PositionManager

The internal segment tree exposed for advanced use cases. Stores row heights and answers prefix-sum queries in O(log n).

import { PositionManager } from 'vue-virtual-scroller-kit'

const manager = new PositionManager(
  10_000, // item count
  50, // uniform estimated height (or a function (index) => number)
)

Use PositionManager when building completely custom virtualised layouts that don't fit the provided components.

Methods

totalSize

Total height of all items.

getOffset(index)

Pixel offset of item i = sum of heights [0..i-1].

getHeight(index)

Stored height of item i.

findIndex(scrollTop)

First item index visible at scrollTop.

set(index, height)

Update measured height, O(log n).

manager.totalSize // total height of all items
manager.getOffset(index) // pixel offset of item i = sum of heights[0..i-1]
manager.getHeight(index) // stored height of item i
manager.findIndex(scrollTop) // first item index visible at scrollTop
manager.set(index, height) // update measured height, O(log n)