]>
Commit | Line | Data |
---|---|---|
db400f44 | 1 | import { distinct, distinctUntilChanged, filter, map, share, startWith, throttleTime } from 'rxjs/operators' |
9af61e84 | 2 | import { Directive, 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 C |
9 | @Input() containerHeight: number |
10 | @Input() pageHeight: number | |
a8ecc6f6 | 11 | @Input() firstLoadedPage = 1 |
0cd4344f | 12 | @Input() percentLimit = 70 |
aa55a4da | 13 | @Input() autoInit = false |
e2f01c47 | 14 | @Input() container = document.body |
0cd4344f C |
15 | |
16 | @Output() nearOfBottom = new EventEmitter<void>() | |
17 | @Output() nearOfTop = new EventEmitter<void>() | |
18 | @Output() pageChanged = new EventEmitter<number>() | |
19 | ||
20 | private decimalLimit = 0 | |
21 | private lastCurrentBottom = -1 | |
22 | private lastCurrentTop = 0 | |
9af61e84 C |
23 | private scrollDownSub: Subscription |
24 | private scrollUpSub: Subscription | |
25 | private pageChangeSub: Subscription | |
a8ecc6f6 | 26 | private middleScreen: number |
0cd4344f C |
27 | |
28 | constructor () { | |
29 | this.decimalLimit = this.percentLimit / 100 | |
30 | } | |
31 | ||
32 | ngOnInit () { | |
aa55a4da | 33 | if (this.autoInit === true) return this.initialize() |
0cd4344f C |
34 | } |
35 | ||
9af61e84 C |
36 | ngOnDestroy () { |
37 | if (this.scrollDownSub) this.scrollDownSub.unsubscribe() | |
38 | if (this.scrollUpSub) this.scrollUpSub.unsubscribe() | |
39 | if (this.pageChangeSub) this.pageChangeSub.unsubscribe() | |
40 | } | |
41 | ||
0cd4344f | 42 | initialize () { |
a8ecc6f6 C |
43 | this.middleScreen = window.innerHeight / 2 |
44 | ||
6a6d92b1 | 45 | // Emit the last value |
2c6bbd97 | 46 | const throttleOptions = { leading: true, trailing: true } |
6a6d92b1 | 47 | |
0cd4344f | 48 | const scrollObservable = fromEvent(window, 'scroll') |
db400f44 C |
49 | .pipe( |
50 | startWith(null), | |
51 | throttleTime(200, undefined, throttleOptions), | |
e2f01c47 | 52 | map(() => ({ current: window.scrollY, maximumScroll: this.container.clientHeight - window.innerHeight })), |
db400f44 C |
53 | distinctUntilChanged((o1, o2) => o1.current === o2.current), |
54 | share() | |
55 | ) | |
0cd4344f C |
56 | |
57 | // Scroll Down | |
9af61e84 | 58 | this.scrollDownSub = scrollObservable |
db400f44 C |
59 | .pipe( |
60 | // Check we scroll down | |
61 | filter(({ current }) => { | |
62 | const res = this.lastCurrentBottom < current | |
0cd4344f | 63 | |
db400f44 C |
64 | this.lastCurrentBottom = current |
65 | return res | |
66 | }), | |
67 | filter(({ current, maximumScroll }) => maximumScroll <= 0 || (current / maximumScroll) > this.decimalLimit) | |
68 | ) | |
0cd4344f C |
69 | .subscribe(() => this.nearOfBottom.emit()) |
70 | ||
71 | // Scroll up | |
9af61e84 | 72 | this.scrollUpSub = scrollObservable |
db400f44 C |
73 | .pipe( |
74 | // Check we scroll up | |
75 | filter(({ current }) => { | |
76 | const res = this.lastCurrentTop > current | |
0cd4344f | 77 | |
db400f44 C |
78 | this.lastCurrentTop = current |
79 | return res | |
80 | }), | |
81 | filter(({ current, maximumScroll }) => { | |
82 | return current !== 0 && (1 - (current / maximumScroll)) > this.decimalLimit | |
83 | }) | |
84 | ) | |
0cd4344f C |
85 | .subscribe(() => this.nearOfTop.emit()) |
86 | ||
87 | // Page change | |
9af61e84 | 88 | this.pageChangeSub = scrollObservable |
db400f44 C |
89 | .pipe( |
90 | distinct(), | |
91 | map(({ current }) => this.calculateCurrentPage(current)), | |
92 | distinctUntilChanged() | |
93 | ) | |
0cd4344f C |
94 | .subscribe(res => this.pageChanged.emit(res)) |
95 | } | |
96 | ||
6a6d92b1 | 97 | private calculateCurrentPage (current: number) { |
a8ecc6f6 C |
98 | const scrollY = current + this.middleScreen |
99 | ||
100 | const page = Math.max(1, Math.ceil(scrollY / this.pageHeight)) | |
101 | ||
102 | // Offset page | |
103 | return page + (this.firstLoadedPage - 1) | |
6a6d92b1 | 104 | } |
0cd4344f | 105 | } |