Getting the width and height of an image attachment

Question

Is it possible to get the width and height of an image in an Attachment?

I'm looking for a way to make it show properly based on the image.

<apex:image value="https://c.ap1.content.force.com/servlet/servlet.FileDownload?file={!a.Id}" width="XXX" height="XXX"/>

Answer 1

I just tried following code and its alerting the width and height correctly. One approach would be to load images like this and add them to the dom as required

<apex:page>

  <script type="text/javascript">
    var img = new Image();
    img.onload = function() {
      // you can append this img tag in desired DOM location now with height/width as required.
      alert(this.width + 'x' + this.height);
    }
    img.src = 'https://c.ap1.content.force.com/sfc/servlet.shepherd/version/download/06890000000MkxY';

  </script>
</apex:page>

Another approach might be to do like this

<apex:page>

<script src="//ajax.googleapis.com/ajax/libs/jquery/1.8.0/jquery.min.js"></script>
<apex:image id="testImg" value="/s.gif" />
  <script type="text/javascript">
    $(document).ready(function () {
        $('img[id$=testImg]')             
            .attr('src', 'https://c.ap1.content.force.com/sfc/servlet.shepherd/version/download/06890000000MkxY')
            .load(function(){        
            // do what you want with height width here
                alert($(this).height() + ' X ' + $(this).width());

            });
    });
  </script>
</apex:page>

Hope this helps