recharts/types/cartesian/useAnimatedLineLength.d.ts

React charts

/**
 * Tracks the animated visible length of a Line's SVG path across data changes.
 *
 * Invariants:
 * 1. The visible length only grows (monotonically non-decreasing with animationElapsedTime).
 * 2. The visible length changes continuously — no jumps when data changes mid-animation.
 *    This is achieved by tracking the maximum animated length in pixels and using it
 *    as the starting point for the next animation.
 * 3. Once the line reaches 100% visibility, it never becomes partially visible again.
 *    In that case the hook returns `null`, meaning no animation stroke-dasharray is needed.
 *
 * @param points The current set of points for the line. When this reference changes,
 *   the hook detects a data change and starts a new animation from the current visible length.
 * @returns A stable callback `(animationElapsedTime, totalLength) => number | null` where:
 *   - `animationElapsedTime` is the animation progress (0 to 1)
 *   - `totalLength` is the current total length of the SVG path in pixels
 *   - returns the visible length in pixels, or `null` if the line is fully visible
 */
export declare function useAnimatedLineLength(points: unknown): (animationElapsedTime: number, totalLength: number) => number | null;