title: Facebook and Whatsapp sharing buttons
body: <p>I have an PHP page showing an image to the user, and I want them to share via Facebook or WhatsApp, 
  Here the code for the head part:</p>
  
  <pre><code>&lt;meta name="description" content="&lt;?php echo $Rowdati['metadescrizione'];?&gt;"&gt;
  &lt;meta name="keywords" content="&lt;?php echo $Rowdati['keywordsapp'];?&gt;"&gt;
  &lt;meta property="og:image" content="&lt;?php echo $urlimmagineuser; ?&gt;"&gt;
  &lt;meta property="og:image:type" content="image/png"&gt;
  &lt;meta property="og:image:width" content="400"&gt;
  &lt;meta property="og:image:height" content="400"&gt;
  &lt;meta property="og:title" content="&lt;?php echo $Rowdati['titolo_fb_share'];?&gt;"&gt;
  &lt;meta property="og:description " content="&lt;?php echo $Rowdati['descr_fb_share'];?&gt;"&gt;
  </code></pre>
  
  <p>Here the code for getting the image to share and display on the web page:</p>
  
  <pre><code>&lt;?php echo "&lt;a href='". $url ."' download='image-ready'&gt;
      &lt;img id='immaginelaborata' class='img-responsive' src='". $url ."' /&gt;
      &lt;/a&gt;";
  ?&gt;
  </code></pre>
  
  <p>Here the share buttons:</p>
  
  <pre><code>&lt;div class="col-sm-4" data-href="&lt;?php echo $actual_link;?&gt;" data-layout="button" data-size="large" data-mobile-iframe="true"&gt;
      &lt;button class="btn col-xs-12 scroll_effect shadow-top-down"&gt;
          &lt;a class="fb-xfbml-parse-ignore" target="_blank" href="https://www.facebook.com/sharer/sharer.php?u=&lt;?php echo $actual_link;?&gt;;src=sdkpreparse"&gt;
          &lt;i class="fa fa-facebook-square" aria-hidden="true"&gt;&lt;/i&gt;&lt;br&gt;share on FB&lt;/a&gt;
      &lt;/button&gt;
  &lt;/div&gt;
  &lt;div class="col-sm-4"&gt;
      &lt;button class="btn col-xs-12 scroll_effect shadow-top-down"&gt;
          &lt;?php 
              $actual_link = (isset($_SERVER['HTTPS']) ? "https" : "http") .         
              "://$_SERVER[HTTP_HOST]$_SERVER[REQUEST_URI]";
          ?&gt;
          &lt;a href="whatsapp://send?text=&lt;?php echo $Rowdati['testo_whatsapp'] . "http://mydomain.it";?&gt;" data-action="share/whatsapp/share"&gt;
              &lt;i class="fa fa-whatsapp" aria-hidden="true" &gt;&lt;/i&gt;&lt;br&gt;share on Whatsapp&lt;br&gt;
          &lt;/a&gt;
      &lt;/button&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>The page works fine, except that when i share it on Facebook or WhatsApp it does not return the image preview... 
  I cannot figure out why after checking and rechecking the code.</p>