[Accessibility-handlers] First draft - Use case for "structure to braille conversion"

Vladimir Bulatov vladimir.bulatov at viewplus.com
Fri Aug 3 15:56:33 PDT 2007


Hello everybody,
here is my take on "structure to braille conversion"

Expert handler should be able to provide braille data for braille display
output by generic AT. Custom braille output is needed, because generic AT has no 
knowledge about how specific data can be represented via braille. Example - 
MathML. There are many different braille codes used to represent mathematics in 
different countries and agencies.
Expert handler should provide a way allow user to select different type
of braille conversion.

There is finite number of possible braille dots patterns because there are only 
6 or 8 possible dots per Braille symbol and usually simple ASCII strings are 
used to communicate Braille.
However, there are a lot of specific ASCII to dots pattern encoding in various 
countries. It make sense to use unicode symbols from 0x2800 to 0x28FF to 
communicate braille pattern to AT. Alternative - communicate braille table to
AT or request current braille table from AT.

There is possible need to have braille output of various level of granularity.
For example at low level of granularity - have overall description of the 
mathematical expression or image and at high level of granularity have
complete braille translation of the whole math expression or list of all labeled 
components of the image.

Some data may need to have more advanced tactile output than braille.
For example graphical data would greatly benefit from being embossed on paper
or 2D braille display and having input device (like touchpad or camera)
which allows user to communicate to computer which parts of graphics
he is interested in. Such interactive functionality should be left to expert 
handler completely. It means, that expert handler have to have interactive
mode and a way for AT to turn this mode on. In such mode AT should provide a way 
to expert handler to produce speech and braille output via AT devices (use the 
same TTS engine or/and braille display)

Vladimir Bulatov




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