KbName

>Psychtoolbox>PsychBasic

kbNameResult = KbName(arg)

KbName maps between KbCheck-style key codes and key names.

* If arg is a string designating a key label then KbName returns the
keycodes of the indicated key. Some key label may have multiple keys
assigned on some operating systems and keyboards. Therefore the returned
keycodes may be a vector of multiple keycodes, not just one unique key code.

* If arg is a keycode, KbName returns the label of the designated key.

* If no argument is supplied then KbName waits one second and then
calls KbCheck. KbName then returns a cell array holding the names of
all keys which were down at the time of the KbCheck call. The
one-second delay preceeding the call to KbCheck avoids catching the
<return> keypress used to execute the KbName function.

* If arg is ‘UnifyKeyNames’, KbName will switch its internal naming
scheme from the operating system specific scheme (which was used in
the old Psychtoolboxes on MacOS-9 and on Windows) to the MacOS-X
naming scheme, thereby allowing to use one common naming scheme for
all operating systems, increasing portability of scripts. It is
recommended to call KbName(‘UnifyKeyNames’); at the beginning of each
new experiment script.
CAUTION: This function may contain bugs. Please report them (or fix
them) if you find some.

* If arg is ‘KeyNames’, KbName will print out a table of all
keycodes->keynames mappings.

* If arg is ‘KeyNamesOSX’, KbName will print out a table of all
keycodes->keynames mappings for MacOS-X.

* If arg is ‘KeyNamesOS9’, KbName will print out a table of all
keycodes->keynames mappings for MacOS-9.

* If arg is ‘KeyNamesWindows’, KbName will print out a table of all
keycodes->keynames mappings for M$-Windows.

* If arg is ‘KeyNamesLinux’, KbName will print out a table of all
keycodes->keynames mappings for GNU/Linux, X11.

KbName deals with keys, not characters. See KbCheck help for an
explanation of keys, characters, and keycodes.

Please note that KbName always assumes a US keyboard layout. Changing
the keyboard layout settings in your operating system will have no
effect. If a keyboard with non-US layout is connected, e.g, a german
keyboard layout, then certain keys may not match. E.g., on a german
keyboard, the ‘Y’ key will be reported as ‘Z’ key and the ‘Z’ key will
be reported as ‘Y’ key, because these two keys are interchanged on the
german keyboard wrt. the US keyboard.

There are standard character sets, but there are no standard key
names. The convention KbName follows is to name keys with the primary
key label printed on the key. For example, the the “]}” key is named
“]” because “]” is the primary key label and “}” is the shifted key
function. In the case of labels such as “5”, which appears on two
keys, the name “5” designates the “5” key on the numeric keypad and
“5%” designates the QWERTY “5” key. Here, “5” specifies the primary
label of the key and the shifted label, “%” refines the specification,
distinguishing it from keypad “5”. Keys labeled with symbols not
represented in character sets are assigned names describing those
symbols or the key function, for example the space bar is named
“space” and the apple key is named “apple”. Some keyboards have
identically-labelled keys distinguished
only by their positions on the keyboard, for example, left and right
shift keys. Windows operating systems more recent than Windows 95 can
distinguish between such keys. To name such keys, we precede the key
label with either “left_” or “right_”, to create the key name. For
example, the left shift key is called “left_shift”.

Use KbName to make your scripts more readable and portable, using key
labels instead of keycodes, which are cryptic and vary between different
computers.

For example,

yesKeys = KbName(‘return’);
[a,b,keyCode] = KbCheck;
if any(keyCode(yesKeys))

end;

Linux, OS X, and Windows versions of KbCheck return different keycodes.
You can mostly overcome those differences by using KbName, but with
some complications:

While most keynames are shared between operating systems, not all
are. Some key names are used only on Windows, and other key names are
used only on OSX or on Linux. For a lists of key names common to all
platforms and unique to each see the comments in the body of KbName.m.

KbName will try to use a mostly shared name mapping if you add the
command KbName(‘UnifyKeyNames’); at the top of your experiment script.
At least the names of special keys like cursor keys, function keys and
such will be shared between the operating systems.

Your computer might be able to distinguish between identically named
keys. For example, left and right shift keys, or the “enter” key on
the keyboard and the enter key on the numeric keypad. Which of these
keys it can distinguish depends on the operating system. For details,
see comments in the body of KbName.m.

Historically, different operating systems used different keycodes
because they used different types of keyboards: PS/2 for Windows, ADB
for OS 9, and USB for OS 9, Windows, and OSX. KbCheck on OS X returns
USB keycodes.

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See also KbCheck, KbDemo, KbWait.

Path   Retrieve current version from GitHub | View changelog
Psychtoolbox/PsychBasic/KbName.m