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0cd4344f | 1 | import { Directive, EventEmitter, Input, OnInit, Output } from '@angular/core' |
8cac1b64 | 2 | import 'rxjs/add/operator/debounceTime' |
0cd4344f | 3 | import 'rxjs/add/operator/distinct' |
3bcfff7f | 4 | import 'rxjs/add/operator/distinctUntilChanged' |
8cac1b64 C |
5 | import 'rxjs/add/operator/filter' |
6 | import 'rxjs/add/operator/map' | |
0cd4344f C |
7 | import 'rxjs/add/operator/startWith' |
8 | import { fromEvent } from 'rxjs/observable/fromEvent' | |
9 | ||
10 | @Directive({ | |
11 | selector: '[myInfiniteScroller]' | |
12 | }) | |
13 | export class InfiniteScrollerDirective implements OnInit { | |
14 | private static PAGE_VIEW_TOP_MARGIN = 500 | |
15 | ||
16 | @Input() containerHeight: number | |
17 | @Input() pageHeight: number | |
18 | @Input() percentLimit = 70 | |
19 | @Input() autoLoading = false | |
20 | ||
21 | @Output() nearOfBottom = new EventEmitter<void>() | |
22 | @Output() nearOfTop = new EventEmitter<void>() | |
23 | @Output() pageChanged = new EventEmitter<number>() | |
24 | ||
25 | private decimalLimit = 0 | |
26 | private lastCurrentBottom = -1 | |
27 | private lastCurrentTop = 0 | |
28 | ||
29 | constructor () { | |
30 | this.decimalLimit = this.percentLimit / 100 | |
31 | } | |
32 | ||
33 | ngOnInit () { | |
34 | if (this.autoLoading === true) return this.initialize() | |
35 | } | |
36 | ||
37 | initialize () { | |
38 | const scrollObservable = fromEvent(window, 'scroll') | |
39 | .startWith(true) | |
40 | .map(() => ({ current: window.scrollY, maximumScroll: document.body.clientHeight - window.innerHeight })) | |
41 | ||
42 | // Scroll Down | |
43 | scrollObservable | |
44 | // Check we scroll down | |
45 | .filter(({ current }) => { | |
46 | const res = this.lastCurrentBottom < current | |
47 | ||
48 | this.lastCurrentBottom = current | |
49 | return res | |
50 | }) | |
51 | .filter(({ current, maximumScroll }) => maximumScroll <= 0 || (current / maximumScroll) > this.decimalLimit) | |
52 | .debounceTime(200) | |
53 | .distinct() | |
54 | .subscribe(() => this.nearOfBottom.emit()) | |
55 | ||
56 | // Scroll up | |
57 | scrollObservable | |
58 | // Check we scroll up | |
59 | .filter(({ current }) => { | |
60 | const res = this.lastCurrentTop > current | |
61 | ||
62 | this.lastCurrentTop = current | |
63 | return res | |
64 | }) | |
65 | .filter(({ current, maximumScroll }) => { | |
66 | return current !== 0 && (1 - (current / maximumScroll)) > this.decimalLimit | |
67 | }) | |
68 | .debounceTime(200) | |
69 | .distinct() | |
70 | .subscribe(() => this.nearOfTop.emit()) | |
71 | ||
72 | // Page change | |
73 | scrollObservable | |
74 | .debounceTime(500) | |
75 | .distinct() | |
76 | .map(({ current }) => Math.max(1, Math.round((current + InfiniteScrollerDirective.PAGE_VIEW_TOP_MARGIN) / this.pageHeight))) | |
77 | .distinctUntilChanged() | |
78 | .subscribe(res => this.pageChanged.emit(res)) | |
79 | } | |
80 | ||
81 | } |