process_sheet/vue/src/utils/qrImage.ts

import qrcode from "./qrcode-generator";

const cache = new Map<string, string>();

type QrFactory = (
  typeNumber: number,
  errorCorrectionLevel: string
) => {
  addData: (data: string, mode?: string) => void;
  make: () => void;
  getModuleCount: () => number;
  isDark: (row: number, col: number) => boolean;
};

const createQr = qrcode as unknown as QrFactory;

/**
 * Integer-module PNG for Lodop ADD_PRINT_IMAGE.
 * Avoids Lodop QRCode raster blur and canvas anti-aliasing.
 */
export async function qrPngDataUrl(text: string, px = 640): Promise<string> {
  const key = `${px}|${text}`;
  const hit = cache.get(key);
  if (hit) {
    return hit;
  }
  const qr = createQr(0, "L");
  qr.addData(text, "Byte");
  qr.make();
  const count = qr.getModuleCount();
  const margin = 2;
  const n = count + margin * 2;
  const cell = Math.max(8, Math.floor(px / n));
  const size = cell * n;
  const canvas = document.createElement("canvas");
  canvas.width = size;
  canvas.height = size;
  const ctx = canvas.getContext("2d");
  if (!ctx) {
    throw new Error("无法生成二维码画布");
  }
  ctx.imageSmoothingEnabled = false;
  ctx.fillStyle = "#ffffff";
  ctx.fillRect(0, 0, size, size);
  ctx.fillStyle = "#000000";
  for (let row = 0; row < count; row++) {
    for (let col = 0; col < count; col++) {
      if (qr.isDark(row, col)) {
        ctx.fillRect((col + margin) * cell, (row + margin) * cell, cell, cell);
      }
    }
  }
  const url = canvas.toDataURL("image/png");
  cache.set(key, url);
  return url;
}