Monday, December 3, 2007

Implementing a photo gallery viewlet for CompositePack using jQuery

CompositePack is a beautiful piece of code written by Godefroid Chapelle. We use CompositePack at La Jornada to create the frontpage for the breaking news edition.

Some time ago I was asked to create a viewlet for a photo gallery and we started testing some gallery products to accomplish this task. We tried FriendlyAlbum, Plone SmoothGallery, plonegalleryview and, the best and most promising by far, Slideshow Folder.

All products had limitations that keep me away from using them as a base for my solution. I didn't wanted to create any new content type neither, so the approach I followed was this:

  • use a folder as a container for the gallery; the name and description of the folder was going to be the title and introduction text for the gallery
  • use Image as the content type for the photos; the name and description of every image was going to be the alternative text (the alt attribute) and caption of the photo

Having this in mind, I started analyzing how to integrate one of the many JavaScript libraries available to create the gallery. I wanted to use KSS, as this framework is on the way to become the standard on the Plone world, but I abandoned the idea soon. KSS is still on development and most of the current work is being done on the Plone 3.0 branch. The only thing I found for Plone 2.5 was a product named PloneAzax with a 1.0 release in Alpha state. PloneAzax was more like a demo of how AJAX would be used in Plone 3.0, than an usable product. Worst: it had some conflicts with CompositePack and I didn't wanted to mess with it.

After some research on the web I decided to use jQuery JavaScript Library. jQuery is fast and concise, and it lets you traverse HTML documents and handle events. From here all my work was pretty straightforward... well I had to fight a little bit with jQuery and IE, but that's another story.

I created the viewlet the usual way and I inserted the JavaScript code with the help of a Python script. To get the list of images in a given folder I used context.atctListAlbum(images=1). I took this idea from, the page template used to view the images in a folder as small thumbnails. I registered the viewlet for Folder content type using a modified version of and the JavaScript file using portal_javascripts, the JavaScript Registry.

The photo gallery is working fine on IE 6.0+, Firefox 1.5+, Safari 2.0+ and Opera 9.0+. Please note that only one gallery is allowed per page. It would be nice to add some effects, but that will have to wait.

The photo gallery viewlet in CompositePack's design view

You can see here the final versions of and

CompositePack rocks! I hope you enjoy it as much as I do.

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