Function convertJpegToPng

apps/OpenSign/src/constant/Utils.js:4774–4825

(base64Image, filename)

 * @returns {Promise<File>}     - A promise that resolves with a new PNG File.
 */
export function convertJpegToPng(base64Image, filename) {
  if (base64Image) {
    const arr = base64Image.split(",");
    const mimeMatch = arr[0].match(/:(.*?);/);
    if (!mimeMatch) throw new Error("Invalid dataURL");
    const mime = mimeMatch[1];
    const type = mime.split("/")[1];
    if (type === "png") {
      return base64Image;
    } else {
      const bstr = atob(arr[1]);
      let n = bstr.length;
      const u8arr = new Uint8Array(n);
      while (n--) u8arr[n] = bstr.charCodeAt(n);
      const inputFile = new File([u8arr], `${filename}.${type}`, {
        type: mime
      });
      return new Promise((resolve, reject) => {
        // ensure it’s JPEG/JPG (you can remove this check if not needed)
        if (!/image\/jpe?g/.test(inputFile.type)) {
          return reject(new Error("Input must be a JPEG or JPG image"));
        }

        // Read the file as a data URL
        const reader = new FileReader();
        reader.onerror = () => reject(new Error("Failed to read the file"));
        reader.onload = () => {
          const img = new Image();
          img.onerror = () => reject(new Error("Failed to load image"));
          img.onload = () => {
            // draw image onto a canvas
            const canvas = document.createElement("canvas");
            canvas.width = img.width;
            canvas.height = img.height;
            const ctx = canvas.getContext("2d");
            ctx.drawImage(img, 0, 0);

            // directly get PNG as base64 data URL
            try {
              const pngDataUrl = canvas.toDataURL("image/png");
              resolve(pngDataUrl);
            } catch (err) {
              reject(new Error("Failed to convert canvas to PNG"));
            }
          };
          img.src = reader.result;
        };
        reader.readAsDataURL(inputFile);
      });
    }
  }
}
//function is used to get assigned signer's email
export const getSignerEmail = (data, signers) => {
  const getEmail =