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feat(ObserveViewport): use most outer ViewportProvider
In case multiple ViewportProviders are renderd within the same page only the most outer provider should collect scroll and dimension updates to to reduce duplicate work. Issue: #3
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,271 @@ | ||
| import * as React from 'react'; | ||
| import debounce from 'lodash.debounce'; | ||
| import memoize from 'memoize-one'; | ||
| import raf from 'raf'; | ||
|
|
||
| import { | ||
| shallowEqualScroll, | ||
| shallowEqualPrivateScroll, | ||
| shallowEqualDimensions, | ||
| browserSupportsPassiveEvents, | ||
| } from './utils'; | ||
|
|
||
| import { | ||
| IDimensions, | ||
| IPrivateScroll, | ||
| IScroll, | ||
| IViewport, | ||
| IViewportCollectorUpdateOptions, | ||
| } from './types'; | ||
|
|
||
| export const SCROLL_DIR_DOWN = Symbol('SCROLL_DIR_DOWN'); | ||
| export const SCROLL_DIR_UP = Symbol('SCROLL_DIR_UP'); | ||
| export const SCROLL_DIR_LEFT = Symbol('SCROLL_DIR_LEFT'); | ||
| export const SCROLL_DIR_RIGHT = Symbol('SCROLL_DIR_RIGHT'); | ||
|
|
||
| const getNodeScroll = (elem = window) => { | ||
| let { scrollX, scrollY } = elem; | ||
| if (scrollX === undefined) { | ||
| scrollX = elem.pageXOffset; | ||
| } | ||
| if (scrollY === undefined) { | ||
| scrollY = elem.pageYOffset; | ||
| } | ||
|
|
||
| return { | ||
| x: scrollX, | ||
| y: scrollY, | ||
| }; | ||
| }; | ||
|
|
||
| const getClientDimensions = (): IDimensions => { | ||
| if (!document || !document.documentElement) { | ||
| return createEmptyDimensionState(); | ||
| } | ||
| const { innerWidth, innerHeight, outerWidth, outerHeight } = window; | ||
| const { | ||
| clientWidth, | ||
| clientHeight, | ||
| scrollHeight, | ||
| scrollWidth, | ||
| offsetHeight, | ||
| offsetWidth, | ||
| } = document.documentElement; | ||
| return { | ||
| width: innerWidth, | ||
| height: innerHeight, | ||
| clientWidth, | ||
| clientHeight, | ||
| outerWidth, | ||
| outerHeight, | ||
| documentWidth: Math.max(scrollWidth, offsetWidth, clientWidth), | ||
| documentHeight: Math.max(scrollHeight, offsetHeight, clientHeight), | ||
| }; | ||
| }; | ||
|
|
||
| const getXDir = (x: number, prev: IPrivateScroll) => { | ||
| switch (true) { | ||
| case x < prev.x: | ||
| return SCROLL_DIR_LEFT; | ||
| case x > prev.x: | ||
| return SCROLL_DIR_RIGHT; | ||
| case x === prev.x: | ||
| return prev.xDir; | ||
| default: | ||
| throw new Error('Could not calculate xDir'); | ||
| } | ||
| }; | ||
|
|
||
| const getYDir = (y: number, prev: IPrivateScroll) => { | ||
| switch (true) { | ||
| case y < prev.y: | ||
| return SCROLL_DIR_UP; | ||
| case y > prev.y: | ||
| return SCROLL_DIR_DOWN; | ||
| case y === prev.y: | ||
| return prev.yDir; | ||
| default: | ||
| throw new Error('Could not calculate yDir'); | ||
| } | ||
| }; | ||
|
|
||
| const privateToPublicScroll = ({ | ||
| yDir, | ||
| xDir, | ||
| ...scroll | ||
| }: IPrivateScroll): IScroll => { | ||
| return { | ||
| ...scroll, | ||
| isScrollingUp: yDir === SCROLL_DIR_UP, | ||
| isScrollingDown: yDir === SCROLL_DIR_DOWN, | ||
| isScrollingLeft: xDir === SCROLL_DIR_LEFT, | ||
| isScrollingRight: xDir === SCROLL_DIR_RIGHT, | ||
| }; | ||
| }; | ||
|
|
||
| const createInitPrivateScrollState = () => ({ | ||
| x: 0, | ||
| y: 0, | ||
| xDir: undefined, | ||
| yDir: undefined, | ||
| xTurn: 0, | ||
| yTurn: 0, | ||
| xDTurn: 0, | ||
| yDTurn: 0, | ||
| }); | ||
|
|
||
| const createEmptyDimensionState = (): IDimensions => ({ | ||
| width: 0, | ||
| height: 0, | ||
| clientWidth: 0, | ||
| clientHeight: 0, | ||
| outerWidth: 0, | ||
| outerHeight: 0, | ||
| documentWidth: 0, | ||
| documentHeight: 0, | ||
| }); | ||
|
|
||
| export const createInitScrollState = (): IScroll => | ||
| privateToPublicScroll(createInitPrivateScrollState()); | ||
|
|
||
| export const createInitDimensionsState = (): IDimensions => { | ||
| if (typeof window === 'undefined') { | ||
| return createEmptyDimensionState(); | ||
| } | ||
| return getClientDimensions(); | ||
| }; | ||
|
|
||
| interface IProps { | ||
| onUpdate: ( | ||
| props: IViewport, | ||
| options: IViewportCollectorUpdateOptions, | ||
| ) => void; | ||
| } | ||
|
|
||
| export default class ViewportCollector extends React.PureComponent<IProps> { | ||
| private scrollState: IPrivateScroll; | ||
| private dimensionsState: IDimensions; | ||
| private lastSyncedScrollState: IPrivateScroll; | ||
| private lastSyncedDimensionsState: IDimensions; | ||
| private tickId: NodeJS.Timer; | ||
| private componentMightHaveUpdated: boolean; | ||
|
|
||
| constructor(props: IProps) { | ||
| super(props); | ||
| this.state = { | ||
| parentProviderExists: false, | ||
| }; | ||
| this.scrollState = createInitPrivateScrollState(); | ||
| this.dimensionsState = createInitDimensionsState(); | ||
| this.lastSyncedDimensionsState = { ...this.dimensionsState }; | ||
| this.lastSyncedScrollState = { ...this.scrollState }; | ||
| } | ||
|
|
||
| componentDidMount() { | ||
| const options = browserSupportsPassiveEvents ? { passive: true } : false; | ||
| window.addEventListener('scroll', this.handleScroll, options); | ||
| window.addEventListener('resize', this.handleResize, options); | ||
| window.addEventListener('orientationchange', this.handleResize, options); | ||
|
|
||
| this.tickId = raf(this.tick); | ||
| } | ||
|
|
||
| componentWillUnmount() { | ||
| window.removeEventListener('scroll', this.handleScroll, false); | ||
| window.removeEventListener('resize', this.handleResize, false); | ||
| window.removeEventListener('orientationchange', this.handleResize, false); | ||
| raf.cancel(this.tickId); | ||
| } | ||
|
|
||
| tick = () => { | ||
| if (this) { | ||
| if (this.componentMightHaveUpdated) { | ||
| this.syncState(); | ||
| } | ||
| this.componentMightHaveUpdated = false; | ||
| this.tickId = raf(this.tick); | ||
| } | ||
| }; | ||
|
|
||
| handleScroll = () => { | ||
| const { x, y } = getNodeScroll(); | ||
| const { | ||
| xDir: prevXDir, | ||
| yDir: prevYDir, | ||
| xTurn: prevXTurn, | ||
| yTurn: prevYTurn, | ||
| } = this.scrollState; | ||
|
|
||
| this.scrollState.xDir = getXDir(x, this.scrollState); | ||
| this.scrollState.yDir = getYDir(y, this.scrollState); | ||
|
|
||
| this.scrollState.xTurn = this.scrollState.xDir === prevXDir ? prevXTurn : x; | ||
| this.scrollState.yTurn = this.scrollState.yDir === prevYDir ? prevYTurn : y; | ||
|
|
||
| this.scrollState.xDTurn = x - this.scrollState.xTurn; | ||
| this.scrollState.yDTurn = y - this.scrollState.yTurn; | ||
|
|
||
| this.scrollState.x = x; | ||
| this.scrollState.y = y; | ||
|
|
||
| this.componentMightHaveUpdated = true; | ||
| }; | ||
|
|
||
| handleResize = debounce(() => { | ||
| Object.assign(this.dimensionsState, getClientDimensions()); | ||
|
|
||
| this.componentMightHaveUpdated = true; | ||
| }, 80); | ||
|
|
||
| getPublicScroll: ((scroll: IScroll) => IScroll) = memoize( | ||
| (scroll: IScroll): IScroll => scroll, | ||
| shallowEqualScroll, | ||
| ); | ||
|
|
||
| getPublicDimensions: ((dimensions: IDimensions) => IDimensions) = memoize( | ||
| (dimensions: IDimensions): IDimensions => dimensions, | ||
| shallowEqualDimensions, | ||
| ); | ||
|
|
||
| syncState = () => { | ||
| const scrollDidUpdate = !shallowEqualPrivateScroll( | ||
| this.lastSyncedScrollState, | ||
| this.scrollState, | ||
| ); | ||
| const dimensionsDidUpdate = !shallowEqualDimensions( | ||
| this.lastSyncedDimensionsState, | ||
| this.dimensionsState, | ||
| ); | ||
|
|
||
| if (scrollDidUpdate) { | ||
| this.lastSyncedScrollState = { ...this.scrollState }; | ||
| } | ||
|
|
||
| if (dimensionsDidUpdate) { | ||
| this.lastSyncedDimensionsState = { ...this.dimensionsState }; | ||
| } | ||
|
|
||
| if (scrollDidUpdate || dimensionsDidUpdate) { | ||
| const publicState = this.getPropsFromState(); | ||
| this.props.onUpdate(publicState, { | ||
| scrollDidUpdate, | ||
| dimensionsDidUpdate, | ||
| }); | ||
| } | ||
| }; | ||
|
|
||
| getPropsFromState(): IViewport { | ||
| return { | ||
| scroll: this.getPublicScroll( | ||
| privateToPublicScroll(this.lastSyncedScrollState), | ||
| ), | ||
| dimensions: this.getPublicDimensions({ | ||
| ...this.lastSyncedDimensionsState, | ||
| }), | ||
| }; | ||
| } | ||
|
|
||
| render() { | ||
| return null; | ||
| } | ||
| } |
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