@mornya/react-image-libs/esm/IntersectObserverContext.js

The project of React.js Image library.

var __read = (this && this.__read) || function (o, n) {
    var m = typeof Symbol === "function" && o[Symbol.iterator];
    if (!m) return o;
    var i = m.call(o), r, ar = [], e;
    try {
        while ((n === void 0 || n-- > 0) && !(r = i.next()).done) ar.push(r.value);
    }
    catch (error) { e = { error: error }; }
    finally {
        try {
            if (r && !r.done && (m = i["return"])) m.call(i);
        }
        finally { if (e) throw e.error; }
    }
    return ar;
};
import { jsx as _jsx } from "react/jsx-runtime";
import { createContext, useContext, useState, useEffect } from 'react';
import { ImageObserver } from './ImageObserver';
export var IntersectObserverContext = createContext({
    subscribe: function () {
        console.error('To use components such as <LazyImage> or <LazyBackground>, must be initialized the provider: <IntersectObserverProvider>.');
    },
    unsubscribe: function () { },
});
export var IntersectObserverProvider = function (props) {
    var _a = __read(useState(), 2), imageObserver = _a[0], setImageObserver = _a[1];
    var subscribe = function (target, callback, once) {
        if (imageObserver) {
            if (once) {
                imageObserver.subscribeOnce(target, callback);
            }
            else {
                var unsubscriber = imageObserver.subscribe(target, callback);
                target.addEventListener('unsubscribeImageObserverItem', unsubscriber, { once: true, capture: false });
            }
        }
    };
    var unsubscribe = function (target) {
        if (imageObserver) {
            target.dispatchEvent(new CustomEvent('unsubscribeImageObserverItem'));
            imageObserver.unsubscribe(target);
        }
    };
    useEffect(function () {
        if (!imageObserver) {
            setImageObserver(new ImageObserver.Provider(props.option));
        }
        return function () {
            imageObserver === null || imageObserver === void 0 ? void 0 : imageObserver.destroy();
        };
    }, [imageObserver, props.option]);
    return (_jsx(IntersectObserverContext.Provider, { value: { subscribe: subscribe, unsubscribe: unsubscribe }, children: imageObserver ? props.children : null }));
};
export function useIntersectObserver() {
    return useContext(IntersectObserverContext);
}