In this second part of my post of on making kivy apps accessible I would like to describe some of the existing libraries and APIs we can model our accessibility features upon. Last week we identified that the main obstacle for creating accessible kivy apps is a missing module that could communicate the widget states to screen-readers. I explored other frameworks that may have tried to solve these problems before us and will discus one such project in particular.
Kivy includes pygame as one of the supported window providers. While looking for accessible apps in Python I found a GUI engine for pygame called OcempGUI. As a part of this project they also worked upon an accessibility module named Papi:
Papi, the Python Accessibility Programming Interface, is a Python wrapper around the GNOME ATK toolkit. It allows a developer to make python objects and applications easily accessibility aware without the need to install PyGTK and the GNOME accessibility components. Instead it only depends on ATK and – on the developers behalf – the ATK/AT-SPI bridge shipped with AT-SPI.
Papi is not limited to the apps you can build with OceampGUI graphical user interfaces but can help support accessibility for any python object. Here’s an example accessible app using Papi:
I created a gist as I couldn’t find a way to embed a Sourceforge file but you can find the complete project there. You can also read more about Papi and OcempGUI on their website. Unfortunately, the project looks like that it is no longer in active development. It’s last release was in 2008.
Assuming that we can build upon this module we’d be able to support accessible Kivy apps on Windows and Linux. We are still left with taking care of OS X Accessibility and also on the mobile devices.
MacOS has a very good accessibility support but only when you are writing Cocoa or Carbon apps. In order to provide a similar level of accessibility support you would likely need to hack around a bit. With inputs from our folks at #macdev on freenode, I set out to do just that. They suggested that I could subclass
NSApplication and implement the
NSAccessibility protocol within the Kivy app. This would involve creating an hierarchy of fake UI objects that provide accessibility implementations as on a Cocoa app. I did make some progress with by using our in-house project — PyObjus to access AppKit frameworks and subclass objective-c classes. But the situation became a little to overwhelming for me to handle within this one week and I haven’t succeeded in creating a working proof of concept as yet.
Fortunately, Apple folks have recently launched a new API starting OS X 10.10 that includes a
NSAccesibilityElement class. I am hoping that this would help avoid creating fake UI objects to implement their accessibility protocols. Here are a couple of examples demonstrating that but I haven’t tried them out yet. Need to get access to their beta versions first. You can also watch their WWDC 2014 session videos on Accessibility on OS X describing it.
We are still left with discussing about the mobile platforms. Here are links to the relevant docs pages for Android (http://developer.android.com/guide/topics/ui/accessibility/apps.html#custom-views) and iOS (https://developer.apple.com/library/ios/documentation/UserExperience/Conceptual/iPhoneAccessibility/Accessibility_on_iPhone/Accessibility_on_iPhone.html). I would like use these bookmarks when I dive deeper into exploring mobile accessibility APIs. However this week, I plan to go back to my original plan and continue the Plyer work from where I left off.