Go Premium for a chance to win a PS4. Enter to Win

x
?
Solved

CURSES: Uniform method to read keypad keys and function keys

Posted on 1997-06-11
1
Medium Priority
?
249 Views
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 !
0
Comment
Question by:footloose
1 Comment
 
LVL 4

Accepted Solution

by:
jos010697 earned 400 total points
ID: 1293388
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.
0

Featured Post

Keep up with what's happening at Experts Exchange!

Sign up to receive Decoded, a new monthly digest with product updates, feature release info, continuing education opportunities, and more.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Introduction: Load and Save to file, Document-View interaction inside the SDI. Continuing from the second article about sudoku.   Open the project in visual studio. From the class view select CSudokuDoc and double click to open the header …
If you use Adobe Reader X it is possible you can't open OLE PDF documents in the standard. The reason is the 'save box mode' in adobe reader X. Many people think the protected Mode of adobe reader x is only to stop the write access. But this fe…
This video will show you how to get GIT to work in Eclipse.   It will walk you through how to install the EGit plugin in eclipse and how to checkout an existing repository.
Despite its rising prevalence in the business world, "the cloud" is still misunderstood. Some companies still believe common misconceptions about lack of security in cloud solutions and many misuses of cloud storage options still occur every day. …

927 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question