TERMKEY_GETKEY(3)TERMKEY_GETKEY(3)NAME
termkey_getkey, termkey_getkey_force - retrieve the next key event
SYNOPSIS
#include <termkey.h>
TermKeyResult termkey_getkey(TermKey *tk, TermKeyKey *key);
TermKeyResult termkey_getkey_force(TermKey *tk, TermKeyKey *key);
Link with -ltermkey.
DESCRIPTIONtermkey_getkey() attempts to retrieve a single keypress event from the
termkey(7) instance buffer, and put it in the structure referred to by
key. It returns one of the following values:
TERMKEY_RES_KEY
a complete keypress was removed from the buffer, and has been
placed in the key structure.
TERMKEY_RES_AGAIN
a partial keypress event was found in the buffer, but it does
not yet contain all the bytes required. An indication of what
termkey_getkey_force() would return has been placed in the key
structure.
TERMKEY_RES_NONE
no bytes are waiting in the buffer.
TERMKEY_RES_EOF
no bytes are ready and the input stream is now closed.
TERMKEY_RES_ERROR
called with terminal IO stopped, due to termkey_stop(3). In this
case errno will be set to EINVAL.
termkey_getkey_force() is similar to termkey_getkey() but will not
return TERMKEY_RES_AGAIN 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.
Neither of these functions will block or perform any IO operations on
the underlying filehandle. To use the instance in an asynchronous pro‐
gram, see termkey_advisereadable(3). For a blocking call suitable for
use in a synchronous program, use termkey_waitkey(3) instead of
termkey_getkey(). For providing input without a readable filehandle,
use termkey_push_bytes(3).
Before returning, this function canonicalises the key structure accord‐
ing to the rules given for termkey_canonicalise(3).
RETURN VALUEtermkey_getkey() returns an enumeration of one of TERMKEY_RES_KEY, TEM‐
RKEY_RES_AGAIN, TERMKEY_RES_NONE, TERMKEY_RES_EOF or TERMKEY_RES_ERROR.
termkey_getkey_force() returns one of the above, except for
TERMKEY_RES_AGAIN.
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 poll(2)-driven asynchronous program, which may
include mixed IO with other file handles.
// <poll.h> might need this for sigset_t
#define _XOPEN_SOURCE 600
#include <poll.h>
#include <stdio.h>
#include "termkey.h"
static void on_key(TermKey *tk, TermKeyKey *key)
{
char buffer[50];
termkey_strfkey(tk, buffer, sizeof buffer, key, TERMKEY_FORMAT_VIM);
printf("%s\n", buffer);
}
int main(int argc, char *argv[])
{
TERMKEY_CHECK_VERSION;
TermKey *tk = termkey_new(0, 0);
if(!tk) {
fprintf(stderr, "Cannot allocate termkey instance\n");
exit(1);
}
struct pollfd fd;
fd.fd = 0; /* the file descriptor we passed to termkey_new() */
fd.events = POLLIN;
TermKeyResult ret;
TermKeyKey key;
int running = 1;
int nextwait = -1;
while(running) {
if(poll(&fd, 1, nextwait) == 0) {
// Timed out
if(termkey_getkey_force(tk, &key) == TERMKEY_RES_KEY)
on_key(tk, &key);
}
if(fd.revents & (POLLIN|POLLHUP|POLLERR))
termkey_advisereadable(tk);
while((ret = termkey_getkey(tk, &key)) == TERMKEY_RES_KEY) {
on_key(tk, &key);
if(key.type == TERMKEY_TYPE_UNICODE &&
key.modifiers & TERMKEY_KEYMOD_CTRL &&
(key.code.codepoint == 'C' || key.code.codepoint == 'c'))
running = 0;
}
if(ret == TERMKEY_RES_AGAIN)
nextwait = termkey_get_waittime(tk);
else
nextwait = -1;
}
termkey_destroy(tk);
}
SEE ALSOtermkey_advisereadable(3), termkey_waitkey(3), termkey_get_waittime(3),
termkey(7)TERMKEY_GETKEY(3)
