to do this, does anyone know how can i do this. There nothing in the cdk documentation about this any idea. i try doing something like this.

Template

<div cdkDropList class="example-list" (cdkDropListDropped)="drop($event)">
  <div class="example-box" *ngFor="let movie of movies" (cdkDragEnded)="onDragEnded($event)" cdkDrag>{{movie}}</div>
</div>

Ts component

onDragEnded(event: CdkDragEnd) {
  console.log(event)
  event.source.element.nativeElement.style.transform = 'none';
  const source: any = event.source;
  source._passiveTransform = { x: 0, y: 0 };
}

but no success so far.

回答1:

I also faced this problem for a long time. Finally I could fix it by dispatching a mouseup event that will act as the user releasing the mouse.

@HostListener('window:keyup', ['$event'])
handleKeyboardEvent(event: KeyboardEvent) {
    if (event.key === 'Escape') {
        document.dispatchEvent(new Event('mouseup'));
    }
}

This is an extremely hacky solution and comes with it's down sides. In fact, you are not cancelling the drag but instead dropping. Meaning that if you are hovering a cdkDropList or one is active it will trigger the cdkDropListDropped emmiter for that list. Something you can easily workaround by adding a flag.

private _canceledByEsq = false;

@HostListener('window:keyup', ['$event'])
handleKeyboardEvent(event: KeyboardEvent) {
    if (event.key === 'Escape') {
        this._canceledByEsq = true;
        document.dispatchEvent(new Event('mouseup'));
    }
}

handleDrop() {
    if (!this._canceledByEsq) {
        // Do my data manipulations
    }
}

Hope this helps you... :)

回答2:

You can move the dragged item to a position using:

event['source']['element']['nativeElement']['style']['transform'] = 'translate3d(0,0,0)';
event['source']['_dragRef']['_activeTransform'] = {x: 0, y: 0};
event['source']['_dragRef']['_passiveTransform'] = {x: 0, y: 0};

回答3:

The best way to do it is to call event.source._dragRef.reset(); (as @AleRubis mentioned in comment) on ESC key press. Now the question is from where you can get that _dragRef outside cdkDrag events (ESC key event), you can save it in a component variable like this when drag starts.

Component:

cdkDragStarted = (event) => { this.dragRef = event.source._dragRef; }

Template:

<p cdkDrag (cdkDragStarted)="cdkDragStarted($event)"> Draggable paragraph </p>

回答4:

You can use something like...

@HostListener('window:keyup', ['$event'])
handleKeyboardEvent(event: KeyboardEvent) {
    if (event.code === 'Escape') {
        // call dragend event
    }
}

来源：https://stackoverflow.com/questions/53609182/cancel-drag-on-key-press-angular-cdk-drag-and-drop

标签

javascript

angular

angular-material

angular-cdk