47 lines
2.1 KiB
JavaScript
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
|
|
};
|
|
};
|