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Commit | Line | Data |
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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 | 7 | import 'rxjs/add/operator/startWith' |
a9ca764e | 8 | import 'rxjs/add/operator/throttleTime' |
0cd4344f | 9 | import { fromEvent } from 'rxjs/observable/fromEvent' |
6a6d92b1 | 10 | import 'rxjs/add/operator/share' |
0cd4344f C |
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 () { | |
6a6d92b1 | 40 | // Emit the last value |
2c6bbd97 | 41 | const throttleOptions = { leading: true, trailing: true } |
6a6d92b1 | 42 | |
0cd4344f C |
43 | const scrollObservable = fromEvent(window, 'scroll') |
44 | .startWith(true) | |
6a6d92b1 | 45 | .throttleTime(200, undefined, throttleOptions) |
0cd4344f | 46 | .map(() => ({ current: window.scrollY, maximumScroll: document.body.clientHeight - window.innerHeight })) |
2c6bbd97 | 47 | .distinctUntilChanged((o1, o2) => o1.current === o2.current) |
6a6d92b1 | 48 | .share() |
0cd4344f C |
49 | |
50 | // Scroll Down | |
51 | scrollObservable | |
52 | // Check we scroll down | |
53 | .filter(({ current }) => { | |
54 | const res = this.lastCurrentBottom < current | |
55 | ||
56 | this.lastCurrentBottom = current | |
57 | return res | |
58 | }) | |
59 | .filter(({ current, maximumScroll }) => maximumScroll <= 0 || (current / maximumScroll) > this.decimalLimit) | |
0cd4344f C |
60 | .subscribe(() => this.nearOfBottom.emit()) |
61 | ||
62 | // Scroll up | |
63 | scrollObservable | |
64 | // Check we scroll up | |
65 | .filter(({ current }) => { | |
66 | const res = this.lastCurrentTop > current | |
67 | ||
68 | this.lastCurrentTop = current | |
69 | return res | |
70 | }) | |
71 | .filter(({ current, maximumScroll }) => { | |
72 | return current !== 0 && (1 - (current / maximumScroll)) > this.decimalLimit | |
73 | }) | |
0cd4344f C |
74 | .subscribe(() => this.nearOfTop.emit()) |
75 | ||
76 | // Page change | |
77 | scrollObservable | |
0cd4344f | 78 | .distinct() |
6a6d92b1 | 79 | .map(({ current }) => this.calculateCurrentPage(current)) |
0cd4344f C |
80 | .distinctUntilChanged() |
81 | .subscribe(res => this.pageChanged.emit(res)) | |
82 | } | |
83 | ||
6a6d92b1 C |
84 | private calculateCurrentPage (current: number) { |
85 | return Math.max(1, Math.round((current + InfiniteScrollerDirective.PAGE_VIEW_TOP_MARGIN) / this.pageHeight)) | |
86 | } | |
0cd4344f | 87 | } |