How to get KeyPressed() or kbhit() in ncurses?
Ian R Matters
of checking the input buffer to see if anything is there prior to using a
getchar() or whatever. I cannot find something like KeyPressed() or
kbhit() in the documentation. How should I do it?
Thanks,
Ian Matters (Ian.M...@anu.edu.au)
Rasmus Lerdorf
>I'm trying to write some basic interactive routines using and need a way
>of checking the input buffer to see if anything is there prior to using a
>getchar() or whatever. I cannot find something like KeyPressed() or
>kbhit() in the documentation. How should I do it?
Look at the source to ncurses. In particular libgetch.c. You will
find that ncurses uses a 32 byte FIFO and that there are 3 queue numbers
that will help you figure out how many chars are in the queue. _fifohead,
_fifotail and _fifopeek. You will need to "extern" the SP structure in
your program and then you can simply check SP->_fifohead and SP->_fifotail
to see if there is anything in the type-ahead buffer. If SP->_fifohead is
-1 it is empty.
Note that ncurses1.8.6 is now available at ftp.netcom.com:/pub/zmbenhal/ncurses.
*Rasmus*
Bjorn Ekwall
> Thanks,
> Ian Matters (Ian.M...@anu.edu.au)
Try this one...
==============================================================================
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
/*
* Return 1 (true) if there are any unread characters, 0 (false) otherwise
*/
int
kbhit(void)
{
struct timeval timeout;
fd_set readfds;
int how;
/* look only at stdin (fd = 0) */
FD_ZERO(&readfds);
FD_SET(0, &readfds);
/* poll: return immediately */
timeout.tv_sec = 0L;
timeout.tv_usec = 0L;
how = select(1, &readfds, (fd_set *)NULL, (fd_set *)NULL, &timeout);
/* Change "&timeout" above to "(struct timeval *)0" ^^^^^^^^
* if you want to wait until a key is hit
*/
if ((how > 0) && FD_ISSET(0, &readfds))
return 1;
else
return 0;
}
=============================================================================
Bjorn Ekwall == bj...@blox.se
Zeyd M. Ben-Halim
>irm...@huxley.anu.edu.au (Ian R Matters) writes:
>
>>I'm trying to write some basic interactive routines using and need a way
>>of checking the input buffer to see if anything is there prior to using a
>>getchar() or whatever. I cannot find something like KeyPressed() or
>>kbhit() in the documentation. How should I do it?
>
>Look at the source to ncurses. In particular libgetch.c. You will
>find that ncurses uses a 32 byte FIFO and that there are 3 queue numbers
>that will help you figure out how many chars are in the queue. _fifohead,
>_fifotail and _fifopeek. You will need to "extern" the SP structure in
>your program and then you can simply check SP->_fifohead and SP->_fifotail
>to see if there is anything in the type-ahead buffer. If SP->_fifohead is
>-1 it is empty.
GACK, DON'T. man curs_inopts and lookup nodelay(). Also you might want to
read through doc/manual.doc
>Note that ncurses1.8.6 is now available at ftp.netcom.com:/pub/zmbenhal/ncurses.
OOPS, the cat is out of the bag :-) I'll announce as soon I've set the mailing
list up.
Zeyd
--
---
Zeyd M. Ben-Halim zmbe...@netcom.com
NCURSES is available from ftp.netcom.com:pub/zmbenhal/ncurses
Current version is 1.8.5
Ruurd Pels
>>>I'm trying to write some basic interactive routines using and need a way
>>>of checking the input buffer to see if anything is there prior to using a
>>>getchar() or whatever. I cannot find something like KeyPressed() or
>>>kbhit() in the documentation. How should I do it?
>>Look at the source to ncurses. In particular libgetch.c. You will
>>find that ncurses uses a 32 byte FIFO and that there are 3 queue numbers
>>that will help you figure out how many chars are in the queue. _fifohead,
>>_fifotail and _fifopeek. You will need to "extern" the SP structure in
>>your program and then you can simply check SP->_fifohead and SP->_fifotail
>>to see if there is anything in the type-ahead buffer. If SP->_fifohead is
>>-1 it is empty.
Ugh!!!
>You are not going to tell us that this is really the way to do it,
>aren't you??
Here's the trick I use. It's not exactly kbhit(), but it insures that any
process keeps running. Initialization:
.
.
halfdelay(10); // <================= !!!!
.
.
No flames! This is not yet production ripe code. I'll explain. We did set
halfdelay to 10, which amounts to 1 second. What happens inside the
curses library is that the process is put to sleep for a maximum time
of one second or until a key is pressed. Then, if we receive an escape
character, we turn down the delay to zero, and immediately look if there
is another key coming. If it's another <Esc>, then return <Esc> as the
key pressed, else, you're in Meta-Sends-Esc-Prefix mode, so, we convert
the second key received into a meta-key by turning on bit 7.
int Application::GetACharacter()
{
int firstchar;
int nextchar;
if ((firstchar = getch()) == 0x1b)
{
halfdelay(0);
nextchar = getch();
if (nextchar != 0x1b)
{
// This is not a single escape character! So, this
// is meta as Esc-prefix...
firstchar = nextchar | METABIT;
}
halfdelay(10);
}
return firstchar;
}
In my main loop, there is a switch block as follows:
void Application::GetInputEvent(InputEvent& event)
{
int thechar;
if (!quitting && !terminate_self)
{
thechar = GetACharacter();
switch (thechar)
{
case ERR:
{
Idle(); // <=========== !!!
break;
}
.
.
case KEY_IC:
case KEY_IL:
{
if (insmode)
{
insmode = False;
curs_set(2);
}
else
{
insmode = True;
curs_set(1);
}
titlebar->SetModeIndicator(insmode);
break;
}
.
.
}
Update();
event.key = thechar;
event.insmode = insmode;
.
.
}
--
Grtz, RFP ;-)
|o| Ruurd Pels, Kamgras 187, 8935 EJ Leeuwarden, The Netherlands |o|
|o| ru...@autpels.nl EU.net!sun4nl!wtrlnd!maxine!autpels!ruurd |o|
Jim Harkins
> halfdelay(10); // <================= !!!!
Having spent more time than I care to admit porting DOS code to Unix
machines I must say that people who use C++ comments in C code should
be taken out and shot.
jim
--
"I want to die peacefully in my sleep like my grandfather. Not screaming
in terror like his passengers."
Jim Harkins jhar...@netcom.com
San Diego, CA.
Zeyd M. Ben-Halim
>
>>>>I'm trying to write some basic interactive routines using and need a way
>>>>of checking the input buffer to see if anything is there prior to using a
>>>>getchar() or whatever. I cannot find something like KeyPressed() or
>>>>kbhit() in the documentation. How should I do it?
>
>>>Look at the source to ncurses. In particular libgetch.c. You will
>>>find that ncurses uses a 32 byte FIFO and that there are 3 queue numbers
>>>that will help you figure out how many chars are in the queue. _fifohead,
>>>_fifotail and _fifopeek. You will need to "extern" the SP structure in
>>>your program and then you can simply check SP->_fifohead and SP->_fifotail
>>>to see if there is anything in the type-ahead buffer. If SP->_fifohead is
>>>-1 it is empty.
>
>Ugh!!!
>
>>You are not going to tell us that this is really the way to do it,
>>aren't you??
It is definitely NOT the way to do it. Use nodelay(), it will return ERR if
no input is available.
Zeyd
--
---
Zeyd M. Ben-Halim zmbe...@netcom.com
NCURSES is available from ftp.netcom.com:pub/zmbenhal/ncurses
Current version is 1.8.6