46b6767c
 刘淇
init 提交到库
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export const mapVirtualToProps = ({
items,
itemHeight
}, {
startIndex,
endIndex
}) => {
const visibleItems = endIndex > -1 ? items.slice(startIndex, endIndex + 1) : []
// style
const height = items.length * itemHeight
const paddingTop = startIndex * itemHeight
return {
items: visibleItems,
style: `height: ${height}px; padding-top: ${paddingTop}px; box-sizing: border-box;`
}
}
export const getVisibleItemBounds = (viewTop, viewHeight, itemCount, itemHeight, itemBuffer) => {
// visible list inside view
const listViewTop = Math.max(0, viewTop)
// visible item indexes
const startIndex = Math.max(0, Math.floor(listViewTop / itemHeight) - 12)
const endIndex = Math.min(startIndex + Math.ceil(viewHeight / itemHeight) + itemBuffer - 1, itemCount)
return {
startIndex,
endIndex,
}
}
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