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/**
* @license
* Copyright Google Inc. All Rights Reserved.
*
* Use of this source code is governed by an MIT-style license that can be
* found in the LICENSE file at https://angular.io/license
*/
/* tslint:disable:array-type member-access variable-name typedef
only-arrow-functions directive-class-suffix component-class-suffix
component-selector*/
import {Subscription} from 'rxjs/Subscription';
import {OverlayRef} from '../overlay-ref';
import {ScrollDispatcher} from './scroll-dispatcher';
import {getMdScrollStrategyAlreadyAttachedError, ScrollStrategy} from './scroll-strategy';
/**
* Config options for the RepositionScrollStrategy.
*/
export interface RepositionScrollStrategyConfig { scrollThrottle?: number; }
/**
* Strategy that will update the element position as the user is scrolling.
*/
export class RepositionScrollStrategy implements ScrollStrategy {
private _scrollSubscription: Subscription|null = null;
private _overlayRef: OverlayRef;
constructor(
private _scrollDispatcher: ScrollDispatcher,
private _config?: RepositionScrollStrategyConfig) {}
attach(overlayRef: OverlayRef) {
if (this._overlayRef) {
throw getMdScrollStrategyAlreadyAttachedError();
}
this._overlayRef = overlayRef;
}
enable() {
if (!this._scrollSubscription) {
const throttle = this._config ? this._config.scrollThrottle : 0;
this._scrollSubscription =
this._scrollDispatcher.scrolled(throttle, () => {
this._overlayRef.updatePosition();
});
}
}
disable() {
if (this._scrollSubscription) {
this._scrollSubscription.unsubscribe();
this._scrollSubscription = null;
}
}
}
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