xfy
c1610ace99
overlay inherited opacity:1 from .lightbox-overlay CSS, so the moment it was appended to the DOM it painted a full-opacity black background. this showed for ~24ms (the time until the image loaded and start() ran the first frame that sets opacity 0), visible as a black flash before the fade-in. set overlay.style.opacity = '0' right after creating it, so it is transparent when appended; start()'s transition then fades it to 1 as intended.
541 lines
18 KiB
JavaScript
541 lines
18 KiB
JavaScript
(function () {
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"use strict";
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// ============ 工具函数 ============
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function prefersReducedMotion() {
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return (
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window.matchMedia &&
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window.matchMedia("(prefers-reduced-motion: reduce)").matches
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);
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}
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// 读取元素当前在视口里的 rect（用于飞行起点/终点）。
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// 统一映射成 {x,y,w,h}：getBoundingClientRect 返回的 DOMRect 用
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// left/top/width/height，而 fitCentered/transformFor 用 x/y/w/h，
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// 这里转成一致格式，避免 .w 读到 undefined。
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function rectOf(el) {
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var r = el.getBoundingClientRect();
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return {
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x: r.left,
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y: r.top,
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w: r.width,
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h: r.height,
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};
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}
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// 计算图片在视口居中、contain 适配后的目标 rect。
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// naturalW/H: 图片真实像素尺寸；vw/vh: 视口尺寸。
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function fitCentered(naturalW, naturalH, vw, vh) {
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var maxW = vw * 0.92;
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var maxH = vh * 0.88;
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var scale = Math.min(maxW / naturalW, maxH / naturalH, 1);
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var w = naturalW * scale;
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var h = naturalH * scale;
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return {
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x: (vw - w) / 2,
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y: (vh - h) / 2,
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w: w,
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h: h,
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};
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}
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// 把目标 rect 转成 transform 字符串。
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// baseW/baseH 是 img 元素的布局尺寸（=居中目标尺寸），scale 相对它缩放。
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// transform-origin 为 top left（见 CSS），translate 到 rect 左上角后 scale。
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// - 居中态：scale=1（base 就是居中尺寸）
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// - originRect 态：scale = originRect.w / base.w（缩小）
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function transformFor(rect, baseW, baseH) {
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var sx = baseW > 0 ? rect.w / baseW : 1;
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var sy = baseH > 0 ? rect.h / baseH : 1;
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return (
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"translate(" +
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rect.x +
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"px," +
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rect.y +
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"px) scale(" +
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sx +
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"," +
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sy +
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")"
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);
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}
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// 原图 URL = data-src 去 query。data-src 形如 "/uploads/x.webp?w=800"。
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function originalUrl(dataSrc) {
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return (dataSrc || "").split("?")[0];
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}
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// ============ 懒加载 ============
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// 为单个 .blur-img 容器初始化高清图懒加载。
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// IO 进入视口后把 data-src 写入 src，加载完成加 is-loaded 触发 CSS 淡入。
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function initLazyLoad(container) {
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var fullImg = container.querySelector(".blur-img-full");
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if (!fullImg) return;
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if (container.getAttribute("data-blur-init")) return;
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container.setAttribute("data-blur-init", "true");
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var fullSrc = fullImg.getAttribute("data-src");
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if (!fullSrc) return;
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var onFullLoaded = function () {
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// 给容器加 is-loaded，CSS 据此显式隐藏 placeholder。
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// 直接把 full 层 opacity 设为 1（清掉 transition），不依赖 CSS 的 opacity
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// 过渡：合成层重绘时机不稳定，可能导致 full 层卡在 opacity:0，直到一次
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// 强制重排才更新。
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container.classList.add("is-loaded");
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fullImg.style.transition = "none";
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fullImg.style.opacity = "1";
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};
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fullImg.addEventListener("load", onFullLoaded);
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// 缓存兜底：若设 src 时图片已在缓存（load 几乎立即触发，可能早于监听注册），
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// 用 complete 补一次。注意无 src 的 img complete 也为 true，故先判 src。
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if (fullImg.getAttribute("src") && fullImg.complete) {
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onFullLoaded();
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}
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if ("IntersectionObserver" in window) {
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var io = new IntersectionObserver(
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function (entries) {
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entries.forEach(function (entry) {
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if (entry.isIntersecting) {
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fullImg.src = fullSrc;
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io.unobserve(container);
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}
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});
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},
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{ rootMargin: "200px" }
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);
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io.observe(container);
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} else {
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fullImg.src = fullSrc;
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}
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}
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// ============ 图像收集 ============
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// 收集所有 selectors命中的 .blur-img 节点。
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// gallery: 正文图（组成图集）；singles: 带 lightbox-single class 的单张图（如封面）。
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function collectImages(roots) {
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var gallery = [];
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var singles = [];
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for (var i = 0; i < roots.length; i++) {
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var nodes = roots[i].querySelectorAll(".blur-img");
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for (var j = 0; j < nodes.length; j++) {
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var n = nodes[j];
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if (n.classList.contains("lightbox-single")) {
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singles.push(n);
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} else {
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gallery.push(n);
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}
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}
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}
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return { gallery: gallery, singles: singles };
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}
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// ============ 灯箱状态与开/关 ============
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// 当前灯箱状态（同时只允许一个灯箱）。
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var state = null;
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function openLightbox(originNode, gallery, index) {
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if (state) closeLightbox(true);
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var fullImg = originNode.querySelector(".blur-img-full");
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if (!fullImg) return;
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var dataSrc = fullImg.getAttribute("data-src") || "";
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var origSrc = originalUrl(dataSrc);
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var altText = fullImg.getAttribute("alt") || "";
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var isSingle =
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originNode.classList.contains("lightbox-single") ||
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gallery.length === 0;
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var vw = window.innerWidth;
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var vh = window.innerHeight;
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// 建 DOM
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var overlay = document.createElement("div");
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overlay.className = "lightbox-overlay";
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overlay.setAttribute("role", "dialog");
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overlay.setAttribute("aria-modal", "true");
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overlay.setAttribute("aria-label", "图片预览");
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overlay.setAttribute("tabindex", "-1");
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// 创建后立即设 opacity 0：append 到 DOM 时是透明的，避免在图片加载期间
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// （start() 执行前）显示全黑背景造成闪烁。start() 的渐变会把 opacity 升到 1。
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overlay.style.opacity = "0";
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var img = document.createElement("img");
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img.className = "lightbox-img";
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img.setAttribute("alt", altText);
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// 加载前先占 0 尺寸，避免原图（可能数千 px）在加载期间撑大文档
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// 可滚动区、触发非预期的 scroll 事件。start() 拿到 natural 尺寸后再设真实值。
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img.style.width = "0px";
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img.style.height = "0px";
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var caption = document.createElement("figcaption");
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caption.className = "lightbox-caption";
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caption.textContent = altText;
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if (!altText) caption.style.display = "none";
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var counter = document.createElement("div");
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counter.className = "lightbox-counter";
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if (isSingle || gallery.length === 0) {
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counter.style.display = "none";
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} else {
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counter.textContent = index + 1 + " / " + gallery.length;
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}
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// 图集模式（>1 张）才加左右导航箭头；单张不显示。
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var prevBtn = null;
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var nextBtn = null;
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if (!isSingle && gallery.length > 1) {
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prevBtn = document.createElement("button");
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prevBtn.className = "lightbox-nav lightbox-prev";
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prevBtn.setAttribute("type", "button");
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prevBtn.setAttribute("aria-label", "上一张");
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prevBtn.textContent = "\u2039";
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nextBtn = document.createElement("button");
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nextBtn.className = "lightbox-nav lightbox-next";
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nextBtn.setAttribute("type", "button");
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nextBtn.setAttribute("aria-label", "下一张");
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nextBtn.textContent = "\u203a";
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}
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overlay.appendChild(img);
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overlay.appendChild(caption);
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overlay.appendChild(counter);
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if (prevBtn) overlay.appendChild(prevBtn);
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if (nextBtn) overlay.appendChild(nextBtn);
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document.body.appendChild(overlay);
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state = {
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overlay: overlay,
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img: img,
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caption: caption,
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counter: counter,
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prevBtn: prevBtn,
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nextBtn: nextBtn,
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originNode: originNode,
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gallery: gallery,
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index: index,
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isSingle: isSingle,
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openScrollY: window.scrollY,
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origSrc: origSrc,
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altText: altText,
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closing: false,
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reduced: prefersReducedMotion(),
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scrollHandler: null,
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keyHandler: null,
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};
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// 焦点移入灯箱
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overlay.focus();
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// 立即绑定交互（不等图片加载）：加载期间 Esc/滚动/点背景也须可关闭。
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bindInteractions();
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// 图片加载后再做动画（naturalW/H 要等加载）
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var start = function () {
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if (!state) return; // 加载前可能已被关闭
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var naturalW = img.naturalWidth || img.clientWidth || 1;
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var naturalH = img.naturalHeight || img.clientHeight || 1;
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var originRect = rectOf(originNode);
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// 基准 = originRect（文章里图片的实际尺寸）。
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// img 的布局尺寸固定为 originRect，transform 的 scale 相对它缩放：
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// 首帧（文章位置）scale=1，居中态 scale=target.w/originRect.w。
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// 这样无论 target 比 originRect 大或小，动画都是「从文章图原样连续缩放」，
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// 视觉上是原地展开，不会像「从外面飞来」。灯箱图尺寸恒为视口最大（fitCentered）。
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var target = fitCentered(naturalW, naturalH, vw, vh);
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var baseW = originRect.w;
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var baseH = originRect.h;
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// 存基准与目标，供关闭/滚动关闭复用同一对（保证 scale 连续）。
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state.target = target;
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state.baseW = baseW;
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state.baseH = baseH;
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img.style.width = baseW + "px";
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img.style.height = baseH + "px";
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// reduced-motion：直接淡入居中
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if (state.reduced) {
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img.style.opacity = "0";
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img.style.transform = transformFor(target, baseW, baseH);
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img.style.left = "0";
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img.style.top = "0";
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overlay.style.opacity = "0";
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// 下一帧淡入
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requestAnimationFrame(function () {
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if (!state) return;
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overlay.style.transition = "opacity 200ms ease-out";
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img.style.transition = "opacity 200ms ease-out";
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overlay.style.opacity = "1";
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img.style.opacity = "1";
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});
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return;
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}
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// 首帧：文章位置 + 原尺寸（scale=1），透明，且关闭 transition
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img.style.transition = "none";
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img.style.left = "0";
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img.style.top = "0";
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img.style.transform = transformFor(originRect, baseW, baseH);
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img.style.opacity = "0";
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overlay.style.opacity = "0";
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// 强制 reflow，确保首帧的 transform 已提交到渲染层。
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// 否则单层 rAF 里浏览器可能合并首帧与目标帧，动画从错误位置起跳。
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void img.offsetHeight;
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// double-rAF：第一帧绘制首帧（无动画），第二帧才启动 transition 到居中。
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requestAnimationFrame(function () {
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if (!state) return;
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requestAnimationFrame(function () {
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if (!state) return;
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img.style.transition =
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"transform 250ms ease-out, opacity 250ms ease-out";
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overlay.style.transition = "opacity 250ms ease-out";
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img.style.transform = transformFor(target, baseW, baseH);
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img.style.opacity = "1";
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overlay.style.opacity = "1";
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});
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});
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};
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if (img.complete && img.naturalWidth) {
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start();
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} else {
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img.addEventListener("load", start, { once: true });
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}
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img.src = origSrc;
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}
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function closeLightbox(immediate) {
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if (!state || state.closing) return;
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state.closing = true;
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cleanupInteractions();
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var s = state;
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// 基准 = originRect 尺寸（与打开时一致），scale 相对它缩放。
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var baseW = s.baseW || (s.target ? s.target.w : 1);
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var baseH = s.baseH || (s.target ? s.target.h : 1);
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var originRect = rectOf(s.originNode); // 实时读，处理期间滚动过的情况
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if (s.reduced || immediate) {
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removeOverlay();
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return;
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}
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// 飞回 originRect：scale 从 1 缩到 originRect.w/baseW
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s.img.style.transition =
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"transform 250ms ease-out, opacity 250ms ease-out";
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s.overlay.style.transition = "opacity 250ms ease-out";
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s.img.style.transform = transformFor(originRect, baseW, baseH);
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s.img.style.opacity = "0";
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s.overlay.style.opacity = "0";
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var done = function () {
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removeOverlay();
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};
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// 250ms 兜底，避免 transitionend 不触发
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var timer = setTimeout(done, 280);
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s.img.addEventListener("transitionend", function () { clearTimeout(timer); done(); }, { once: true });
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}
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function removeOverlay() {
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if (!state) return;
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var prev = state.originNode;
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if (state.overlay && state.overlay.parentNode) {
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state.overlay.parentNode.removeChild(state.overlay);
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}
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state = null;
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// 焦点归还：.blur-img 是 span 不可聚焦，让其内部 full img 获得焦点
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if (prev) {
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var f = prev.querySelector(".blur-img-full");
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if (f) {
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f.setAttribute("tabindex", "-1");
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f.focus();
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}
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}
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}
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// ============ 图集切换 ============
|
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// 图集切换：淡入淡出，不飞行。newIndex 循环（首尾衔接）。
|
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function gotoIndex(newIndex) {
|
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if (!state || state.isSingle) return;
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var s = state;
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if (!s.gallery || s.gallery.length === 0) return;
|
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if (newIndex < 0) newIndex = s.gallery.length - 1;
|
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if (newIndex >= s.gallery.length) newIndex = 0;
|
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if (newIndex === s.index) return;
|
||
|
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var newNode = s.gallery[newIndex];
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var fullImg = newNode.querySelector(".blur-img-full");
|
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if (!fullImg) return;
|
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var origSrc = originalUrl(fullImg.getAttribute("data-src") || "");
|
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var altText = fullImg.getAttribute("alt") || "";
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|
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// 淡出当前图
|
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s.img.style.transition = "opacity 150ms ease-out";
|
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s.img.style.opacity = "0";
|
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|
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// 150ms 后换图淡入
|
||
var swap = function () {
|
||
if (!state) return; // 切换中可能已关闭
|
||
var fade = function () {
|
||
if (!state) return;
|
||
s.img.style.transition = "opacity 150ms ease-out";
|
||
s.img.style.opacity = "1";
|
||
};
|
||
if (s.img.complete && s.img.naturalWidth) {
|
||
// 缓存命中，直接淡入
|
||
s.img.src = origSrc;
|
||
fade();
|
||
} else {
|
||
s.img.addEventListener("load", fade, { once: true });
|
||
s.img.src = origSrc;
|
||
}
|
||
s.caption.textContent = altText;
|
||
s.caption.style.display = altText ? "" : "none";
|
||
s.counter.textContent = newIndex + 1 + " / " + s.gallery.length;
|
||
// 更新 originNode 为新图，使后续关闭/滚动关闭飞回新图位置
|
||
s.originNode = newNode;
|
||
s.index = newIndex;
|
||
s.openScrollY = window.scrollY; // 重置滚动关闭基线
|
||
};
|
||
setTimeout(swap, 150);
|
||
}
|
||
|
||
// ============ 交互绑定 ============
|
||
|
||
function bindInteractions() {
|
||
var s = state;
|
||
if (!s) return;
|
||
|
||
// 点背景关闭（点图片本身不关，因箭头在图上、避免误关）
|
||
s.overlay.addEventListener("click", function (ev) {
|
||
if (state && ev.target === state.overlay) closeLightbox(false);
|
||
});
|
||
|
||
// 滚动驱动关闭：任何 scroll 都触发，用 scrollY 偏移算进度。
|
||
// 关键：逐帧读 originNode 实时 rect，文章滚多少图就回多少。
|
||
s.scrollHandler = function () {
|
||
if (!state) return;
|
||
var st = state;
|
||
if (st.closing) return;
|
||
var dy = Math.abs(window.scrollY - st.openScrollY);
|
||
if (st.reduced) {
|
||
// reduced-motion：立即关
|
||
closeLightbox(true);
|
||
return;
|
||
}
|
||
var progress = Math.min(dy / 120, 1);
|
||
var target = st.target;
|
||
var baseW = st.baseW || (target ? target.w : 1);
|
||
var baseH = st.baseH || (target ? target.h : 1);
|
||
var originRect = rectOf(st.originNode);
|
||
// 在 originRect 与居中 target 之间按 progress 线性插值
|
||
var cur = {
|
||
x: target.x + (originRect.x - target.x) * progress,
|
||
y: target.y + (originRect.y - target.y) * progress,
|
||
w: target.w + (originRect.w - target.w) * progress,
|
||
h: target.h + (originRect.h - target.h) * progress,
|
||
};
|
||
st.img.style.transition = "none";
|
||
st.img.style.transform = transformFor(cur, baseW, baseH);
|
||
st.img.style.opacity = String(1 - progress);
|
||
st.overlay.style.opacity = String(1 - progress);
|
||
if (progress >= 1) {
|
||
// 已飞回原位：文章停在当前滚动位置，移除灯箱
|
||
st.closing = true;
|
||
cleanupInteractions();
|
||
removeOverlay();
|
||
}
|
||
};
|
||
window.addEventListener("scroll", s.scrollHandler, { passive: true });
|
||
|
||
// 键盘：Esc 关；图集模式 ←→ 切换
|
||
s.keyHandler = function (ev) {
|
||
if (!state) return;
|
||
if (ev.key === "Escape") {
|
||
closeLightbox(false);
|
||
} else if (!state.isSingle && state.gallery.length > 1) {
|
||
if (ev.key === "ArrowLeft") {
|
||
ev.preventDefault();
|
||
gotoIndex(state.index - 1);
|
||
} else if (ev.key === "ArrowRight") {
|
||
ev.preventDefault();
|
||
gotoIndex(state.index + 1);
|
||
}
|
||
}
|
||
};
|
||
document.addEventListener("keydown", s.keyHandler);
|
||
|
||
// 图集导航箭头点击（stopPropagation 防止冒泡到 overlay 触发关闭）
|
||
if (s.prevBtn) {
|
||
s.prevBtn.addEventListener("click", function (ev) {
|
||
ev.stopPropagation();
|
||
if (state) gotoIndex(state.index - 1);
|
||
});
|
||
}
|
||
if (s.nextBtn) {
|
||
s.nextBtn.addEventListener("click", function (ev) {
|
||
ev.stopPropagation();
|
||
if (state) gotoIndex(state.index + 1);
|
||
});
|
||
}
|
||
}
|
||
|
||
function cleanupInteractions() {
|
||
if (!state) return;
|
||
if (state.scrollHandler) {
|
||
window.removeEventListener("scroll", state.scrollHandler);
|
||
state.scrollHandler = null;
|
||
}
|
||
if (state.keyHandler) {
|
||
document.removeEventListener("keydown", state.keyHandler);
|
||
state.keyHandler = null;
|
||
}
|
||
}
|
||
|
||
// ============ 初始化入口 ============
|
||
|
||
window.__initLightbox = function (selectors) {
|
||
// selectors 可以是字符串、字符串数组
|
||
var sels = Array.isArray(selectors) ? selectors : [selectors];
|
||
var roots = [];
|
||
for (var i = 0; i < sels.length; i++) {
|
||
var found = document.querySelectorAll(sels[i]);
|
||
for (var j = 0; j < found.length; j++) roots.push(found[j]);
|
||
}
|
||
|
||
// 先对所有图片做懒加载（图集与单张都做）
|
||
var collected = collectImages(roots);
|
||
var everyone = collected.gallery.concat(collected.singles);
|
||
for (var k = 0; k < everyone.length; k++) {
|
||
initLazyLoad(everyone[k]);
|
||
}
|
||
|
||
// 正文图：带 index
|
||
var gallery = collected.gallery;
|
||
for (var g = 0; g < gallery.length; g++) {
|
||
(function (node, idx) {
|
||
node.addEventListener("click", function (e) {
|
||
e.preventDefault();
|
||
openLightbox(node, gallery, idx);
|
||
});
|
||
})(gallery[g], g);
|
||
}
|
||
// 单张图（封面）：index = null，gallery 传空数组表示单张
|
||
for (var si = 0; si < collected.singles.length; si++) {
|
||
(function (node) {
|
||
node.addEventListener("click", function (e) {
|
||
e.preventDefault();
|
||
openLightbox(node, [], null);
|
||
});
|
||
})(collected.singles[si]);
|
||
}
|
||
};
|
||
})();
|