import { BubbleState } from '../../models/internal/bubble-state';
import { EasingFn } from '../../models/public/configuration';
/** Standard easing functions. */
export declare const Easing: {
    linear: (t: number) => number;
    easeInOutCubic: (t: number) => number;
    easeOutCubic: (t: number) => number;
    easeInCubic: (t: number) => number;
};
/**
 * Steps the position/radius tween for a single bubble toward its physics target.
 * Writes to renderX, renderY, renderRadius, tweenProgress.
 * Syncs render fields to physics fields when tween completes.
 *
 * @param b - BubbleState to update
 * @param easingFn - Easing function (default: easeInOutCubic)
 * @returns true if tween is still active, false if complete
 */
export declare function stepTween(b: BubbleState, easingFn?: EasingFn): boolean;
/**
 * Steps the renderScale for a single bubble toward targetScale.
 * Uses lerp with hoverEase factor for smooth hover animation.
 *
 * @param b - BubbleState to update
 * @param hoverEase - Lerp factor (default: 0.10)
 * @returns true if scale is still animating, false if settled
 */
export declare function stepScale(b: BubbleState, hoverEase?: number): boolean;
/**
 * Initializes a new bubble for entry animation.
 * Sets renderScale = 0, targetScale = 1, tweenProgress = 0.
 * Call this when a bubble is first added to the chart.
 */
export declare function initBubbleEntry(b: BubbleState): void;
/**
 * Prepares a bubble for a position/radius transition (after chart.update()).
 * Captures current render position as tweenFrom.
 */
export declare function initBubbleTransition(b: BubbleState, newX: number, newY: number, newRadius: number): void;