antd-mobile/2x/es/utils/use-lock-scroll.js

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import { useTouch } from './use-touch';
import { useEffect } from 'react';
import { getScrollParent } from './get-scroll-parent';
import { supportsPassive } from './supports-passive';
let totalLockCount = 0;
const BODY_LOCK_CLASS = 'adm-overflow-hidden'; // 移植自vant：https://github.com/youzan/vant/blob/HEAD/src/composables/use-lock-scroll.ts

export function useLockScroll(rootRef, shouldLock) {
  const touch = useTouch();

  const onTouchMove = event => {
    touch.move(event);
    const direction = touch.deltaY.current > 0 ? '10' : '01';
    const el = getScrollParent(event.target, rootRef.current);
    if (!el) return;
    const {
      scrollHeight,
      offsetHeight,
      scrollTop
    } = el;
    let status = '11';

    if (scrollTop === 0) {
      status = offsetHeight >= scrollHeight ? '00' : '01';
    } else if (scrollTop + offsetHeight >= scrollHeight) {
      status = '10';
    }

    if (status !== '11' && touch.isVertical() && !(parseInt(status, 2) & parseInt(direction, 2))) {
      if (event.cancelable) {
        event.preventDefault();
      }
    }
  };

  const lock = () => {
    document.addEventListener('touchstart', touch.start);
    document.addEventListener('touchmove', onTouchMove, supportsPassive ? {
      passive: false
    } : false);

    if (!totalLockCount) {
      document.body.classList.add(BODY_LOCK_CLASS);
    }

    totalLockCount++;
  };

  const unlock = () => {
    if (totalLockCount) {
      document.removeEventListener('touchstart', touch.start);
      document.removeEventListener('touchmove', onTouchMove);
      totalLockCount--;

      if (!totalLockCount) {
        document.body.classList.remove(BODY_LOCK_CLASS);
      }
    }
  };

  useEffect(() => {
    if (shouldLock) {
      lock();
      return () => {
        unlock();
      };
    }
  }, [shouldLock]);
}