fix: canvas image/video download - fix data URL parsing in cvDownloadPreview (v1.5.21, hot 1.5.23)

2026-07-20 08:48:56 +08:00
parent 42e23663ee
commit aadd2b04ae
28 changed files with 5881 additions and 329 deletions
@@ -47,4 +47,101 @@ function extractZip(buf, destDir) {
  return written;
 }

-module.exports = { extractZip };
+// ---- 零依赖 ZIP 压缩（deflate/stored），供员工团队打包等复用 ----
+// CRC32 表（懒加载）
+let CRC_TABLE = null;
+function crc32(buf) {
+  if (!CRC_TABLE) {
+    CRC_TABLE = new Int32Array(256);
+    for (let n = 0; n < 256; n++) {
+      let c = n;
+      for (let k = 0; k < 8; k++) c = c & 1 ? 0xedb88320 ^ (c >>> 1) : c >>> 1;
+      CRC_TABLE[n] = c;
+    }
+  }
+  let crc = ~0;
+  for (let i = 0; i < buf.length; i++) crc = (crc >>> 8) ^ CRC_TABLE[(crc ^ buf[i]) & 0xff];
+  return (~crc) >>> 0;
+}
+
+// MS-DOS 时间/日期（固定用一个合法值即可，不追求精确时间戳）
+function dosDateTime(d) {
+  const date = d || new Date();
+  const time = ((date.getHours() & 0x1f) << 11) | ((date.getMinutes() & 0x3f) << 5) | ((date.getSeconds() / 2) & 0x1f);
+  const day = (((date.getFullYear() - 1980) & 0x7f) << 9) | (((date.getMonth() + 1) & 0x0f) << 5) | (date.getDate() & 0x1f);
+  return { time: time & 0xffff, date: day & 0xffff };
+}
+
+// files: [{ path, content(string|Buffer), mode?(unix 权限，如 0o755) }]
+// 返回一个 zip 的 Buffer。目录靠文件路径里的 "/" 隐含，无需单独目录项。
+function createZip(files) {
+  const { time, date } = dosDateTime();
+  const locals = [];
+  const centrals = [];
+  let offset = 0;
+  for (const f of files) {
+    const nameBuf = Buffer.from(String(f.path).replace(/^\/+/, ""), "utf8");
+    const raw = Buffer.isBuffer(f.content) ? f.content : Buffer.from(String(f.content == null ? "" : f.content), "utf8");
+    const crc = crc32(raw);
+    // 尝试 deflate；若压不小就存储（method 0）
+    let method = 8;
+    let comp = zlib.deflateRawSync(raw, { level: 9 });
+    if (comp.length >= raw.length) { method = 0; comp = raw; }
+
+    // 本地文件头
+    const lh = Buffer.alloc(30);
+    lh.writeUInt32LE(0x04034b50, 0);
+    lh.writeUInt16LE(20, 4);            // version needed
+    lh.writeUInt16LE(0, 6);             // flags
+    lh.writeUInt16LE(method, 8);
+    lh.writeUInt16LE(time, 10);
+    lh.writeUInt16LE(date, 12);
+    lh.writeUInt32LE(crc, 14);
+    lh.writeUInt32LE(comp.length, 18);
+    lh.writeUInt32LE(raw.length, 22);
+    lh.writeUInt16LE(nameBuf.length, 26);
+    lh.writeUInt16LE(0, 28);           // extra len
+    locals.push(lh, nameBuf, comp);
+
+    // 中央目录项
+    const ch = Buffer.alloc(46);
+    // unix 权限写进外部属性高 16 位（低位保留），默认 0644，可执行给 0755
+    const unixMode = f.mode ? f.mode : 0o644;
+    const externalAttr = (unixMode << 16) >>> 0;
+    ch.writeUInt32LE(0x02014b50, 0);
+    ch.writeUInt16LE(0x031e, 4);       // version made by (unix)
+    ch.writeUInt16LE(20, 6);           // version needed
+    ch.writeUInt16LE(0, 8);            // flags
+    ch.writeUInt16LE(method, 10);
+    ch.writeUInt16LE(time, 12);
+    ch.writeUInt16LE(date, 14);
+    ch.writeUInt32LE(crc, 16);
+    ch.writeUInt32LE(comp.length, 20);
+    ch.writeUInt32LE(raw.length, 24);
+    ch.writeUInt16LE(nameBuf.length, 28);
+    ch.writeUInt16LE(0, 30);           // extra len
+    ch.writeUInt16LE(0, 32);           // comment len
+    ch.writeUInt16LE(0, 34);           // disk number
+    ch.writeUInt16LE(0, 36);           // internal attr
+    ch.writeUInt32LE(externalAttr, 38);
+    ch.writeUInt32LE(offset, 42);
+    centrals.push(ch, nameBuf);
+
+    offset += lh.length + nameBuf.length + comp.length;
+  }
+
+  const localPart = Buffer.concat(locals);
+  const centralPart = Buffer.concat(centrals);
+  const eocd = Buffer.alloc(22);
+  eocd.writeUInt32LE(0x06054b50, 0);
+  eocd.writeUInt16LE(0, 4);
+  eocd.writeUInt16LE(0, 6);
+  eocd.writeUInt16LE(files.length, 8);
+  eocd.writeUInt16LE(files.length, 10);
+  eocd.writeUInt32LE(centralPart.length, 12);
+  eocd.writeUInt32LE(localPart.length, 16); // central dir offset
+  eocd.writeUInt16LE(0, 20);
+  return Buffer.concat([localPart, centralPart, eocd]);
+}
+
+module.exports = { extractZip, createZip };