gerrit.onap Code Review - sdc/sdc-workflow-designer.git/blob

   1 /**
   2  * @license
   3  * Copyright Google Inc. All Rights Reserved.
   4  *
   5  * Use of this source code is governed by an MIT-style license that can be
   6  * found in the LICENSE file at https://angular.io/license
   7  */
   8 /* tslint:disable:array-type member-access variable-name typedef
   9  only-arrow-functions directive-class-suffix component-class-suffix
  10  component-selector*/
  11 import {Subscription} from 'rxjs/Subscription';
  12
  13 import {OverlayRef} from '../overlay-ref';
  14
  15 import {ScrollDispatcher} from './scroll-dispatcher';
  16 import {getMdScrollStrategyAlreadyAttachedError, ScrollStrategy} from './scroll-strategy';
  17
  18 /**
  19  * Config options for the RepositionScrollStrategy.
  20  */
  21 export interface RepositionScrollStrategyConfig { scrollThrottle?: number; }
  22
  23 /**
  24  * Strategy that will update the element position as the user is scrolling.
  25  */
  26 export class RepositionScrollStrategy implements ScrollStrategy {
  27   private _scrollSubscription: Subscription|null = null;
  28   private _overlayRef: OverlayRef;
  29
  30   constructor(
  31                 private _scrollDispatcher: ScrollDispatcher,
  32                 private _config?: RepositionScrollStrategyConfig) {}
  33
  34   attach(overlayRef: OverlayRef) {
  35         if (this._overlayRef) {
  36                 throw getMdScrollStrategyAlreadyAttachedError();
  37         }
  38
  39         this._overlayRef = overlayRef;
  40   }
  41
  42   enable() {
  43         if (!this._scrollSubscription) {
  44                 const throttle = this._config ? this._config.scrollThrottle : 0;
  45
  46                 this._scrollSubscription =
  47                         this._scrollDispatcher.scrolled(throttle, () => {
  48                         this._overlayRef.updatePosition();
  49                         });
  50         }
  51   }
  52
  53   disable() {
  54         if (this._scrollSubscription) {
  55                 this._scrollSubscription.unsubscribe();
  56                 this._scrollSubscription = null;
  57         }
  58   }
  59 }