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db400f44 | 1 | import { distinct, distinctUntilChanged, filter, map, share, startWith, throttleTime } from 'rxjs/operators' |
bce47964 | 2 | import { Directive, ElementRef, EventEmitter, Input, OnDestroy, OnInit, Output } from '@angular/core' |
db400f44 | 3 | import { fromEvent, Subscription } from 'rxjs' |
0cd4344f C |
4 | |
5 | @Directive({ | |
6 | selector: '[myInfiniteScroller]' | |
7 | }) | |
9af61e84 | 8 | export class InfiniteScrollerDirective implements OnInit, OnDestroy { |
0cd4344f | 9 | @Input() percentLimit = 70 |
aa55a4da | 10 | @Input() autoInit = false |
bce47964 | 11 | @Input() onItself = false |
0cd4344f C |
12 | |
13 | @Output() nearOfBottom = new EventEmitter<void>() | |
0cd4344f C |
14 | |
15 | private decimalLimit = 0 | |
16 | private lastCurrentBottom = -1 | |
9af61e84 | 17 | private scrollDownSub: Subscription |
bce47964 | 18 | private container: HTMLElement |
0cd4344f | 19 | |
bce47964 | 20 | constructor (private el: ElementRef) { |
0cd4344f C |
21 | this.decimalLimit = this.percentLimit / 100 |
22 | } | |
23 | ||
24 | ngOnInit () { | |
aa55a4da | 25 | if (this.autoInit === true) return this.initialize() |
0cd4344f C |
26 | } |
27 | ||
9af61e84 C |
28 | ngOnDestroy () { |
29 | if (this.scrollDownSub) this.scrollDownSub.unsubscribe() | |
9af61e84 C |
30 | } |
31 | ||
0cd4344f | 32 | initialize () { |
bce47964 C |
33 | if (this.onItself) { |
34 | this.container = this.el.nativeElement | |
35 | } | |
36 | ||
6a6d92b1 | 37 | // Emit the last value |
2c6bbd97 | 38 | const throttleOptions = { leading: true, trailing: true } |
6a6d92b1 | 39 | |
bce47964 | 40 | const scrollObservable = fromEvent(this.container || window, 'scroll') |
db400f44 | 41 | .pipe( |
c8861d5d | 42 | startWith(null as string), // FIXME: typings |
db400f44 | 43 | throttleTime(200, undefined, throttleOptions), |
bce47964 | 44 | map(() => this.getScrollInfo()), |
db400f44 C |
45 | distinctUntilChanged((o1, o2) => o1.current === o2.current), |
46 | share() | |
47 | ) | |
0cd4344f C |
48 | |
49 | // Scroll Down | |
9af61e84 | 50 | this.scrollDownSub = scrollObservable |
db400f44 C |
51 | .pipe( |
52 | // Check we scroll down | |
53 | filter(({ current }) => { | |
54 | const res = this.lastCurrentBottom < current | |
0cd4344f | 55 | |
db400f44 C |
56 | this.lastCurrentBottom = current |
57 | return res | |
58 | }), | |
59 | filter(({ current, maximumScroll }) => maximumScroll <= 0 || (current / maximumScroll) > this.decimalLimit) | |
60 | ) | |
0cd4344f | 61 | .subscribe(() => this.nearOfBottom.emit()) |
6a6d92b1 | 62 | } |
bce47964 C |
63 | |
64 | private getScrollInfo () { | |
65 | if (this.container) { | |
66 | return { current: this.container.scrollTop, maximumScroll: this.container.scrollHeight } | |
67 | } | |
68 | ||
69 | return { current: window.scrollY, maximumScroll: document.body.clientHeight - window.innerHeight } | |
70 | } | |
0cd4344f | 71 | } |