Emacs modifies every event it reads according to
extra-keyboard-modifiers
, then translates it through
keyboard-translate-table
(if applicable), before returning it
from read-event
.
This variable lets Lisp programs “press” the modifier keys on the
keyboard. The value is a character. Only the modifiers of the
character matter. Each time the user types a keyboard key, it is
altered as if those modifier keys were held down. For instance, if
you bind extra-keyboard-modifiers
to ?\C-\M-a
, then all
keyboard input characters typed during the scope of the binding will
have the control and meta modifiers applied to them. The character
?\C-@
, equivalent to the integer 0, does not count as a control
character for this purpose, but as a character with no modifiers.
Thus, setting extra-keyboard-modifiers
to zero cancels any
modification.
When using a window system, the program can press any of the modifier keys in this way. Otherwise, only the CTL and META keys can be virtually pressed.
Note that this variable applies only to events that really come from the keyboard, and has no effect on mouse events or any other events.
This terminal-local variable is the translate table for keyboard
characters. It lets you reshuffle the keys on the keyboard without
changing any command bindings. Its value is normally a char-table, or
else nil
. (It can also be a string or vector, but this is
considered obsolete.)
If keyboard-translate-table
is a char-table
(see Char-Tables), then each character read from the keyboard is
looked up in this char-table. If the value found there is
non-nil
, then it is used instead of the actual input character.
Note that this translation is the first thing that happens to a
character after it is read from the terminal. Record-keeping features
such as recent-keys
and dribble files record the characters after
translation.
Note also that this translation is done before the characters are
supplied to input methods (see Input Methods). Use
translation-table-for-input
(see Translation of Characters),
if you want to translate characters after input methods operate.
This function modifies keyboard-translate-table
to translate
character code from into character code to. It creates
the keyboard translate table if necessary.
Here’s an example of using the keyboard-translate-table
to
make C-x, C-c and C-v perform the cut, copy and paste
operations:
(key-translate "C-x" "<control-x>") (key-translate "C-c" "<control-c>") (key-translate "C-v" "<control-v>") (keymap-global-set "<control-x>" 'kill-region) (keymap-global-set "<control-c>" 'kill-ring-save) (keymap-global-set "<control-v>" 'yank)
On a graphical terminal that supports extended ASCII input, you can still get the standard Emacs meanings of one of those characters by typing it with the shift key. That makes it a different character as far as keyboard translation is concerned, but it has the same usual meaning.
See Keymaps for Translating Sequences of Events, for mechanisms that translate event sequences
at the level of read-key-sequence
.