Re: Developing cross-platform, accessible apps

  • From: Jamal Mazrui <empower@xxxxxxxxx>
  • To: programmingblind@xxxxxxxxxxxxx
  • Date: Sat, 12 Jun 2010 14:24:18 -0400

Hi Roopakshi,
I am aware of the Java access API, but unfortunately, I do not think there is sufficient screen reader support for it on Windows. This is more the fault of the screen reader companies than Sun, since the API is strong on the server side.
Window-Eyes, for example, does not support that API at all. JAWS works partially. I hear that NVDA works well. I do not know about System Access or Hal. With the SWT approach, on the other hand, apps can be fully accessible because native widgets are used, including MSAA-integrated controls on Windows.
Thanks for the info about Axtk, which I had not heard about. At first, I thought the name was associated with the cross-platform GUI library called TK, which has poor accessibility, but I see that it is actually wx-related, as you say. 

Jamal

On 6/12/2010 11:53 AM, Roopakshi Pathania wrote:
>
> Hi Jamal,
>
Thanks for the info about Axtk -- I had not heard of it. The name made me first think it was related to the cross-platform GUI library called TK, which has poor accessibility, but I see that it is based on wxWdigets, as you say. 

Jamal



On 6/12/2010 11:53 AM, Roopakshi Pathania wrote:


Hi Jamal,


You left out Java Accessibility API that provides access to Swing based 
applications on all platforms (not completely sure about Mac) through Java 
Access Bridge.
In this regard, the guidelines laid down by IBM on developing a completely 
accessible Java application are quite useful.
http://www-03.ibm.com/able/guidelines/software/accesssoftware.html

I like to point the developers of inaccessible applications to this page.

One more toolkit might be of interest: AxTk.
http://code.google.com/p/axtk/

It is built on wxWidgets and is especially geared towards screen reader users. 
It is also suppose to have text to speech wrapper class supporting a number of 
speech engines.

I’m building my own tools for financial and data analysis, so have looked at 
cross-platform accessible libraries.

Regards
Roopakshi

--- On Sat, 6/12/10, Jamal Mazrui<empower@xxxxxxxxx>  wrote:


From: Jamal Mazrui<empower@xxxxxxxxx>
Subject: Developing cross-platform, accessible apps
To: "programmingblind"<programmingblind@xxxxxxxxxxxxx>, program-l@xxxxxxxxxxxxx
Date: Saturday, June 12, 2010, 8:27 PM
This is to share some points I have
learned about developing cross-platform, GUI-accessible,
desktop apps.  Currently, the key is using programming
libraries that wrap native widgets of the platform. These
native widgets generally implement the main accessibility
API of the platform, much more so than custom widgets.

On Windows, native widgets are most likely to implement
Microsoft Active Accessibility, or  increasingly, User
Interface Automation as it replaces MSAA.  On Linux,
the GTK+ widgets that are native to the Gnome desktop
implement the Assistive Technology Service Provider
Interface. On the Mac, Cocoa-based widgets implement the Mac
Accessibility Protocol.

Thus, a cross-platform library is most likely to create
accessible GUIs if it wraps native widgets of each platform,
rather than defining its own widgets.  A disadvantage
of this approach is that the developer needs to be conscious
of small differences in the behavior of widgets across
platforms, even though wrapping code of the library tries to
minimize such differences.  Besides accessibility, an
advantage of this approach is that widgets have the look and
feel that sighted users are accustomed to experiencing on
each platform.

Sometimes, a GUI library is closely associated with a
programming language that has especially strong support for
that library in wrapper functions and design tools.  A
few language and library combinations that seem to work
particularly well for cross-platform, accessible development
are as follows:

*  Java and the Standard Widget Toolkit
http://www.eclipse.org/swt/

*  Python and wxWidgets
http://wxPython.org

*  C# and the System.Windows.Forms classes of the Mono
Framework
http://mono-project.org

Note that, in this case, the Microsoft .NET Framework
should be used as the runtime environment on Windows in
order to have native widget support.
http://msdn.microsoft.com/en-us/netframework/default.aspx

If others have further info or ideas on this topic, please
share.

Jamal

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