termo/termkey_getkey.3.sh

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cat <<EOF
.TH TERMKEY_GETKEY 3
.SH NAME
termkey_getkey, termkey_getkey_force \- retrieve the next key event
.SH SYNOPSIS
.nf
.B #include <termkey.h>
.sp
.BI "termkey_result termkey_getkey(termkey_t *" tk ", termkey_key *" key );
.br
.BI "termkey_result termkey_getkey_force(termkey_t *" tk ", termkey_key *" key );
.fi
.sp
Link with \fI-ltermkey\fP.
.SH DESCRIPTION
\fBtermkey_getkey\fP attempts to retrieve a single keypress event from the buffer, and put it in the structure referred to by \fIkey\fP. If successful it will return \fBTERMKEY_RES_KEY\fP to indicate that the structure now contains a new keypress event. If nothing is in the buffer it will return \fBTERMKEY_RES_NONE\fP. If the buffer contains a partial keypress event which does not yet contain all the bytes required, it will return \fBTERMKEY_RES_AGAIN\fP. If no events are ready and the input stream is now closed, will return \fBTERMKEY_RES_EOF\fP.
.PP
\fBtermkey_getkey_force\fP is similar to \fBtermkey_getkey\fP but will not return \fBTERMKEY_RES_AGAIN\fP if a partial match is found. Instead, it will force an interpretation of the bytes, even if this means interpreting the start of an Escape-prefixed multi-byte sequence as a literal "Escape" key followed by normal letters.
.PP
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Neither of these functions will block or perform any IO operations on the underlying filehandle. To use the instance in an asynchronous program, see \fBtermkey_advisereadable\fP(3). For a blocking call suitable for use in a synchronous program, use \fBtermkey_waitkey\fP(3) instead of \fBtermkey_getkey\fP().
.PP
The \fItermkey_key\fP structure is defined as follows:
.PP
.in +4n
.nf
typedef struct {
termkey_type type;
union {
long codepoint; /* TERMKEY_TYPE_UNICODE */
int number; /* TERMKEY_TYPE_FUNCTION */
termkey_keysym sym; /* TERMKEY_TYPE_KEYSYM */
} code;
int modifiers;
char utf8[7];
} termkey_key;
.fi
.in
.PP
The \fItype\fP field indicates the type of event, and determines which of the members of the \fIcode\fP union is valid. It will be one of the following constants:
.TP
.B TERMKEY_TYPE_UNICODE
a Unicode codepoint. This value indicates that \fIcode.codepoint\fP is valid, and will contain the codepoint number of the keypress. In Unicode mode (if the \fBTERMKEY_FLAG_UTF8\fP bit is set) this will be its Unicode character number. In raw byte mode, this will contain a single 8-bit byte.
.TP
.B TERMKEY_TYPE_FUNCTION
a numbered function key. This value indicates that \fIcode.number\fP is valid, and contains the number of the numbered function key.
.TP
.B TERMKEY_TYPE_KEYSYM
a symbolic key. This value indicates that \fIcode.sym\fP is valid, and contains the symbolic key value. This is an opaque value which may be passed to \fBtermkey_get_keyname\fP(3).
.PP
The \fImodifiers\fP bitmask is composed of a bitwise-or of the constants \fBTERMKEY_KEYMOD_SHIFT\fP, \fBTERMKEY_KEYMOD_CTRL\fP and \fBTERMKEY_KEYMOD_ALT\fP.
.PP
The \fIutf8\fP field is only set on events whose \fItype\fP is \fBTERMKEY_TYPE_UNICODE\fP. It should not be read for other events.
.PP
To convert the \fIsym\fP to a symbolic name, see \fBtermkey_get_keyname\fP(3) function. It may instead be easier to convert the entire key event structure to a string, using \fBtermkey_snprint_key\fP(3).
.SH "RETURN VALUE"
\fBtermkey_getkey\fP() and \fBtermkey_getkey_force\fP() return one of the following constants:
.TP
.B TERMKEY_RES_NONE
No key event is ready.
.TP
.B TERMKEY_RES_KEY
A key event as been provided.
.TP
.B TERMKEY_RES_EOF
No key events are ready and the terminal has been closed, so no more will arrive.
.TP
.B TERMKEY_RES_AGAIN
No key event is ready yet, but a partial one has been found. This is only returned by \fBtermkey_getkey\fP(). To obtain the partial result even if it never completes, use \fBtermkey_getkey_force\fP().
.SH EXAMPLE
The following example program prints details of every keypress until the user presses "Ctrl-C". It demonstrates how to use the termkey instance in a typical \fBpoll\fP()-driven asynchronous program, which may include mixed IO with other file handles.
.PP
.in +4n
`while read LINE; do echo ".br"; echo "$LINE"; done <demo-async.c`
.in
.nf
.fi
.SH "SEE ALSO"
.BR termkey_new (3),
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.BR termkey_advisereadable (3),
.BR termkey_waitkey (3),
.BR termkey_set_waittime (3),
.BR termkey_get_keyname (3),
.BR termkey_snprint_key (3)
EOF