完善生图5.0的功能

lib/client/zip-download.ts

@@ -0,0 +1,121 @@
+type DownloadableFile = {
+  name: string;
+  url: string;
+};
+
+type ZipEntry = {
+  name: Uint8Array;
+  data: Uint8Array;
+  crc: number;
+  offset: number;
+};
+
+export async function downloadFilesAsZip(files: DownloadableFile[], archiveName: string) {
+  if (!files.length) return;
+  const usedNames = new Set<string>();
+  const entries: ZipEntry[] = [];
+  for (let index = 0; index < files.length; index += 1) {
+    const file = files[index];
+    const response = await fetch(file.url, { credentials: "same-origin" });
+    if (!response.ok) throw new Error(`下载第 ${index + 1} 个图层失败`);
+    const data = new Uint8Array(await response.arrayBuffer());
+    const safeName = uniqueFileName(sanitizeFileName(file.name) || `layer-${index}.png`, usedNames);
+    entries.push({ name: new TextEncoder().encode(safeName), data, crc: crc32(data), offset: 0 });
+  }
+  const blob = zipBlob(entries);
+  const href = URL.createObjectURL(blob);
+  const anchor = document.createElement("a");
+  anchor.href = href;
+  anchor.download = sanitizeFileName(archiveName) || "seedream-layers.zip";
+  document.body.appendChild(anchor);
+  anchor.click();
+  anchor.remove();
+  window.setTimeout(() => URL.revokeObjectURL(href), 1000);
+}
+
+function zipBlob(entries: ZipEntry[]) {
+  const localParts: Uint8Array[] = [];
+  let offset = 0;
+  for (const entry of entries) {
+    entry.offset = offset;
+    const header = new Uint8Array(30 + entry.name.length);
+    const view = new DataView(header.buffer);
+    view.setUint32(0, 0x04034b50, true);
+    view.setUint16(4, 20, true);
+    view.setUint16(6, 0x0800, true);
+    view.setUint16(8, 0, true);
+    view.setUint32(14, entry.crc, true);
+    view.setUint32(18, entry.data.length, true);
+    view.setUint32(22, entry.data.length, true);
+    view.setUint16(26, entry.name.length, true);
+    header.set(entry.name, 30);
+    localParts.push(header, entry.data);
+    offset += header.length + entry.data.length;
+  }
+
+  const centralOffset = offset;
+  const centralParts: Uint8Array[] = [];
+  for (const entry of entries) {
+    const header = new Uint8Array(46 + entry.name.length);
+    const view = new DataView(header.buffer);
+    view.setUint32(0, 0x02014b50, true);
+    view.setUint16(4, 20, true);
+    view.setUint16(6, 20, true);
+    view.setUint16(8, 0x0800, true);
+    view.setUint16(10, 0, true);
+    view.setUint32(16, entry.crc, true);
+    view.setUint32(20, entry.data.length, true);
+    view.setUint32(24, entry.data.length, true);
+    view.setUint16(28, entry.name.length, true);
+    view.setUint32(42, entry.offset, true);
+    header.set(entry.name, 46);
+    centralParts.push(header);
+    offset += header.length;
+  }
+
+  const end = new Uint8Array(22);
+  const endView = new DataView(end.buffer);
+  endView.setUint32(0, 0x06054b50, true);
+  endView.setUint16(8, entries.length, true);
+  endView.setUint16(10, entries.length, true);
+  endView.setUint32(12, offset - centralOffset, true);
+  endView.setUint32(16, centralOffset, true);
+  return new Blob([...localParts, ...centralParts, end].map(arrayBufferCopy), { type: "application/zip" });
+}
+
+function arrayBufferCopy(value: Uint8Array) {
+  const copy = new Uint8Array(value.byteLength);
+  copy.set(value);
+  return copy.buffer;
+}
+
+function sanitizeFileName(value: string) {
+  return value.trim().replace(/[\\/:*?"<>|\u0000-\u001f]/g, "-").replace(/^\.+/, "").slice(0, 120);
+}
+
+function uniqueFileName(name: string, used: Set<string>) {
+  if (!used.has(name)) {
+    used.add(name);
+    return name;
+  }
+  const dot = name.lastIndexOf(".");
+  const base = dot > 0 ? name.slice(0, dot) : name;
+  const extension = dot > 0 ? name.slice(dot) : "";
+  let index = 2;
+  while (used.has(`${base}-${index}${extension}`)) index += 1;
+  const result = `${base}-${index}${extension}`;
+  used.add(result);
+  return result;
+}
+
+const crcTable = Array.from({ length: 256 }, (_, index) => {
+  let value = index;
+  for (let bit = 0; bit < 8; bit += 1) value = (value & 1) ? 0xedb88320 ^ (value >>> 1) : value >>> 1;
+  return value >>> 0;
+});
+
+function crc32(data: Uint8Array) {
+  let crc = 0xffffffff;
+  for (const value of data) crc = crcTable[(crc ^ value) & 0xff] ^ (crc >>> 8);
+  return (crc ^ 0xffffffff) >>> 0;
+}