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Commit | Line | Data |
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d142c7b9 | 1 | import { fromEvent, Observable, Subscription } from 'rxjs' |
14aa8556 | 2 | import { distinctUntilChanged, filter, map, share, startWith, throttleTime } from 'rxjs/operators' |
617f4f5c | 3 | import { AfterViewChecked, Directive, ElementRef, EventEmitter, Input, OnDestroy, OnInit, Output } from '@angular/core' |
0cd4344f C |
4 | |
5 | @Directive({ | |
6 | selector: '[myInfiniteScroller]' | |
7 | }) | |
617f4f5c | 8 | export class InfiniteScrollerDirective implements OnInit, OnDestroy, AfterViewChecked { |
0cd4344f | 9 | @Input() percentLimit = 70 |
aa55a4da | 10 | @Input() autoInit = false |
bce47964 | 11 | @Input() onItself = false |
ad453580 | 12 | @Input() dataObservable: Observable<any[]> |
0cd4344f C |
13 | |
14 | @Output() nearOfBottom = new EventEmitter<void>() | |
0cd4344f C |
15 | |
16 | private decimalLimit = 0 | |
17 | private lastCurrentBottom = -1 | |
9af61e84 | 18 | private scrollDownSub: Subscription |
bce47964 | 19 | private container: HTMLElement |
0cd4344f | 20 | |
ad453580 C |
21 | private checkScroll = false |
22 | ||
bce47964 | 23 | constructor (private el: ElementRef) { |
0cd4344f C |
24 | this.decimalLimit = this.percentLimit / 100 |
25 | } | |
26 | ||
617f4f5c | 27 | ngAfterViewChecked () { |
ad453580 C |
28 | if (this.checkScroll) { |
29 | this.checkScroll = false | |
30 | ||
617f4f5c C |
31 | // Wait HTML update |
32 | setTimeout(() => { | |
33 | if (this.hasScroll() === false) this.nearOfBottom.emit() | |
34 | }) | |
ad453580 C |
35 | } |
36 | } | |
37 | ||
0cd4344f | 38 | ngOnInit () { |
aa55a4da | 39 | if (this.autoInit === true) return this.initialize() |
0cd4344f C |
40 | } |
41 | ||
9af61e84 C |
42 | ngOnDestroy () { |
43 | if (this.scrollDownSub) this.scrollDownSub.unsubscribe() | |
9af61e84 C |
44 | } |
45 | ||
0cd4344f | 46 | initialize () { |
ad453580 C |
47 | this.container = this.onItself |
48 | ? this.el.nativeElement | |
49 | : document.documentElement | |
bce47964 | 50 | |
6a6d92b1 | 51 | // Emit the last value |
2c6bbd97 | 52 | const throttleOptions = { leading: true, trailing: true } |
6a6d92b1 | 53 | |
ad453580 C |
54 | const scrollableElement = this.onItself ? this.container : window |
55 | const scrollObservable = fromEvent(scrollableElement, 'scroll') | |
db400f44 | 56 | .pipe( |
14aa8556 | 57 | startWith(true), |
db400f44 | 58 | throttleTime(200, undefined, throttleOptions), |
bce47964 | 59 | map(() => this.getScrollInfo()), |
db400f44 C |
60 | distinctUntilChanged((o1, o2) => o1.current === o2.current), |
61 | share() | |
62 | ) | |
0cd4344f C |
63 | |
64 | // Scroll Down | |
9af61e84 | 65 | this.scrollDownSub = scrollObservable |
db400f44 | 66 | .pipe( |
ad453580 C |
67 | filter(({ current }) => this.isScrollingDown(current)), |
68 | filter(({ current, maximumScroll }) => (current / maximumScroll) > this.decimalLimit) | |
db400f44 | 69 | ) |
0cd4344f | 70 | .subscribe(() => this.nearOfBottom.emit()) |
ad453580 C |
71 | |
72 | if (this.dataObservable) { | |
73 | this.dataObservable | |
74 | .pipe(filter(d => d.length !== 0)) | |
75 | .subscribe(() => this.checkScroll = true) | |
76 | } | |
6a6d92b1 | 77 | } |
bce47964 C |
78 | |
79 | private getScrollInfo () { | |
ad453580 C |
80 | return { current: this.container.scrollTop, maximumScroll: this.getMaximumScroll() } |
81 | } | |
82 | ||
83 | private getMaximumScroll () { | |
d142c7b9 C |
84 | const elementHeight = this.onItself ? this.container.clientHeight : window.innerHeight |
85 | ||
86 | return this.container.scrollHeight - elementHeight | |
ad453580 C |
87 | } |
88 | ||
89 | private hasScroll () { | |
90 | return this.getMaximumScroll() > 0 | |
91 | } | |
92 | ||
93 | private isScrollingDown (current: number) { | |
94 | const result = this.lastCurrentBottom < current | |
bce47964 | 95 | |
ad453580 C |
96 | this.lastCurrentBottom = current |
97 | return result | |
bce47964 | 98 | } |
0cd4344f | 99 | } |