react-use-motion-measure/dist/web.js

measure view bounds

import { useRef, useEffect, useMemo } from 'react';
import createDebounce from 'debounce';
import { useMotionValue } from 'motion/react';

function useMotionMeasure(_temp) {
  let {
    debounce,
    scroll,
    polyfill,
    offsetSize
  } = _temp === void 0 ? {
    debounce: 0,
    scroll: false,
    offsetSize: false
  } : _temp;
  const ResizeObserver = polyfill || (typeof window === 'undefined' ? class ResizeObserver {} : window.ResizeObserver);
  if (!ResizeObserver) {
    throw new Error('This browser does not support ResizeObserver out of the box. See: https://github.com/OlegWock/react-use-motion-measure/#resize-observer-polyfills');
  }
  const left = useMotionValue(0);
  const top = useMotionValue(0);
  const width = useMotionValue(0);
  const height = useMotionValue(0);
  const bottom = useMotionValue(0);
  const right = useMotionValue(0);
  const x = useMotionValue(0);
  const y = useMotionValue(0);

  // keep all state in a ref
  const state = useRef({
    element: null,
    measuredAtLeastOnce: false,
    scrollContainers: null,
    resizeObserver: null,
    lastBounds: getLastBounds()
  });

  // set actual debounce values early, so effects know if they should react accordingly
  const scrollDebounce = debounce ? typeof debounce === 'number' ? debounce : debounce.scroll : null;
  const resizeDebounce = debounce ? typeof debounce === 'number' ? debounce : debounce.resize : null;

  // make sure to update state only as long as the component is truly mounted
  const mounted = useRef(false);
  useEffect(() => {
    mounted.current = true;
    return () => void (mounted.current = false);
  });

  // memoize handlers, so event-listeners know when they should update
  const [forceRefresh, resizeChange, scrollChange] = useMemo(() => {
    const callback = () => {
      if (!state.current.element) return;
      const {
        left,
        top,
        width,
        height,
        bottom,
        right,
        x,
        y
      } = state.current.element.getBoundingClientRect();
      const size = {
        left,
        top,
        width,
        height,
        bottom,
        right,
        x,
        y
      };
      if (state.current.element instanceof HTMLElement && offsetSize) {
        size.height = state.current.element.offsetHeight;
        size.width = state.current.element.offsetWidth;
      }
      Object.freeze(size);
      if (mounted.current && !areBoundsEqual(state.current.lastBounds, size)) {
        if (state.current.measuredAtLeastOnce) {
          set(state.current.lastBounds = size);
        } else {
          jump(state.current.lastBounds = size);
        }
      }
    };
    return [callback, resizeDebounce ? createDebounce(callback, resizeDebounce) : callback, scrollDebounce ? createDebounce(callback, scrollDebounce) : callback];
  }, [set, jump, offsetSize, scrollDebounce, resizeDebounce]);

  // cleanup current scroll-listeners / observers
  function removeListeners() {
    if (state.current.scrollContainers) {
      state.current.scrollContainers.forEach(element => element.removeEventListener('scroll', scrollChange, true));
      state.current.scrollContainers = null;
    }
    if (state.current.resizeObserver) {
      state.current.resizeObserver.disconnect();
      state.current.resizeObserver = null;
    }
  }

  // add scroll-listeners / observers
  function addListeners() {
    if (!state.current.element) return;
    state.current.resizeObserver = new ResizeObserver(scrollChange);
    state.current.resizeObserver.observe(state.current.element);
    if (scroll && state.current.scrollContainers) {
      state.current.scrollContainers.forEach(scrollContainer => scrollContainer.addEventListener('scroll', scrollChange, {
        capture: true,
        passive: true
      }));
    }
  }
  function getLastBounds() {
    return {
      left: left.get(),
      top: top.get(),
      width: width.get(),
      height: height.get(),
      bottom: bottom.get(),
      right: right.get(),
      x: x.get(),
      y: y.get()
    };
  }
  function set(bounds) {
    left.set(bounds.left);
    top.set(bounds.top);
    width.set(bounds.width);
    height.set(bounds.height);
    bottom.set(bounds.bottom);
    right.set(bounds.right);
    x.set(bounds.x);
    y.set(bounds.y);
  }
  function jump(bounds) {
    left.jump(bounds.left);
    top.jump(bounds.top);
    width.jump(bounds.width);
    height.jump(bounds.height);
    bottom.jump(bounds.bottom);
    right.jump(bounds.right);
    x.jump(bounds.x);
    y.jump(bounds.y);
  }

  // the ref we expose to the user
  const ref = node => {
    if (!node || node === state.current.element) return;
    removeListeners();
    state.current.element = node;
    state.current.measuredAtLeastOnce = false;
    state.current.scrollContainers = findScrollContainers(node);
    addListeners();
  };

  // add general event listeners
  useOnWindowScroll(scrollChange, Boolean(scroll));
  useOnWindowResize(resizeChange);

  // respond to changes that are relevant for the listeners
  useEffect(() => {
    removeListeners();
    addListeners();
  }, [scroll, scrollChange, resizeChange]);

  // remove all listeners when the components unmounts
  useEffect(() => removeListeners, []);
  return [ref, {
    left,
    top,
    width,
    height,
    bottom,
    right,
    x,
    y
  }, forceRefresh];
}

// Adds native resize listener to window
function useOnWindowResize(onWindowResize) {
  useEffect(() => {
    const cb = onWindowResize;
    window.addEventListener('resize', cb);
    return () => void window.removeEventListener('resize', cb);
  }, [onWindowResize]);
}
function useOnWindowScroll(onScroll, enabled) {
  useEffect(() => {
    if (enabled) {
      const cb = onScroll;
      window.addEventListener('scroll', cb, {
        capture: true,
        passive: true
      });
      return () => void window.removeEventListener('scroll', cb, true);
    }
  }, [onScroll, enabled]);
}

// Returns a list of scroll offsets
function findScrollContainers(element) {
  const result = [];
  if (!element || element === document.body) return result;
  const {
    overflow,
    overflowX,
    overflowY
  } = window.getComputedStyle(element);
  if ([overflow, overflowX, overflowY].some(prop => prop === 'auto' || prop === 'scroll')) result.push(element);
  return [...result, ...findScrollContainers(element.parentElement)];
}

// Checks if element boundaries are equal
const keys = ['x', 'y', 'top', 'bottom', 'left', 'right', 'width', 'height'];
const areBoundsEqual = (a, b) => keys.every(key => a[key] === b[key]);

export { useMotionMeasure as default };