{"version":3,"file":"follow-value.mjs","sources":["../../../src/value/follow-value.ts"],"sourcesContent":["import { MotionValue, motionValue } from \".\"\nimport { JSAnimation } from \"../animation/JSAnimation\"\nimport { AnyResolvedKeyframe, ValueAnimationTransition } from \"../animation/types\"\nimport { frame } from \"../frameloop\"\nimport { isMotionValue } from \"./utils/is-motion-value\"\n\n/**\n * Options for useFollowValue hook, extending ValueAnimationTransition\n * but excluding lifecycle callbacks that don't make sense for the hook pattern.\n */\nexport type FollowValueOptions = Omit<\n    ValueAnimationTransition,\n    \"onUpdate\" | \"onComplete\" | \"onPlay\" | \"onRepeat\" | \"onStop\"\n> & {\n    /**\n     * When true, the first change from a tracked `MotionValue` source\n     * will jump to the new value instead of animating. Subsequent\n     * changes animate normally. This prevents unwanted animations\n     * on page refresh or back navigation (e.g. `useScroll` + `useSpring`).\n     *\n     * @default false\n     */\n    skipInitialAnimation?: boolean\n}\n\n/**\n * Create a `MotionValue` that animates to its latest value using any transition type.\n * Can either be a value or track another `MotionValue`.\n *\n * ```jsx\n * const x = motionValue(0)\n * const y = followValue(x, { type: \"spring\", stiffness: 300 })\n * // or with tween\n * const z = followValue(x, { type: \"tween\", duration: 0.5, ease: \"easeOut\" })\n * ```\n *\n * @param source - Initial value or MotionValue to track\n * @param options - Animation transition options\n * @returns `MotionValue`\n *\n * @public\n */\nexport function followValue<T extends AnyResolvedKeyframe>(\n    source: T | MotionValue<T>,\n    options?: FollowValueOptions\n) {\n    const initialValue = isMotionValue(source) ? source.get() : source\n    const value = motionValue(initialValue)\n\n    attachFollow(value, source, options)\n\n    return value\n}\n\n/**\n * Attach an animation to a MotionValue that will animate whenever the value changes.\n * Similar to attachSpring but supports any transition type (spring, tween, inertia, etc.)\n *\n * @param value - The MotionValue to animate\n * @param source - Initial value or MotionValue to track\n * @param options - Animation transition options\n * @returns Cleanup function\n *\n * @public\n */\nexport function attachFollow<T extends AnyResolvedKeyframe>(\n    value: MotionValue<T>,\n    source: T | MotionValue<T>,\n    options: FollowValueOptions = {}\n): VoidFunction {\n    const initialValue = value.get()\n\n    let activeAnimation: JSAnimation<number> | null = null\n    let latestValue = initialValue\n    let latestSetter: (v: T) => void\n\n    const unit =\n        typeof initialValue === \"string\"\n            ? initialValue.replace(/[\\d.-]/g, \"\")\n            : undefined\n\n    const stopAnimation = () => {\n        if (activeAnimation) {\n            activeAnimation.stop()\n            activeAnimation = null\n        }\n    }\n\n    const startAnimation = () => {\n        const currentValue = asNumber(value.get())\n        const targetValue = asNumber(latestValue)\n\n        // Don't animate if we're already at the target\n        if (currentValue === targetValue) {\n            stopAnimation()\n            return\n        }\n\n        // Use the running animation's analytical velocity for accuracy,\n        // falling back to the MotionValue's velocity for the initial animation.\n        // This prevents systematic velocity loss at high frame rates (240hz+).\n        const velocity = activeAnimation\n            ? activeAnimation.getGeneratorVelocity()\n            : value.getVelocity()\n\n        stopAnimation()\n\n        activeAnimation = new JSAnimation({\n            keyframes: [currentValue, targetValue],\n            velocity,\n            // Default to spring if no type specified (matches useSpring behavior)\n            type: \"spring\",\n            restDelta: 0.001,\n            restSpeed: 0.01,\n            ...options,\n            onUpdate: latestSetter,\n        })\n    }\n\n    // Use a stable function reference so the frame loop Set deduplicates\n    // multiple calls within the same frame (e.g. rapid mouse events)\n    const scheduleAnimation = () => {\n        startAnimation()\n        value[\"events\"].animationStart?.notify()\n        activeAnimation?.then(() => {\n            value[\"events\"].animationComplete?.notify()\n        })\n    }\n\n    value.attach((v, set) => {\n        latestValue = v\n        latestSetter = (latest) => set(parseValue(latest, unit) as T)\n        frame.postRender(scheduleAnimation)\n    }, stopAnimation)\n\n    if (isMotionValue(source)) {\n        let skipNextAnimation = options.skipInitialAnimation === true\n\n        const removeSourceOnChange = source.on(\"change\", (v) => {\n            if (skipNextAnimation) {\n                skipNextAnimation = false\n                value.jump(parseValue(v, unit) as T, false)\n            } else {\n                value.set(parseValue(v, unit) as T)\n            }\n        })\n\n        const removeValueOnDestroy = value.on(\"destroy\", removeSourceOnChange)\n\n        return () => {\n            removeSourceOnChange()\n            removeValueOnDestroy()\n        }\n    }\n\n    return stopAnimation\n}\n\nfunction parseValue(v: AnyResolvedKeyframe, unit?: string) {\n    return unit ? 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