I agree that IA2 is a good, practical API, if only it were more widely supported.
With the development approaches I was suggesting, one would not need to consciously implement support for the various APIs. Instead, the best API on each platform would naturally be supported due to the use of widgets that are native to that platform, which the platform developer has tried to integrate with the main accessibility API of that platform -- which is usually also designed by the same platform developer.
Jamal On 6/12/2010 11:41 AM, Chris Hofstader wrote:
This is a pretty good start at strategies for cross platform accessibility development. The four accessibility API are, however, different enough to make wrapping code for the different OS very difficult as there are some obvious and other nuanced techniques that simply do not exist in all of them. If I was launching a new project on GNU/Linux or Windows, I would use the iAccessible2 API. The iAccessible2 API, developed by Aaron Leventhal and some others at IBM, intends to harmonize at least two OS and, if I remember correctly, it is how AT communicates with programs like OpenOffice and Thunderbird. IBM has given iAccessible2, trademark and all, to the Linux Foundation so it has a good chance of being maintained moving forward. This, of course, leaves us with the Macintosh. In relatively standard behavior for Apple, they refused to work with IBM on iAccessible2 and insists on going it alone with their proprietary accessibility framework. There aren't 1:1 relationships between iAccessible2 and Apple accessibility API at either the event or function level so supporting it along with the other platforms can be a nightmare and a rats nest of code trying to square peg on access API into another. I do not know of any software written that is accessible on all three. Apple is the one that is the most broken. cdh On 06/12/2010 10:57 AM, Jamal Mazrui wrote: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 __________ View the list's information and change your settings at //www.freelists.org/list/programmingblind
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