-import { distinct, distinctUntilChanged, filter, map, share, startWith, throttleTime } from 'rxjs/operators'
-import { Directive, EventEmitter, Input, OnDestroy, OnInit, Output } from '@angular/core'
-import { fromEvent, Subscription } from 'rxjs'
+import { distinctUntilChanged, filter, map, share, startWith, tap, throttleTime } from 'rxjs/operators'
+import { AfterContentChecked, Directive, ElementRef, EventEmitter, Input, OnDestroy, OnInit, Output } from '@angular/core'
+import { fromEvent, Observable, Subscription } from 'rxjs'
@Directive({
selector: '[myInfiniteScroller]'
})
-export class InfiniteScrollerDirective implements OnInit, OnDestroy {
- @Input() containerHeight: number
- @Input() pageHeight: number
- @Input() firstLoadedPage = 1
+export class InfiniteScrollerDirective implements OnInit, OnDestroy, AfterContentChecked {
@Input() percentLimit = 70
@Input() autoInit = false
+ @Input() onItself = false
+ @Input() dataObservable: Observable<any[]>
@Output() nearOfBottom = new EventEmitter<void>()
- @Output() nearOfTop = new EventEmitter<void>()
- @Output() pageChanged = new EventEmitter<number>()
private decimalLimit = 0
private lastCurrentBottom = -1
- private lastCurrentTop = 0
private scrollDownSub: Subscription
- private scrollUpSub: Subscription
- private pageChangeSub: Subscription
- private middleScreen: number
+ private container: HTMLElement
- constructor () {
+ private checkScroll = false
+
+ constructor (private el: ElementRef) {
this.decimalLimit = this.percentLimit / 100
}
+ ngAfterContentChecked () {
+ if (this.checkScroll) {
+ this.checkScroll = false
+
+ console.log('Checking if the initial state has a scroll.')
+
+ if (this.hasScroll() === false) this.nearOfBottom.emit()
+ }
+ }
+
ngOnInit () {
if (this.autoInit === true) return this.initialize()
}
ngOnDestroy () {
if (this.scrollDownSub) this.scrollDownSub.unsubscribe()
- if (this.scrollUpSub) this.scrollUpSub.unsubscribe()
- if (this.pageChangeSub) this.pageChangeSub.unsubscribe()
}
initialize () {
- this.middleScreen = window.innerHeight / 2
+ this.container = this.onItself
+ ? this.el.nativeElement
+ : document.documentElement
// Emit the last value
const throttleOptions = { leading: true, trailing: true }
- const scrollObservable = fromEvent(window, 'scroll')
+ const scrollableElement = this.onItself ? this.container : window
+ const scrollObservable = fromEvent(scrollableElement, 'scroll')
.pipe(
- startWith(null),
+ startWith(null as string), // FIXME: typings
throttleTime(200, undefined, throttleOptions),
- map(() => ({ current: window.scrollY, maximumScroll: document.body.clientHeight - window.innerHeight })),
+ map(() => this.getScrollInfo()),
distinctUntilChanged((o1, o2) => o1.current === o2.current),
share()
)
// Scroll Down
this.scrollDownSub = scrollObservable
.pipe(
- // Check we scroll down
- filter(({ current }) => {
- const res = this.lastCurrentBottom < current
-
- this.lastCurrentBottom = current
- return res
- }),
- filter(({ current, maximumScroll }) => maximumScroll <= 0 || (current / maximumScroll) > this.decimalLimit)
+ filter(({ current }) => this.isScrollingDown(current)),
+ filter(({ current, maximumScroll }) => (current / maximumScroll) > this.decimalLimit)
)
.subscribe(() => this.nearOfBottom.emit())
- // Scroll up
- this.scrollUpSub = scrollObservable
- .pipe(
- // Check we scroll up
- filter(({ current }) => {
- const res = this.lastCurrentTop > current
-
- this.lastCurrentTop = current
- return res
- }),
- filter(({ current, maximumScroll }) => {
- return current !== 0 && (1 - (current / maximumScroll)) > this.decimalLimit
- })
- )
- .subscribe(() => this.nearOfTop.emit())
+ if (this.dataObservable) {
+ this.dataObservable
+ .pipe(filter(d => d.length !== 0))
+ .subscribe(() => this.checkScroll = true)
+ }
+ }
- // Page change
- this.pageChangeSub = scrollObservable
- .pipe(
- distinct(),
- map(({ current }) => this.calculateCurrentPage(current)),
- distinctUntilChanged()
- )
- .subscribe(res => this.pageChanged.emit(res))
+ private getScrollInfo () {
+ return { current: this.container.scrollTop, maximumScroll: this.getMaximumScroll() }
}
- private calculateCurrentPage (current: number) {
- const scrollY = current + this.middleScreen
+ private getMaximumScroll () {
+ return this.container.scrollHeight - window.innerHeight
+ }
+
+ private hasScroll () {
+ return this.getMaximumScroll() > 0
+ }
- const page = Math.max(1, Math.ceil(scrollY / this.pageHeight))
+ private isScrollingDown (current: number) {
+ const result = this.lastCurrentBottom < current
- // Offset page
- return page + (this.firstLoadedPage - 1)
+ this.lastCurrentBottom = current
+ return result
}
}