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Talk:Accessibility/Handlers/UseCases/Unified/Draft2.01

From The Linux Foundation

GJR's edits to Vladmir's original Braille Use Case

Use Case Author: Vladimir Bulatov

An Expert Handler should be able to provide braille data for braille display output by generic Assisstive Technology (AT). Custom braille output is needed, because generic AT has no knowledge about how specific specialized data can and should be represented via braille. An example is MathML: there are many different braille codes used to represent mathematics that vary from country to country and agency to agency.

An Expert Handler should also provide a means to allow a user to select a different type of braille conversion than that which is normally utilized by a user's refreshable braille display or a tactile graphic achieved via embossing or thermal printing.

There is a finite number of possible braille dot patterns because there are only 6 or 8 possible dots per braille symbol. Simple ASCII strings are usually used to communicate braille. However, there are a lot of specific ASCII-to-dots pattern-encoding used to generate braille that conforms to a natural language's braille conventions.

A far more efficient means of communicating braille patterns to a refreshable braille display or a braille embosser, therefore, is to use the Unicode symbols from 0x2800 to 0x28FF to communicate the braille pattern to the AT. Alternatively, an Expert Handler could communicate via a braille table to AT or could request a specific, specialized braille table be loaded in-process for use by the AT.

There is also a need to have braille output tailored to various level of granularity. For example, at a low level of granularity, the user would receive an overall description of the mathematical expression or image, while at the highest level of granularity, the user would receive a complete braille translation of the whole math expression or list of all labeled components of the image.

Some data may need to be expressed in a more advanced tactile output format than refreshable braille. For example, graphical data would greatly benefit from being embossed on paper or a 2D braille display. Input devices, such as a touchpad or camera, which allow a user to communicate to the computer which parts of the graphic the user is interested in and needs tactilely displayed. Such an interactive functionality should be left exclusively to the Expert Handler. This means, that an Expert Handler must have an interactive mode and a way for an AT to trigger/toggle this mode on. In such a mode, an AT should also provide a way for the Expert Handler to produce more than one output stream -- such as simultaneous speech and braille output -- directly via an AT device which uses the same TTS engine or/and braille display.


Vladimir's Revised Braille Use Case (comprises current text in Draft 2.01)

An Expert Handler should be able to provide braille data for braille display output by generic Assisstive Technology (AT). Custom braille output is needed, because generic AT has no knowledge about how specific specialized data can and should be represented via braille. An example is MathML: there are many different braille codes used to represent mathematics that vary from country to country and agency to agency.

There is a small number of possible braille dot patterns because there are only 6 or 8 possible dots per Braille symbol. Therefore simple ASCII strings are usually used to communicate Braille. However, there are a lot of specific ASCII-to-dots pattern-encoding tables used to generate braille that conforms to a natural language's braille conventions. A far more universal means of communicating braille patterns to a refreshable braille display or a braille embosser, therefore, is to use the Unicode symbols from 0x2800 to 0x28FF to communicate the braille pattern to the AT. Alternatively, an Expert Handler could communicate ASCII strings to AT using an AT's supplied braille table or could request a specific, specialized Braille table be loaded in-process for use by the AT.

There is also a need to have braille output tailored to various levels of granularity. For example, at a low level of granularity, the user would receive an overall description of the mathematical expression or image, while at the highest level of granularity, the user would receive a complete braille translation of the whole math expression or list of all labeled components of the image.

Some data may need to be expressed in a more advanced tactile output format than refreshable braille. For example, graphical data would greatly benefit from being embossed on paper or a 2D braille display. Input devices, such as a touchpad or camera, which allow a user to communicate to the computer which parts of the graphic the user is interested in and needs tactilely displayed. Such an interactive functionality should be left exclusively to the Expert Handler. This means, that an Expert Handler must have an interactive mode and a way for an AT to trigger/toggle this mode on. In such a mode, an AT should also provide a way for the Expert Handler to produce an output stream -- such as speech and/or braille output -- via the same TTS engine or/and braille display which the AT uses.





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