Make Your Application Accessible with Accerciser
When sighted users see Limelite's UI, it is obvious to them what the relationship is between the labels. For example, it is clear that the Artist label denotes the fact that Edith Piaf is the performing artist of the current track. This is clear because of the table-like spatial layout of the labels: on the left are the field names and on the right are the field contents.
A screen reader will have trouble conveying this relationship between the two labels to blind users. AT-SPI exposes all of these labels as a flat collection, and GAIL has no way of automatically determining the labels' relationship to each other.
For this reason, such relationships need to be defined explicitly by the application author. If the application's UI was defined via Glade or GtkBuilder, we could easily declare the proper relationships in the Accessibility tab in each label's properties. If our user interface is written pragmatically, we will have to use ATK's API.
With Limelite as an example, the label containing the Artist string needs to have a “label-for” relationship with the label holding Edith Piaf, and the Edith Piaf label in turn needs to have a “labeled-by” relationship with the label holding Artist. Similar reciprocal relationships need to be defined for the Title and Album fields.
Finally, in the Accessible section in Accerciser's Interface Viewer plugin, we could verify that the defined relationships are coming down the wire and are provided to the assistive technology.
It is hard to separate usability from accessibility; more often than not, the two terms are synonymous and require your sound judgment. But, if you keep a few simple principles in mind, developing an accessible application is an easy and straightforward task. Tools such as Accerciser allow you to review your program's interface from the assistive technology side and make informed choices in interface design.
Accerciser's Web Site: live.gnome.org/Accerciser
GNOME Accessibility QA: developer.gnome.org/projects/gap/testing/index.html
Keyboard Navigation for GNOME: developer.gnome.org/projects/gap/keyboardnav.html
ATK API Documentation: library.gnome.org/devel/atk/unstable/index.html
Eitan Isaacson currently lives in Seattle, Washington. Eitan is a regular contributor to Orca and is the developer and maintainer of Accerciser. Eitan's passions include sipping high-mountain oolong tea and talking politics.