寻求可在网页展示PDF并禁止文本复制的JS插件（PDFObject无效）

Alright, let's break down your problem: you need a JavaScript-based way to show PDFs on a web page, with the critical requirement that users can't copy text from the PDF. The allowcopy parameter you tried with PDFObject doesn't work because it's not actually part of the Acrobat document open parameters—those only control view settings like zoom or bookmarks, not content permissions.

Here are the most reliable approaches I've used for this exact use case:

1. Render PDF as Images with pdf.js (Most Effective) #

The foolproof way to block text copying is to convert the PDF into images (using canvas) so there's no selectable text at all. Mozilla's open-source pdf.js library makes this straightforward—it renders each PDF page onto a canvas element, which displays as a static image.

Here's a quick implementation example:

<div id="pdf-container" style="height: 500px; overflow-y: auto;"></div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/pdf.js/3.11.174/pdf.min.js"></script>
<script>
  // Set up the worker script path (required for pdf.js)
  pdfjsLib.GlobalWorkerOptions.workerSrc = 'https://cdnjs.cloudflare.com/ajax/libs/pdf.js/3.11.174/pdf.worker.min.js';

  async function renderPDFAsImages() {
    try {
      // Load the PDF document
      const pdfDoc = await pdfjsLib.getDocument('sample-3pp.pdf').promise;
      const container = document.getElementById('pdf-container');

      // Render each page to a canvas
      for (let pageNum = 1; pageNum <= pdfDoc.numPages; pageNum++) {
        const page = await pdfDoc.getPage(pageNum);
        // Adjust scale to control image quality/size
        const viewport = page.getViewport({ scale: 1.2 });
        
        const canvas = document.createElement('canvas');
        const ctx = canvas.getContext('2d');
        canvas.height = viewport.height;
        canvas.width = viewport.width;

        // Render the page content to the canvas
        await page.render({
          canvasContext: ctx,
          viewport: viewport
        }).promise;

        // Add the canvas to the container
        container.appendChild(canvas);
        // Optional: Add spacing between pages
        const spacer = document.createElement('div');
        spacer.style.height = '10px';
        container.appendChild(spacer);
      }
    } catch (error) {
      console.error('Error rendering PDF:', error);
    }
  }

  // Initialize rendering
  renderPDFAsImages();
</script>

Pros: 100% blocks text copying (users can only screenshot, which is harder to convert to editable text).
Cons: Loses native PDF features like search, bookmark navigation, and text selection for legitimate use cases. Also, large PDFs may load slower.

2. Encrypt the PDF File First (Prevent Copy at Source) #

Before embedding the PDF, use a tool like Adobe Acrobat or open-source alternatives to encrypt the PDF and disable the "Allow text copying" permission. When you embed this encrypted PDF via PDFObject or a simple <embed> tag, most browser PDF readers will respect these permissions natively.

This way, you can keep the native PDF interaction (zoom, scroll, bookmarks) while blocking copying. The downside is that determined users can still find workarounds (like using PDF cracking tools), but it's effective for most casual users.

3. Transparent Overlay Hack (Quick, But Not Foolproof) #

If you want to stick with native PDF embedding and just need a quick fix for non-technical users, add a transparent, click-through overlay over the PDF container. This prevents users from selecting text with their mouse, but tech-savvy users can remove the overlay via browser dev tools.

Example code:

<!-- Wrap PDF in a relative container -->
<div style="position: relative; height: 500px;">
  <div id="pdf" style="height: 100%;"></div>
  <!-- Transparent overlay that blocks text selection -->
  <div style="
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none; <!-- Let clicks/scroll pass through to PDF -->
    user-select: none; <!-- Prevent accidental selection -->
  "></div>
</div>
<script>
  const options = { height: "100%" };
  PDFObject.embed("sample-3pp.pdf", document.getElementById("pdf"), options);
</script>

Pros: Easy to implement, preserves all native PDF features.
Cons: Not secure against technical users.

Why Your Original PDFObject Approach Failed #

As you noticed, allowcopy isn't a valid parameter in the Acrobat SDK's document open parameters. Those parameters only control how the PDF is displayed (e.g., view: 'FitBV' sets initial zoom, pagemode shows bookmarks), not content permissions. The only way to enforce copy restrictions is either at the PDF file level (encryption) or by rendering the content in a non-selectable format (like images).

内容的提问来源于stack exchange，提问作者user13647429