Initial commit

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

app/static/common/imgDecypt.js

@@ -0,0 +1,228 @@
+function imgEncrypt(buffer) {
+  var bytes = new Uint8Array(buffer);
+  var encoder = new TextEncoder();
+  var KEY = encoder.encode('2019ysapp7527');
+  for (var i = 0; i < Math.min(100, bytes.length); i++) {
+    bytes[i] ^= KEY[i % KEY.length];
+  }
+  var mime = 'image/jpeg';
+  if (bytes[0] === 0x47 && bytes[1] === 0x49 && bytes[2] === 0x46 && bytes[3] === 0x38) {
+    mime = 'image/gif';
+  } else if (bytes[0] === 0x89 && bytes[1] === 0x50 && bytes[2] === 0x4e && bytes[3] === 0x47) {
+    mime = 'image/png';
+  } else if (
+    bytes[0] === 0x52 && bytes[1] === 0x49 && bytes[2] === 0x46 && bytes[3] === 0x46 &&
+    bytes[8] === 0x57 && bytes[9] === 0x45 && bytes[10] === 0x42 && bytes[11] === 0x50
+  ) {
+    mime = 'image/webp';
+  }
+  var blob = new Blob([bytes], {
+    type: mime,
+  });
+  return URL.createObjectURL(blob);
+}
+
+var IMG_PLACEHOLDER = '/static/images/placeholder.png?v=2';
+var lazyImageObserver = null;
+var decryptedURLCache = Object.create(null);
+var decryptInflight = Object.create(null);
+var decryptQueue = [];
+var decryptActive = 0;
+// H5 弱网降低并发，优先完成 LCP 主图；PC 保持 4
+var DECRYPT_CONCURRENCY =
+  window.matchMedia && window.matchMedia("(max-width: 767px)").matches ? 2 : 4;
+
+function shouldDecryptImage(url) {
+  if (!url) return false;
+  var u = String(url).trim();
+  if (!u) return false;
+  if (u.indexOf('data:') === 0 || u.indexOf('blob:') === 0) return false;
+  if (u.indexOf('/static/') === 0) return false;
+  if (u.indexOf('placehold.co') >= 0) return false;
+  return true;
+}
+
+function applyImageResult(dom, type, url) {
+  if (!dom || !url) return;
+  if (type === 'bgImg') {
+    dom.style.setProperty('background-image', 'url("' + url + '")');
+  } else {
+    dom.src = url;
+  }
+}
+
+function fetchDecrypt(url, priority) {
+  if (decryptedURLCache[url]) {
+    return Promise.resolve(decryptedURLCache[url]);
+  }
+  if (decryptInflight[url]) {
+    return decryptInflight[url];
+  }
+
+  decryptInflight[url] = new Promise(function (resolve, reject) {
+    var run = function () {
+      decryptActive += 1;
+      var xhr = new XMLHttpRequest();
+      xhr.open('GET', url, true);
+      xhr.responseType = 'arraybuffer';
+      xhr.onload = function () {
+        decryptActive -= 1;
+        pumpDecryptQueue();
+        if (xhr.status === 200) {
+          var blobUrl = imgEncrypt(xhr.response);
+          decryptedURLCache[url] = blobUrl;
+          resolve(blobUrl);
+          return;
+        }
+        reject(xhr.status);
+      };
+      xhr.onerror = function () {
+        decryptActive -= 1;
+        pumpDecryptQueue();
+        reject('network');
+      };
+      xhr.send();
+    };
+
+    if (decryptActive < DECRYPT_CONCURRENCY) {
+      run();
+    } else if (priority) {
+      decryptQueue.unshift(run);
+    } else {
+      decryptQueue.push(run);
+    }
+  });
+  decryptInflight[url].then(
+    function () { delete decryptInflight[url]; },
+    function () { delete decryptInflight[url]; }
+  );
+
+  return decryptInflight[url];
+}
+
+function pumpDecryptQueue() {
+  while (decryptActive < DECRYPT_CONCURRENCY && decryptQueue.length) {
+    var next = decryptQueue.shift();
+    if (typeof next === 'function') next();
+  }
+}
+
+function processImage(url, dom, type, fallback) {
+  if (!url || !dom) {
+    return Promise.resolve('');
+  }
+
+  if (!shouldDecryptImage(url)) {
+    applyImageResult(dom, type, url);
+    return Promise.resolve(url);
+  }
+
+  var priority =
+    !!dom &&
+    (dom.getAttribute('fetchpriority') === 'high' ||
+      dom.getAttribute('data-lazy-eager') === '1');
+
+  return fetchDecrypt(url, priority)
+    .then(function (blobUrl) {
+      applyImageResult(dom, type, blobUrl);
+      return blobUrl;
+    })
+    .catch(function () {
+      if (dom.tagName === 'IMG') {
+        dom.src = fallback || IMG_PLACEHOLDER;
+      }
+      return '';
+    });
+}
+
+function loadLazyNode(node) {
+  if (!node || node.getAttribute('data-decrypted') === '1') {
+    return;
+  }
+  var src = node.getAttribute('data-src');
+  if (!src) {
+    return;
+  }
+  node.setAttribute('data-decrypted', '1');
+  if (node.tagName === 'IMG') {
+    if (!node.getAttribute('src')) {
+      node.src = IMG_PLACEHOLDER;
+    }
+    processImage(src, node);
+    return;
+  }
+  if (node.classList && node.classList.contains('blog-background')) {
+    processImage(src, node, 'bgImg');
+  }
+}
+
+function getLazyImageObserver() {
+  if (lazyImageObserver) {
+    return lazyImageObserver;
+  }
+  if (!('IntersectionObserver' in window)) {
+    return null;
+  }
+  lazyImageObserver = new IntersectionObserver(
+    function (entries) {
+      entries.forEach(function (entry) {
+        if (!entry.isIntersecting) {
+          return;
+        }
+        var node = entry.target;
+        lazyImageObserver.unobserve(node);
+        loadLazyNode(node);
+      });
+    },
+    {
+      rootMargin: '180px 0px',
+      threshold: 0.01,
+    }
+  );
+  return lazyImageObserver;
+}
+
+function observeLazyNode(node, eager) {
+  if (!node || node.getAttribute('data-decrypted') === '1') {
+    return;
+  }
+  if (
+    eager ||
+    node.getAttribute('fetchpriority') === 'high' ||
+    node.getAttribute('data-lazy-eager') === '1'
+  ) {
+    loadLazyNode(node);
+    return;
+  }
+  var observer = getLazyImageObserver();
+  if (!observer) {
+    loadLazyNode(node);
+    return;
+  }
+  observer.observe(node);
+}
+
+function initLazyImages(root, options) {
+  root = root || document;
+  options = options || {};
+  var eager = !!options.eager;
+
+  root.querySelectorAll('img.lazy[data-src]:not([data-decrypted])').forEach(function (img) {
+    observeLazyNode(img, eager);
+  });
+
+  root.querySelectorAll('.blog-background.lazy[data-src]:not([data-decrypted])').forEach(function (node) {
+    observeLazyNode(node, eager);
+  });
+}
+
+document.addEventListener('DOMContentLoaded', function () {
+  initLazyImages();
+});
+
+window.initLazyImages = initLazyImages;
+window.__lazyLoadImages = initLazyImages;
+window.loadLazyNode = loadLazyNode;
+window.processImage = processImage;
+window.imgEncrypt = imgEncrypt;
+window.shouldDecryptImage = shouldDecryptImage;