[g-a-devel]Re: Why Can't I use BRLTTY With Gnopernicus

[Mario Lang <mlang delysid org>]

"John J. Boyer" <director chpi org> writes:

> So far it looks like brltty is the more likely, because everytime I press a
> key on my braille keyboard, except for a few, there is a message on the tty
> where I invoked startx that says "Default: sending DKxxxx".

This message is produced whenever the ttybrl module receives
a keycode which is not yet mapped to a corresponding Gnopernicus braille
keycode. Quoting brltty-3.3.1/Documentation/README.Gnopernicus, the
following table lists BRLTTY keypresses and their corresponding Gnopernicus 
actions.

   Command      Binding      Description
   ----------   -----------  -----------
   CMD_LNUP     DK00         Go To Parent
   CMD_HOME     DK01         Go To Focus
   CMD_LNDN     DK02         Go To Child
   CMD_FWINLT   DK03         Go To Previous
                DK04         Repeat Last
   CMD_FWINRT   DK05         Go To Next
                DK01DK02     Do Default Action
   CR_ROUTE     HMSnn        Route Cursor

Note that "Repeat Last" and "Do Default" are currently not mapped, because
we couldn't think of a really good keycode for them.

So, what should work for you is moving left/right and up/down in the
widget hierarchy.  Cursour routing keys, if you have some, should also work.
Everything else is just a question of filling out the case statement
in gnopernicu/braille/libbrl/ttybrl.c in function brltty_brl_glib_cb
to make the corresponding brltty keycodes to Gnopernicus braille keyboard codes.

However, note that this does not really prevent you from using Gnopernicus,
since all the navigation functions are mapped on the computer keypad anyway.

Note that the reason for the small number of mappings is mainly due to
the small number of default braille key to function bindings in Gnopernicus.
At the time I wrote ttybrl.c, the keycombinations listed above were the only
ones defined in Gnopernicus.  It would not have made much sense to
create more mappings, since they wouldn't have invoked anything anyway.

If Braille display support in Gnopernicus increases in flexibility,
it is very easy to add more mappings to ttybrl.c.

-- 
CYa,
  Mario | Debian Developer <URL:http://debian.org/>
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