import type { PositionStrategy } from './strategy';
/**
 * Position lookups over fully heterogeneous sizes: one prefix-sum array entry per item, where
 * `prefixSum[i]` is the summed size of items `0..i-1`. Building walks every item once (O(n) time
 * and memory); offset reads are O(1) and offset-to-index lookups are an O(log n) binary search.
 * This is the general fallback when neither the uniform nor the sparse strategy applies (per-item
 * size settings or a size-modifying hook exist).
 */
export declare class PrefixSumPositionStrategy implements PositionStrategy {
    #private;
    /**
     * The prefix sum array. `prefixSum[0] = 0`, `prefixSum[n]` = total size of all `n` items.
     *
     * @type {Float64Array}
     */
    readonly prefixSum: Float64Array;
    /**
     * @param {number} totalItems The total item count read at build time.
     * @param {Function} sizeFn A function that returns the size for a given index.
     * @param {number} defaultSize The default size for items that report NaN.
     */
    constructor(totalItems: number, sizeFn: (index: number) => number, defaultSize: number);
    /**
     * Returns the cumulative size before the given item index.
     *
     * @param {number} index The item index.
     * @returns {number} The cumulative size before this index.
     */
    getOffset(index: number): number;
    /**
     * Finds the item index at a given pixel offset using binary search over the prefix sums.
     *
     * @param {number} offset The pixel offset.
     * @returns {number} The index whose cumulative start position is at or just before the offset.
     */
    findIndexAtOffset(offset: number): number;
    /**
     * Returns the size of the single item at the given index.
     *
     * @param {number} index The item index.
     * @returns {number} The size (difference between consecutive prefix sums), or `0` outside the
     *   item range.
     */
    getSizeAt(index: number): number;
    /**
     * Returns the total size of all items.
     *
     * @returns {number}
     */
    getTotalSize(): number;
}