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April 19, 2020 19:32
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import * as React from 'react'; | |
import PropTypes from 'prop-types'; | |
type Props = { | |
disabled?: boolean; | |
children: React.ReactNode; | |
}; | |
export class WindowScrollContext extends React.Component<Props> { | |
// https://github.com/necolas/react-native-web/blob/master/packages/react-native-web/src/vendor/react-native/VirtualizedList/index.js#L470 | |
static childContextTypes = { | |
virtualizedList: PropTypes.shape({ | |
getScrollMetrics: PropTypes.func, | |
horizontal: PropTypes.bool, | |
getOutermostParentListRef: PropTypes.func, | |
getNestedChildState: PropTypes.func, | |
registerAsNestedChild: PropTypes.func, | |
unregisterAsNestedChild: PropTypes.func, | |
}), | |
}; | |
_nestedChildLists = new Map<string, { ref: any; state: any }>(); | |
getChildContext(): any { | |
if (this.props.disabled) { | |
return { virtualizedList: null }; | |
} | |
return { | |
virtualizedList: { | |
getScrollMetrics: this._getScrollMetrics, | |
horizontal: false, | |
getOutermostParentListRef: this._getOutermostParentListRef, | |
getNestedChildState: this._getNestedChildState, | |
registerAsNestedChild: this._registerAsNestedChild, | |
unregisterAsNestedChild: this._unregisterAsNestedChild, | |
}, | |
}; | |
} | |
componentDidMount() { | |
window.addEventListener('scroll', this._onScroll); | |
} | |
componentWillUnmount() { | |
window.removeEventListener('scroll', this._onScroll); | |
} | |
_onScroll = () => { | |
const { documentElement } = document; | |
const normalizedEvent = { | |
nativeEvent: { | |
contentOffset: { | |
x: 0, | |
y: window.pageYOffset, | |
}, | |
contentSize: { | |
height: documentElement.scrollHeight, | |
width: documentElement.scrollWidth, | |
}, | |
layoutMeasurement: { | |
height: documentElement.clientHeight, | |
width: documentElement.clientWidth, | |
}, | |
}, | |
timeStamp: Date.now(), | |
}; | |
this._nestedChildLists.forEach((childList) => { | |
childList.ref && childList.ref._onScroll(normalizedEvent); | |
}); | |
}; | |
_getScrollMetrics = () => { | |
const { documentElement } = document; | |
return { | |
visibleLength: documentElement.clientHeight, | |
contentLength: documentElement.scrollHeight, | |
dOffset: 0, | |
dt: 10, | |
offset: window.pageYOffset, | |
timestamp: Date.now(), | |
velocity: 0, | |
}; | |
}; | |
_getOutermostParentListRef = () => { | |
return { | |
getScrollRef: () => ({ | |
getNativeScrollRef: () => document.documentElement, | |
}), | |
}; | |
}; | |
_getNestedChildState = (key: string): any => { | |
const existingChildData = this._nestedChildLists.get(key); | |
return existingChildData && existingChildData.state; | |
}; | |
_registerAsNestedChild = (childList: any) => { | |
this._nestedChildLists.set(childList.key, { | |
ref: childList.ref, | |
state: null, | |
}); | |
if (childList.ref != null) { | |
childList.ref.measureLayoutRelativeToContainingList(); | |
} | |
}; | |
_unregisterAsNestedChild = (childList: { key: string; state: any }): void => { | |
this._nestedChildLists.set(childList.key, { | |
ref: null, | |
state: childList.state, | |
}); | |
}; | |
render() { | |
return this.props.children; | |
} | |
} |
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