Omeka Plugins and Development
If you’re following my Twitter feed, you probably know that I’ve been ecstatic about a fairly new content management system for Digital Humanists creating digital archives. The web software is called Omeka, and it’s out of the Center for Digital Humanities at George Mason University in Virginia.
Omeka has a rich API (application programming interface) that lets developers and creatives alike create awesome plugins and additional content that flows right along side of the CMS. I have been actively developing Omeka plugins for the past academic year at my university in hopes of making Omeka more accessible to visually impaired people accessing the Omeka archives. The development was sponsored by two grant-related projects that I’m involved with. The first project is LookListenTouch.org which I worked for Fall 2009, and BrailleSC.org that I’m currently working on.
People who are visually impaired generally access websites using screen reading software like JAWS or Apple’s screen reader VoiceOver. This software reads aloud what’s on the screen, but screen readers don’t work well with certain web content, namely Adobe Flash, JavaScript and Java applets. Fortunately, Omeka’s front-end doesn’t rely on any of the technologies, making it pretty accessible out-of-the-box. However, the accessibility plugins I’ve developed expand on the universal design model, making Omeka even more accessible.
The first of the plugins is an Access Keys plugin. This plugin lets the administrator assign Access Keys, which are one-character keyboard shortcuts, to basic Omeka functionality, such as go to the home page, browse by items, browse by collections, skip to next item, skip to previous item, and skip directly to the content. Normally people accessing websites with a screen reader need to listen to a list of menu items each and every time they listen to a page being read, but with the Access Keys model, they can memorize a set of keys, then jump to any page they wish to go to. For example, if you wanted to go to the search page, you can press Control + S and go directly to the search page in Omeka.
Access Keys can provide a ton of usability for user accessing a particular website, making navigation easier than ever before. The thing is, Access Keys have been around since around 1999 — why haven’t they been used before? Well, I’d suggest that’s partially because different web browsers use different modifier keys (i.e. pressing control, command, or shift before pressing the access key in order to activate a link). That’s why BrailleSC.org and LookListenTouch.org is advocating the standardization of modifier keys across different browsers, operating systems, and versions of browsers. This would make life easier for users and developers alike.
Continuing on the idea of Access Keys, I’ve also developed a custom Access Keys plugin that will allow an Omeka administrator to specify up-to 10 URLs and Access Keys that will be available from any page inside of Omeka. For example, you could go to Google.com by pressing Control + G.
Of course, Access Keys are limited to the number of letters and numbers available on the keyboard, so that’s 26 + 10 = 36 available keys. Symbols are not available for assigning Access Keys, and remember that if the shortcut assigned is also a shortcut for the web browser (i.e. in Internet Explorer Control + B is for bookmarking pages), then the assignment will overwrite the browser functionality.
The Last plugin that I’ve completed is one called “TextZoom” that, like its name implies, lets the user enlarge the text on the page. When the admin enables this plugin, they also can specify Access Keys for the enlargement functions. There is five levels of enlargement: default, small, medium, large, and extra large. When a user selects any of the enlargement levels, the settings are automatically remembered for 30-days using a cookie, so when they visit the site again, the text will automatically be enlarged for them. The user can then press the default option to go back to the default site and remove the cookie from their browser.

There are other plugins that I’m working on, including a Google Analytics plugin that will let an administrator look at current website tracking information right from within the admin pages.
Where Can You Get The Plugins?
I have the three plugins mention in detail above available for download at BrailleSC.org/development. I also have the source listed on my own development wiki at CoryBohon.com/development. The plugins are completely open source, so if you wish to take the source code an improve it you can under the terms of the included GNU public license.
If you have any questions about the plugins, you can email me directly at cory [at] corybohon [dot] com or cory [at] braillesc [dot] org.








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