3D FlipBook - Thumbnail not renewed when PDF changes


My users need to see my PDF displayed in 3D Flipbook format before they can recommend changes. So I end up switching out PDFs for the same Flipbook fairly often. I love being able to do this so easily - once I've changed the PDF in the Media Library, I just go in the 3D Flipbook and reset the PDF setting. My only problem is that I'm using auto-thumbnails, and I often find that the thumbnail for that Flipbook has not changed. I found the auto-thumbnails file in ...wp-content/uploads/3dflipbook/auto-thumbnails, and found that deleting the thumbnail for that flipbook solved the problem; the correct thumbnail was then created.

Would you be able to change your code, so that changing the entry for PDF in the back-end for a 3D Flipbook would delete that thumbnail? That would make my life easier!

Thanks so much for this wonderful tool!



Just checked on our debug server: replace pdf file-> update the book-> refresh a page with thumbnail - works fine. Maybe browser cache problem? the code for this is:

  function post_auto_thumbnail_save($id, $b64) {
    $dir = get_auto_thumbnail_dir();
    $fn = $dir.'/'.$id.'.png';
    if($b64!=='') {
      if(!file_exists($dir)) {
        mkdir($dir, 0777, TRUE);
      file_put_contents($fn, base64_decode($b64));
    else if(file_exists($fn)){

it always overwrites.


I just ran into this issue too. The problem is that the above $id is based on the post/page ID, which does not change. So every time the PDF is changed, the thumbnail file does not change. For example, it stays as 120000.png. I just had to put special case rules for expiration in the apache config, but ideally the plugin should use a random filename when generating the thumbnail. Since the same filename is used, browsers may not see that the file changed and will use the cache expiration of the old thumbnail.

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