typescript NG2-进步，bar.ts

Posted 2021-05-21

import {Component, ViewEncapsulation, ElementRef, Inject, EventEmitter, Output, ViewChild} from 'angular2/core';
import {Input} from 'angular2/core';
import {ChangeDetectionStrategy} from 'angular2/core';
import {DatePipe} from 'angular2/common';
import {PlayerDurationPipe} from './playerDurationPipe';
import {Observable} from 'rxjs/Observable';
import {Subject}  from 'rxjs/Subject';
import {Action} from '@ngrx/store';
import {FilmStrip} from './filmStrip/filmStrip';
export interface ScrubberHoverEvent {
  pixels: number;
  seconds: number;
}

@Component({
  changeDetection: ChangeDetectionStrategy.OnPush,
  selector: 'progress-bar',
  directives: [FilmStrip],
  pipes: [DatePipe, PlayerDurationPipe],
  host: {
    '(mouseenter)': 'showScrubberHandle()',
    '(mouseleave)': 'hideScrubberHandle()',
    '(mousemove)': 'scrubberHoverEvent.next($event)'
  },
  template: `
    <film-strip *ngIf="!state.isLive && state.filmStripUrl" [filmStripUrl]="state.filmStripUrl" [class.visible]="scrubberHandleVisibility" [position]="scrubberHoverEvent" [style.left]="scrubberHandlePosition | async" ></film-strip>
    <div #scrubber class="scrubber" (click)="changePosition.next($event)">
      <div class="scrubber-handle" [class.visible]="scrubberHandleVisibility" [style.left]="scrubberHandlePosition | async"></div>
      <div class="progress-container" [style.width]="progress"></div>
      <div class="buffer-container" [style.width]="buffer"></div>
    </div>
    <span class="remaining">{{remaining | playerDuration}}</span>
  `,
  styles: [
    require('./progressBar.scss')
  ]
})
/**
 * @description Manages the playback location and filmstrip.
 * @class ProgressBar
 */
export class ProgressBar {
  /**
   * @description The amount loaded in percent
   * @type {string} eg. '100%'
   */
  buffer: string;
  /**
   * @description The amount watched or position in the media.
   * @type {string} eg. '10%'
   */
  progress: string;
  /**
   * @description The amount left to watch in miliseconds
   * @type {number} eg. 10000
   */
  remaining: number;

  /**
   * @description The Hover over the progress bar event stream, maps the raw dom event to a ScrubberHoverEvent.
   * @type {Observable<ScrubberHoverEvent>}
   */
  scrubberHoverEvent: Observable<any>;

  /**
   * @description Observes the hover event and maps it to a pixel value where the scrubber handle should be positioned.
   * @type {Observable<string>}
   */
  scrubberHandlePosition: Observable<string>;

  /**
   * @description Listens to the click on the scrubber bar and tells the component to emit the latest value from the
   *   scrubber hover
   * @type {Observable<ScrubberHoverEvent>}
   */
  changePosition: Observable<any>;

  /**
   * @description Internal state of the scrubber handle. TODO - LOW -> map this into an observable
   * @type {boolean}
   */
  scrubberHandleVisibility: boolean = false;

  /**
   * @description The player state input (important :)
   * @type {PlayerState}
   */
  @Input()
  state;

  /**
   * @description Events coming out of this component
   * @type {EventEmitter}
   */
  @Output()
  progressBarEvent: EventEmitter<Action> = new EventEmitter();

  /**
   * @description The scrubber bar element
   * @type {ElementRef}
   */
  @ViewChild('scrubber')
  scrubber: ElementRef;

  ngOnInit() {
    //Listen to MouseMove
    this.scrubberHoverEvent = new Subject().map((event: MouseEvent): ScrubberHoverEvent => {
      //The bounded position
      let pos = Math.min(Math.max(0, event.offsetX), this.scrubber.nativeElement.offsetWidth);
      //The ScrubberHoverEvent
      return {
        seconds: (pos / this.scrubber.nativeElement.offsetWidth) * this.state.duration, //Millisecond position
        pixels: pos //Pixel position on page
      };
    });

    this.scrubberHandlePosition = this.scrubberHoverEvent
      .map(
        (data: ScrubberHoverEvent) => {
          return `${data.pixels}px`;
        }
      );

    //Listen to the click and grab the last value from scrubberHover.
    this.changePosition = new Subject().withLatestFrom(this.scrubberHoverEvent, (click: MouseEvent, hover: ScrubberHoverEvent): ScrubberHoverEvent => {
      return hover;
    });

    this.changePosition.subscribe((data: ScrubberHoverEvent): void => {
      this.progressBarEvent.emit({type: 'seek', payload: data.seconds});
    });
  }

  ngOnChanges() {
    //When the input changes recalc the percentages.
    this.buffer = `${this.state.percentLoaded}%`;
    this.progress = `${this.state.percentWatched}%`;
    this.remaining = this.state.duration - this.state.position;
  }

  showScrubberHandle() {
    this.scrubberHandleVisibility = true;
  }

  hideScrubberHandle() {
    this.scrubberHandleVisibility = false;
  }
}