Outlook_Addin_LLM/node_modules/@fluentui/react-virtualizer/lib/hooks/useVirtualizerMeasure.js

47 lines
2.1 KiB
JavaScript

import * as React from 'react';
import { useResizeObserverRef_unstable } from './useResizeObserverRef';
/**
* React hook that measures virtualized space based on a static size to ensure optimized virtualization length.
*/ export const useStaticVirtualizerMeasure = (virtualizerProps)=>{
const { defaultItemSize, direction = 'vertical' } = virtualizerProps;
const [state, setState] = React.useState({
virtualizerLength: 0,
bufferSize: 0,
bufferItems: 0
});
const { virtualizerLength, bufferItems, bufferSize } = state;
const resizeCallback = React.useCallback((_entries, // TODO: exclude types from this lint rule: https://github.com/microsoft/fluentui/issues/31286
// eslint-disable-next-line no-restricted-globals
_observer, scrollRef)=>{
if (!(scrollRef === null || scrollRef === void 0 ? void 0 : scrollRef.current)) {
return;
}
const containerSize = direction === 'vertical' ? scrollRef === null || scrollRef === void 0 ? void 0 : scrollRef.current.getBoundingClientRect().height : scrollRef === null || scrollRef === void 0 ? void 0 : scrollRef.current.getBoundingClientRect().width;
/*
* Number of items required to cover viewport.
*/ const length = Math.ceil(containerSize / defaultItemSize + 1);
/*
* Number of items to append at each end, i.e. 'preload' each side before entering view.
*/ const newBufferItems = Math.max(Math.floor(length / 4), 2);
/*
* This is how far we deviate into the bufferItems to detect a redraw.
*/ const newBufferSize = Math.max(Math.floor(length / 8 * defaultItemSize), 1);
const totalLength = length + newBufferItems * 2 + 1;
setState({
virtualizerLength: totalLength,
bufferItems: newBufferItems,
bufferSize: newBufferSize
});
}, [
defaultItemSize,
direction
]);
const scrollRef = useResizeObserverRef_unstable(resizeCallback);
return {
virtualizerLength,
bufferItems,
bufferSize,
scrollRef
};
};