react-virtualized-compat
Version:
Fork from `react-virtual` with react 19 compatability
33 lines (31 loc) • 1.42 kB
JavaScript
/*:: import type {OverscanIndicesGetterParams, OverscanIndices} from './types';*/
export var SCROLL_DIRECTION_BACKWARD = -1;
export var SCROLL_DIRECTION_FORWARD = 1;
export var SCROLL_DIRECTION_HORIZONTAL = 'horizontal';
export var SCROLL_DIRECTION_VERTICAL = 'vertical';
/**
* Calculates the number of cells to overscan before and after a specified range.
* This function ensures that overscanning doesn't exceed the available cells.
*/
export default function defaultOverscanIndicesGetter(_ref /*:: */) /*: OverscanIndices*/{
var cellCount = _ref /*:: */.cellCount,
overscanCellsCount = _ref /*:: */.overscanCellsCount,
scrollDirection = _ref /*:: */.scrollDirection,
startIndex = _ref /*:: */.startIndex,
stopIndex = _ref /*:: */.stopIndex;
// Make sure we render at least 1 cell extra before and after (except near boundaries)
// This is necessary in order to support keyboard navigation (TAB/SHIFT+TAB) in some cases
// For more info see issues #625
overscanCellsCount = Math.max(1, overscanCellsCount);
if (scrollDirection === SCROLL_DIRECTION_FORWARD) {
return {
overscanStartIndex: Math.max(0, startIndex - 1),
overscanStopIndex: Math.min(cellCount - 1, stopIndex + overscanCellsCount)
};
} else {
return {
overscanStartIndex: Math.max(0, startIndex - overscanCellsCount),
overscanStopIndex: Math.min(cellCount - 1, stopIndex + 1)
};
}
}