Challenges to Developing an Android-based PDA


When American Printing House for the Blind and Levelstar undertook the task of redesigning the popular Braille Plus Mobile Manager we decided to adopt Android as the platform. In this session we cover some of the decision process and the challenges we faced in using android to develop a fully-functional Android-based device with full accessibility and support using speech and braille.

We begin by describing the level of accessibility that was available in Android when we began the project. Android 2.was the current version. Talkback was available along with a few other accessibility tools such as the "Talking Dialer". We continue by discussing the accessibility events that drives accessibility in Android. There is no direct interface between the accessibility software, screen reader, and the application. It is up to the application, in Android usually an "activity", to broadcast accessibility events to any "accessibility services" that are interested.

It is noteworthy that Google and the developers of Android have solved quite a few of these issues in Android 4.0 (Ice Cream Sandwich).

Challenges presented include:

Why Change

Why Android

Disadvantages and Challenges

Word Processing and Printing Support

APH serves a population that is largely represented by students and teachers. Students need to be able to compose on their personal device, preferably with braille as a choice, and print out that information. While a day may come when this is no longer the case, for now students need to:

Android 2.3 had very little support for editing and printing. We have added a minimal word processor to the Android distribution for the Braille Plus 18 and plan to continue its development to provide greater support for document types, printers, and embossers.

Audio CODEC Support

The primary need here is support for an audio CODEC (coder/decoder) that supports an encoding used by NLS.

Not only is AMR/wb support required for NLS playback, it also must be plugged into a DRM channel so that encrypted audio can be decoded for playback.

The APH book reader for Android does include support using native libraries ported over from the original Braille Plus Mobile Manager.

Limitations in the Accessibility Framework

This subject comes with some qualifications. Most of these items are from Android 2.3.3. Certainly with Android 4.0 (Ice Cream Sandwich) some of these have been resolved or at least improved upon.

UI elements with no Accessibility Support

Overcoming Some of the Issues

We were able to overcome some of the limitations presented by the 2.3.3 accessibility framework. In some cases combining an input method allowed better access to text. We use some special "widgets" to help cache and manage UI elements so that information can be repeated and made available for other purposes.

It was necessary to put our own version of the web view into the framework for the version of Android on the Braille Plus 18. Without it one could, for example, read a list of email messages and even reply to them, but not read them. This is the same reason several developers have developed special "accessible" mail clients for Android. Using a special web view in the framework means we only had to fix it once rather than develop special apps to replace the ones included in Android.

Web Browser

A number of "talking" browsers have been developed all with functionality that is limited to one degree or another. Progress continues but this is a complex undertaking and there is a lot to do and many decisions that must be made regarding the best way to provide access and functionality to web applications that are sometimes quite complex. We and many others are continuing to work on this.

Braille Support

Braille Plus 18 Braille Support