@snap/camera-kit/dist/common/pageVisibility.js

Camera Kit Web

import { Injectable } from "@snap/ts-inject";
export class PageVisibility {
    constructor() {
        this.onHiddenHandlers = new Set();
        this.onVisibleHandlers = new Set();
        this.previousVisibilityState = document.visibilityState;
        this.visibilityTransition = false;
        this.onVisibilityChange = this.onVisibilityChange.bind(this);
        this.isDuringVisibilityTransition = this.isDuringVisibilityTransition.bind(this);
        this.onPageHidden = this.onPageHidden.bind(this);
        this.onPageVisible = this.onPageVisible.bind(this);
        this.destroy = this.destroy.bind(this);
        document.addEventListener("visibilitychange", this.onVisibilityChange);
    }
    isDuringVisibilityTransition(test) {
        return test === this.visibilityTransition;
    }
    onPageHidden(handler) {
        this.onHiddenHandlers.add(handler);
        return () => this.onHiddenHandlers.delete(handler);
    }
    onPageVisible(handler) {
        this.onVisibleHandlers.add(handler);
        return () => this.onVisibleHandlers.delete(handler);
    }
    destroy() {
        document.removeEventListener("visibilitychange", this.onVisibilityChange);
        this.onHiddenHandlers.clear();
        this.onVisibleHandlers.clear();
    }
    onVisibilityChange() {
        const handlers = this.previousVisibilityState === "visible" && document.visibilityState === "hidden"
            ? this.onHiddenHandlers
            : this.previousVisibilityState === "hidden" && document.visibilityState === "visible"
                ? this.onVisibleHandlers
                : new Set();
        this.visibilityTransition = document.visibilityState;
        for (const handler of handlers) {
            try {
                handler();
            }
            catch (error) {
                if (typeof window !== "undefined")
                    window.dispatchEvent(new CustomEvent("error", { detail: error }));
            }
        }
        this.previousVisibilityState = this.visibilityTransition;
        this.visibilityTransition = false;
    }
}
export const pageVisibilityFactory = Injectable("pageVisibility", () => new PageVisibility());
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