]>
Commit | Line | Data |
---|---|---|
1 | import { Directive, EventEmitter, Input, OnInit, Output } from '@angular/core' | |
2 | import 'rxjs/add/operator/debounceTime' | |
3 | import 'rxjs/add/operator/distinct' | |
4 | import 'rxjs/add/operator/distinctUntilChanged' | |
5 | import 'rxjs/add/operator/filter' | |
6 | import 'rxjs/add/operator/map' | |
7 | import 'rxjs/add/operator/startWith' | |
8 | import 'rxjs/add/operator/throttleTime' | |
9 | import { fromEvent } from 'rxjs/observable/fromEvent' | |
10 | import 'rxjs/add/operator/share' | |
11 | ||
12 | @Directive({ | |
13 | selector: '[myInfiniteScroller]' | |
14 | }) | |
15 | export class InfiniteScrollerDirective implements OnInit { | |
16 | private static PAGE_VIEW_TOP_MARGIN = 500 | |
17 | ||
18 | @Input() containerHeight: number | |
19 | @Input() pageHeight: number | |
20 | @Input() percentLimit = 70 | |
21 | @Input() autoLoading = false | |
22 | ||
23 | @Output() nearOfBottom = new EventEmitter<void>() | |
24 | @Output() nearOfTop = new EventEmitter<void>() | |
25 | @Output() pageChanged = new EventEmitter<number>() | |
26 | ||
27 | private decimalLimit = 0 | |
28 | private lastCurrentBottom = -1 | |
29 | private lastCurrentTop = 0 | |
30 | ||
31 | constructor () { | |
32 | this.decimalLimit = this.percentLimit / 100 | |
33 | } | |
34 | ||
35 | ngOnInit () { | |
36 | if (this.autoLoading === true) return this.initialize() | |
37 | } | |
38 | ||
39 | initialize () { | |
40 | // Emit the last value | |
41 | const throttleOptions = { leading: false, trailing: true } | |
42 | ||
43 | const scrollObservable = fromEvent(window, 'scroll') | |
44 | .startWith(true) | |
45 | .throttleTime(200, undefined, throttleOptions) | |
46 | .map(() => ({ current: window.scrollY, maximumScroll: document.body.clientHeight - window.innerHeight })) | |
47 | .share() | |
48 | ||
49 | // Scroll Down | |
50 | scrollObservable | |
51 | // Check we scroll down | |
52 | .filter(({ current }) => { | |
53 | const res = this.lastCurrentBottom < current | |
54 | ||
55 | this.lastCurrentBottom = current | |
56 | return res | |
57 | }) | |
58 | .filter(({ current, maximumScroll }) => maximumScroll <= 0 || (current / maximumScroll) > this.decimalLimit) | |
59 | .subscribe(() => this.nearOfBottom.emit()) | |
60 | ||
61 | // Scroll up | |
62 | scrollObservable | |
63 | // Check we scroll up | |
64 | .filter(({ current }) => { | |
65 | const res = this.lastCurrentTop > current | |
66 | ||
67 | this.lastCurrentTop = current | |
68 | return res | |
69 | }) | |
70 | .filter(({ current, maximumScroll }) => { | |
71 | return current !== 0 && (1 - (current / maximumScroll)) > this.decimalLimit | |
72 | }) | |
73 | .subscribe(() => this.nearOfTop.emit()) | |
74 | ||
75 | // Page change | |
76 | scrollObservable | |
77 | .distinct() | |
78 | .map(({ current }) => this.calculateCurrentPage(current)) | |
79 | .distinctUntilChanged() | |
80 | .subscribe(res => this.pageChanged.emit(res)) | |
81 | } | |
82 | ||
83 | private calculateCurrentPage (current: number) { | |
84 | return Math.max(1, Math.round((current + InfiniteScrollerDirective.PAGE_VIEW_TOP_MARGIN) / this.pageHeight)) | |
85 | } | |
86 | } |