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64 lines
2.9 KiB
Plaintext
64 lines
2.9 KiB
Plaintext
Brltty provides some support for the X11 graphical environment.
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Braille Input from braille device support
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Some braille devices have an integrated braille keyboard. The brltty daemon
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alone can not properly simulate keypresses for the X11 server, because it
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does not know which keyboard layout the latter uses. To get proper keyboard
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simulation, xbrlapi should be started in the background during X session
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startup. By default, xbrlapi also prints the current window's title on the
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braille device. To avoid this (since it could interfere with the output from
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screen readers like Orca), give the -q option to xbrlapi.
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Braille Input from PC keyboard support
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The PC keyboard itself can be used in X11 as a braille keyboard. This can be
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enabled by using the "brai" layout, for instance, the following
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setxkbmap -layout "us,brai" -option "grp:shift_caps_toggle,grp_led:scroll"
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enables both US and braille keyboard layouts to be enabled in X11 (in two
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different XKB groups), and Shift+CapsLock can be used to switch between both
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(i.e. switch between the two XKB groups). The scroll LED will be lit while being
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in braille mode, for sighted people to notice why they get strange output if
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they switch groups by accident. Other shortcuts and LEDs can be used, see the
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XKB documentation. The default keyboard mapping for braille dots is "asdfjkl,",
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but other layouts are available, see the variants in XKB.
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The setxkbmap command above enables it just for the current session. For
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permanent configuration, the two groups have to be configured properly in the
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system. On Debian for instance, this can be achieved by setting the following
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in /etc/default/keyboard:
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XKBLAYOUT="us,brai"
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XKBOPTIONS="grp:shift_caps_toggle,grp_led:scroll"
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By default, the result will be unicode braille patterns, because X11 does not
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know which braille table it should use. To tell X11 the conversion that should
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be performed, use the ttbtest tool to convert your brltty table into an XCompose
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table, for instance:
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ttbtest -i ttb -o XCompose en_US.ttb /tmp/my.XCompose
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The XCompose table can then be enabled by:
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cat /tmp/my.XCompose >> ~/.XCompose
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Screen reading
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--------------
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Brltty is not meant to be able to read a whole graphical environment, as it
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does not have the notion of menus, buttons, etc. The orca screen reader should
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be used instead. Brltty however has a driver to at least review the textual
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elements: edit boxes and terminals. This is particularly interesting for
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reading terminals, since that is what brltty is good at. This can be achieved by
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running a second brltty daemon during X11 session startup:
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brltty -b ba -x as
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This second daemon will connect to the first one throught BrlAPI (thanks to the
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"ba" braille driver), and read the screen via AtSpi (thanks to the "as" screen
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driver). An "a2" driver is also provided for AtSpi2 support.
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