On Sun, Jan 20, 2008 at 04:27:50PM -0600, Hugo Vanwoerkom wrote:
Wayne Topa wrote:
Kent West(westk@acu.edu) is reported to have said:
Hugo Vanwoerkom wrote:
Kent West wrote:
All I want to do is to detect two keys, say the left- and
right-shift keys, or the < and > keys. For one key, a short "dit"
audio tone would be generated, and for the other key, a longer
"dah" audio tone would be generated. I need to bypass the
keyboard buffer, so that holding down the dit key for two seconds
doesn't generate 30 dits; it should produce dits while the key is
held down, but once the key is let up, the dits should
immediately stop (after finishing the one it's on).
...
This may not be what your looking for either Kent, but...
Install the beep package. Then, using bash, write a program to output
to the case speaker like this.
A="/usr/bin/beep -l 80 -f 1000 ;sleep .1;/usr/bin/beep -d 100 -l 250 -f 1000"
B="/usr/bin/beep -d 100 -l 250 -f 1000 ; sleep .1;/usr/bin/beep -l 80 -r 3 -f 1000"
etc
Turns out that keypress access *is* the hardest. You have that in Qt but
you have to be running in X and within a widget. It's ridiculous to do
all that to find out if a key is pressed.
I have no idea how to find out in low-level programming whether a key is
depressed.
Any kernel savvy people out there?
That's not me, but I'm sure there are many ways to do this in higher
level languages. Here's a bit o' perl that loops, blocks until a key
is pressed, does something with the key and so on. I've used the beep
package mentioned above, and that could likely be used to make the sounds.
#!/usr/bin/perl -w
use strict;
use Term::ReadKey;
ReadMode 4; # put terminal in raw mode
while ( 1 ) {
my $key = ReadKey 0; # no time-out, blocks until a key is pressed
last if $key eq 'q';
print "dot\n" if $key eq 'j';
print "dash\n" if $key eq 'k';
}
ReadMode 0; # restore terminal mode
Perl generally provides a wrapper around kernel and system level routines,
and I'm sure Python and other languages have these same capabiities.
Looking at the OP's description/spec of what's to be done, the above
doesn't do it, but could probably be made to approach it. The ReadKey
function can be given a timeout, so that if no key is pressed it returns
with no return value, and this could be used to detect if a key is held
down (I think...).
Emitting the sounds while this is going on might be a trick. One way
would be to fork another process to make the sounds, and communicate
with it via a pipe to turns the dits and dahs on and off. This may
sound complicated, but it's the Unix Way, and the tools support it
very well.
Just a thought...