Google-Drive-PDF-Downloader

How It Works

• Google Drive Preview often displays PDF pages as separate images (blob URLs).
• This script gathers those images from your browser (which you already have permission to view).
• jsPDF combines these images into a single PDF file, which you can download.

Note: This script does not bypass Google Drive permissions. You must have valid access and must load (view) all pages in the preview.

Usage

1. Open the Google Drive PDF link in your browser.
2. Scroll through the entire PDF preview, ensuring each page is fully loaded (you should see each page in the preview). This is crucial because the script can only capture images that are already loaded in your browser.
3. Open Developer Tools (typically F12 or Ctrl + Shift + I).
4. Switch to the Console tab in Developer Tools.
5. Copy the script below and paste it into the console.
6. Press Enter to run the script.
7. Wait for the script to finish. Status messages (number of images found, generation progress, etc.) will appear in the console.
8. Automatic Download of the new PDF should begin once finished.

Script

(function () {
  console.log("Loading script...");

  // Helper function: Loads the jsPDF library and returns a promise when it's ready.
  function loadJSPDF(url) {
    return new Promise((resolve, reject) => {
      const script = document.createElement("script");

      // If Trusted Types is supported, create a policy for our script URL.
      if (window.trustedTypes && trustedTypes.createPolicy) {
        const policy = trustedTypes.createPolicy("myPolicy", {
          createScriptURL: (input) => input,
        });
        script.src = policy.createScriptURL(url);
      } else {
        script.src = url;
      }

      script.onload = () => {
        console.log("jsPDF library loaded successfully.");
        resolve();
      };
      script.onerror = () => reject(new Error("Failed to load jsPDF."));

      document.body.appendChild(script);
    });
  }

  // Helper function: Detect images in the DOM that start with the "blob:https://drive.google.com/" prefix.
  function getValidImages() {
    const images = document.getElementsByTagName("img");
    const validImgs = [];
    const driveBlobPrefix = "blob:https://drive.google.com/";

    for (let i = 0; i < images.length; i++) {
      const img = images[i];
      if (img.src.startsWith(driveBlobPrefix)) {
        validImgs.push(img);
      }
    }
    return validImgs;
  }

  // Helper function: Convert an <img> element to a base64 data URL using a canvas.
  function convertImageToDataUrl(imgElement) {
    const canvas = document.createElement("canvas");
    const ctx = canvas.getContext("2d");

    canvas.width = imgElement.naturalWidth;
    canvas.height = imgElement.naturalHeight;

    ctx.drawImage(imgElement, 0, 0, imgElement.naturalWidth, imgElement.naturalHeight);
    return canvas.toDataURL();
  }

  // Main function: Generates and downloads a PDF from the valid images found on the page.
  function generatePDFFromImages(images) {
    if (!images || !images.length) {
      console.warn("No images found that match the Drive blob criteria.");
      return;
    }

    // We'll access jsPDF through the UMD global object: `window.jspdf.jsPDF`.
    const { jsPDF } = window.jspdf;

    console.log(`${images.length} valid image(s) found. Building PDF...`);

    let pdf;
    let isFirstPage = true;

    images.forEach((img, idx) => {
      const imgData = convertImageToDataUrl(img);

      const orientation = img.naturalWidth > img.naturalHeight ? "l" : "p";
      const pageWidth = img.naturalWidth;
      const pageHeight = img.naturalHeight;

      // Initialize PDF on the first valid image.
      if (isFirstPage) {
        pdf = new jsPDF({
          orientation: orientation,
          unit: "px",
          format: [pageWidth, pageHeight],
        });
        isFirstPage = false;
      } else {
        pdf.addPage([pageWidth, pageHeight], orientation);
      }

      pdf.addImage(imgData, "PNG", 0, 0, pageWidth, pageHeight);

      const percentDone = Math.round(((idx + 1) / images.length) * 100);
      console.log(`Processing image ${idx + 1}/${images.length} (${percentDone}%)`);
    });

    // Extract a title from the page's meta if available, otherwise use "download.pdf".
    let title = "download.pdf";
    const metaTitle = document.querySelector('meta[itemprop="name"]');
    if (metaTitle && metaTitle.content) {
      title = metaTitle.content.endsWith(".pdf") ? metaTitle.content : `${metaTitle.content}.pdf`;
    }

    console.log("Saving PDF...");
    pdf.save(title, { returnPromise: true }).then(() => {
      console.log("PDF downloaded successfully!");
    });
  }

  // 1) Load jsPDF
  // 2) Gather valid images
  // 3) Generate & download PDF
  loadJSPDF("https://unpkg.com/jspdf@latest/dist/jspdf.umd.min.js")
    .then(() => {
      const images = getValidImages();
      generatePDFFromImages(images);
    })
    .catch((err) => console.error(err));
})();