# I am stuck and can't find a simple and portable way to trap
# the ESC key. Any
# pointers, help is most appreciated. The code I have now is -
···
From: I G [mailto:rubycrazy@gmail.com] :
#
# require 'Win32API'
# def getchar
# char = Win32API.new("crtdll", "_getch", [], 'L').call
# if char == 27 # ESC key
# exit
# end
# end
#
# i = 0
# loop do
# print "#{i+=1}, "
# getchar
# end
can you try this sample?
C:\family\ruby\key_press>cat -n a1d.rb
1 #------------------------------
2 require 'Win32API'
3
4 @@kbhit = Win32API.new("msvcrt", "_kbhit", [], 'I')
5 @@getch = Win32API.new("msvcrt", "_getch", [], 'I')
6
7 def capture_key
8 unless @@kbhit.call.zero?
9 yield @@getch.call
10 end
11 end
12
13 KEY_Esc = 27
14 $stdout.sync=true
15
16 i=0
17 loop do
18 capture_key do |key|
19 puts "keypressed: value #{key}, char #{key.chr}" if $DEBUG
20 if key == KEY_Esc
21 puts "Escaping key pressed. Exiting..." if $DEBUG
22 exit
23 end
24 end
25 sleep 1 #delay it since it's too fast
26 puts "#{i+=1}"
27 end
28 #------------------------------
C:\family\ruby\key_press>ruby -d a1d.rb
1
2
3
4
keypressed: value 117, char u
5
keypressed: value 101, char e
6
7
8
keypressed: value 119, char w
9
10
keypressed: value 120, char x
11
12
keypressed: value 27, char ?
Escaping key pressed. Exiting...
Harry, I have tried HighLine but that's not what I want (or am I making a
mistake here?). I am trying to solve the problem - ** "Display series of
numbers (1,2,3,4, 5….etc) in an infinite loop. The program should quit if
someone hits a specific key (Say ESCAPE key)."
Somehow I want to keep checking in a thread (this should be non-blocking)
for the ESC key press. Once ESC is pressed my program terminates. Right now,
my thread code blocks till I press ESC key, as you can see here -
require 'Win32API'
def getchar
char = Win32API.new("crtdll", "_getch", , 'L').call
if char == 27 # ESC key
exit
end
end
i = 0
loop do
print "#{i+=1}, "
getchar
end
What should I do? Thanks.
···
On 3/16/07, Harry <ruby.hardware@gmail.com> wrote:
>
> I am stuck and can't find a simple and portable way to trap the ESC key.
Any
> pointers, help is most appreciated.
>
Will this do it?
Harry, I have tried HighLine but that's not what I want (or am I making a
mistake here?). I am trying to solve the problem - ** "Display series of
numbers (1,2,3,4, 5….etc) in an infinite loop. The program should quit if
someone hits a specific key (Say ESCAPE key)."
Somehow I want to keep checking in a thread (this should be non-blocking)
for the ESC key press. Once ESC is pressed my program terminates. Right now,
my thread code blocks till I press ESC key, as you can see here -
require 'Win32API'
def getchar
char = Win32API.new("crtdll", "_getch", , 'L').call
if char == 27 # ESC key
exit
end
end
i = 0
loop do
print "#{i+=1}, "
getchar
end
What should I do? Thanks.
Change your operating system, or don't use threads with blocking keyboard I/O. It doesn't work on Windows. For your code above (which doesn't use threads) you could call the Win32 function "_kbhit" before calling "_getch". In a thread you could do the same in a busy loop, but don't forget to sleep a little bit inside the loop.
