Re: [program-l] Re: Developing cross-platform, accessible apps

Excellent points, Ian -- thanks. The XUL framework uses the IAccessible2 API, developed by Mozilla and IBM, and reflected in apps such as Firefox and Thunderbird. It is certainly intended to be cross-platform though by means of custom widgets that implement IA2, rather than native widgets of the platform. XUL apps can provide good accessibility on Windows and Linux, though not on the Mac, unfortunately, because Apple has not supported IA2.


Jamal

On 6/13/2010 11:22 AM, Ian Sharpe wrote:
Hi Jamal

I'm afraid I'm not sure on how accessible this is on the various platforms
but XUL provides the GUI for Mozilla (and guess this includes Firefox?).
When I looked at this way back now, it looked like a cross-platform XML
based UI technology but never had enough time to investigate it properly. I
certainly found Mozilla very accessible on Windows using custom colour
schemes and screen magnification but suspect it was also accessible for
screen reader users since I believe this browser was used by many blind
people. I could be wrong but I got the impression XUL utilized the native
capabilities of whichever platform the app was running on in much the way
you describe.

The other point I'd make is that just because your talking about a desktop
scenario, there's no reason why you still can't use HTML to produce the UI
which can be extremely accessible on all platforms if designed well and
appropriate markup used. If I were asked to produce a cross platform
accessible desktop app now, I'd probably use this approach but that maybe
simply because it's because I very familiar with designing accessible web
applications and wouldn't have to worry about platform specific
implementations of native widgets as you say.

Cheers
Ian





-----Original Message-----
From: program-l-bounce@xxxxxxxxxxxxx [mailto:program-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Jamal Mazrui
Sent: 12 June 2010 15:57
To: programmingblind; program-l@xxxxxxxxxxxxx
Subject: [program-l] Developing cross-platform, accessible apps

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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