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CURSES: Uniform method to read keypad keys and function keys

footloose
footloose asked
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Last Modified: 2013-12-26
Is there a method to write a curses program that handles keypad characters like HOME, PageUp/PageDown, and function keys uniformly across all terminal types ? It should also be able to distinguish between Ctrl-A and up-arrow key.

Following the curses man pages, I tried to do a getch() followed by a switch() statement like this:

   switch( getch() )
   {
      case KEY_F1:
         ...
      case KEY_F2:
         ...
      case KEY_HOME:
         ...
   }


These are the mode settings after initscr().
   noecho();
   cbreak();
   nodelay(stdscr,TRUE);
   keypad(stdscr,TRUE);
   scrollok(stdscr,FALSE);
   attrset(A_ALTCHARSET);

It does not work. getch() does not seem to translate the keystrokes into KEY_xx codes. Worse, if I enable the keypad [ keypad( stdscr, TRUE ); ] the arrow keys generate Ctrl-A, Ctrl-B, etc. which is confused with manually typed Ctrl-A or Ctrl-B.

I tried setting raw() mode on, and that complicates matters: now I have to interpret every keystroke. Some keys produce escape sequences consisting of three to six characters. And that is very terminal-specific too.

Maybe what I should do is to build some kind of lookup table during startup using the terminfo database or some such thing and use it for that session. Is this approach right ?
If not, what is a working solution ?

Don't give me terminal-specific suggestions. Thanks !
Comment
Watch Question

Use the wgetch() routine instead; it returns special token
values (outside the 8 bit range) if the keypad has been
turned on (keypad(win, true) ... Maybe you have to fiddle
with the timeout values though, because the frequency
of the incoming escape sequences to be interpreted
by curses may vary considerably between different
terminals ... check it out.

kind regards,

Jos aka jos@and.nl

ps. don't set raw mode; it inhibits that escape sequence
interpretation.

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