二维码扫描优化，但是开票页面必须在微信浏览器中打开。

该项目暂停。

tests/qrscan.test.js

@@ -1,8 +1,9 @@
-import { describe, it, expect } from "vitest";
+import { describe, it, expect } from "vitest";
 import QRCode from "qrcode";
 import {
   extractUrl,
   decodeQrFromImageData,
+  scaleImageData,
 } from "../src/qrscan.js";
 
 /**
@@ -18,11 +19,10 @@ function renderQrImageData(text, scale = 8, quiet = 4) {
   const modules = qr.modules.data;
   const dim = (size + quiet * 2) * scale;
   const data = new Uint8ClampedArray(dim * dim * 4);
-  // 先整体填白（含静区）。
   data.fill(255);
   for (let row = 0; row < size; row += 1) {
     for (let col = 0; col < size; col += 1) {
-      if (!modules[row * size + col]) continue; // 0 = 浅色，跳过
+      if (!modules[row * size + col]) continue;
       const x0 = (col + quiet) * scale;
       const y0 = (row + quiet) * scale;
       for (let dy = 0; dy < scale; dy += 1) {
@@ -39,6 +39,45 @@ function renderQrImageData(text, scale = 8, quiet = 4) {
   return { data, width: dim, height: dim };
 }
 
+/**
+ * 将小二维码嵌入大画布中央，模拟手机拍摄的远景照片（二维码占比小）。
+ * @param {string} text 二维码内容。
+ * @param {number} canvasW 大画布宽度。
+ * @param {number} canvasH 大画布高度。
+ * @returns {ImageData} 大画布像素数据。
+ */
+function embedSmallQr(text, canvasW = 600, canvasH = 400) {
+  const qr = QRCode.create(text, { errorCorrectionLevel: "M" });
+  const size = qr.modules.size;
+  const modules = qr.modules.data;
+  const scale = 3; // 每个模块 3px，二维码约 80px
+  const quiet = 1;
+  const qrW = (size + quiet * 2) * scale;
+  const qrH = qrW;
+  const ox = Math.floor((canvasW - qrW) / 2);
+  const oy = Math.floor((canvasH - qrH) / 2);
+
+  const data = new Uint8ClampedArray(canvasW * canvasH * 4);
+  data.fill(255);
+  for (let row = 0; row < size; row += 1) {
+    for (let col = 0; col < size; col += 1) {
+      if (!modules[row * size + col]) continue;
+      const x0 = ox + (col + quiet) * scale;
+      const y0 = oy + (row + quiet) * scale;
+      for (let dy = 0; dy < scale; dy += 1) {
+        for (let dx = 0; dx < scale; dx += 1) {
+          const idx = ((y0 + dy) * canvasW + (x0 + dx)) * 4;
+          data[idx] = 0;
+          data[idx + 1] = 0;
+          data[idx + 2] = 0;
+          data[idx + 3] = 255;
+        }
+      }
+    }
+  }
+  return { data, width: canvasW, height: canvasH };
+}
+
 describe("qrscan", () => {
   // 4-1 网址校验：接受 http/https，拒绝其它内容。
   it("4-1 extractUrl 仅接受 http/https 网址", () => {
@@ -68,4 +107,25 @@ describe("qrscan", () => {
     expect(decodeQrFromImageData(blank)).toBeNull();
     expect(decodeQrFromImageData(null)).toBeNull();
   });
+
+  // 4-4 多级缩放回退：大画布中小二维码，原始尺寸失败但缩小后成功。
+  it("4-4 多级缩放回退能识别大图中的小二维码", () => {
+    const url = "https://inv.example.com/small";
+    const imageData = embedSmallQr(url, 800, 600);
+    const result = decodeQrFromImageData(imageData);
+    expect(result).toBe(url);
+  });
+
+  // 4-5 scaleImageData 等比缩放正确。
+  it("4-5 scaleImageData 等比缩放", () => {
+    const src = renderQrImageData("test", 4);
+    const half = scaleImageData(src, 0.5);
+    expect(half.width).toBe(Math.floor(src.width * 0.5));
+    expect(half.height).toBe(Math.floor(src.height * 0.5));
+    expect(half.data).toBeInstanceOf(Uint8ClampedArray);
+    expect(half.data.length).toBe(half.width * half.height * 4);
+    expect(half.height).toBe(Math.floor(src.height * 0.5));
+  });
 });
+
+