@opensig/opendesign/es/hooks/use-intersection-observer.mjs

import { isFunction } from "../_utils/is.mjs";
const defaultKey = {};
const instancePool = /* @__PURE__ */ new WeakMap();
function createObserverInstance(options) {
  let instance = instancePool.get(options || defaultKey);
  if (!instance) {
    const observer = new IntersectionObserver((entries) => {
      entries.forEach((entry) => {
        var _a;
        const ele = entry.target;
        const ins = instance == null ? void 0 : instance.elementPool.get(ele);
        if (!ins) {
          return;
        }
        (_a = ins == null ? void 0 : ins.callbacks) == null ? void 0 : _a.forEach((fn) => fn(entry, entry.isIntersecting));
      });
    }, options);
    const elementPool = /* @__PURE__ */ new WeakMap();
    instance = {
      observer,
      record: 0,
      elementPool
    };
    instancePool.set(options || defaultKey, instance);
  }
  return instance;
}
function useIntersectionObserver(options) {
  const instance = createObserverInstance(options);
  return {
    /**
     * 监听实例
     */
    observer: instance.observer,
    /**
     * 创建监听实例
     * el: 添加监听的元素
     * listener: 进入视口回调, 移除监听时需要指定该监听函数
     */
    observe: (el, listener) => {
      if (!el || !isFunction(listener)) {
        return null;
      }
      const val = instance.elementPool.get(el);
      if (val) {
        val.callbacks.push(listener);
      } else {
        instance.observer.observe(el);
        instance.record++;
        instance.elementPool.set(el, {
          element: el,
          callbacks: [listener]
        });
      }
      return instance.observer;
    },
    /**
     * 移除对某元素的监听
     * el: 要移除监听的元素
     * listener: 要移除的监听函数，如果不传，则使用初始化时的回调
     */
    unobserve: (el, listener) => {
      if (!el || !isFunction(listener) || !instance) {
        return;
      }
      const val = instance.elementPool.get(el);
      if (val) {
        const idx = val.callbacks.indexOf(listener);
        val.callbacks.splice(idx, 1);
        if (val.callbacks.length === 0) {
          instance.observer.unobserve(el);
          instance.elementPool.delete(el);
          instance.record--;
          if (instance.record === 0) {
            instance.observer.disconnect();
          }
        }
      }
    },
    /**
     * 销毁观察器
     */
    destroy() {
      instance.observer.disconnect();
    }
  };
}
export {
  useIntersectionObserver
};