NCurses Refresh

Question

I have a small ncurse program I'm running, but the output doesn't seem to show up unless I stick the wrefresh() in a while loop.

Is there some buffering going on or something? I tried other refresh functions in the library and fflush with stddout (which I don't think makes sense, but worth a try), but nothing seems to work.

A second small question: to make getch() non-blocking we need to call nodelay(win,TRUE), right?

  void main() { initscr(); start_color(); init_pair(1,COLOR_YELLOW,COLOR_CYAN); WINDOW *win = newwin(10,10,1,1); wbkgd(win,COLOR_PAIR(1)); wprintw(win,"Hello, World."); wrefresh(win); getch(); delwin(win); endwin(); }

I added the following code: while(ERR == getch()) { wrefresh(win); ++ctr; } and the output looks good, but I still don't understand why it doesn't initially display without looping. — Tim
– Tim, Commented Sep 27, 2010 at 23:55

caf · Accepted Answer · 2010-09-28 00:44:26Z

23

You are not supposed to mix operations on stdscr and windows created with newwin(). getch() operates on stdscr, so that is your problem. Replace that call with

wgetch(win);

(getch() is causing stdscr to be dumped over the top of your other window, and because that happens so quickly it looks like the other window never got displayed at all).

answered Sep 28, 2010 at 0:44

caf

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4 Comments

Tim Over a year ago

Right you are. Thanks a bunch! Sorry, but I need to ask one more: when you call a function that operates on a window does it set focus to that window if there is such a thing as focus?

caf Over a year ago

@Tim: The hardware cursor is left at the location of the cursor in the window that you last refreshed, but that's really the only kind of "focus".

Craig Over a year ago

If you need independent overlaping windows you should look at the panels library that is part of ncurses.

Lothar Dec 11, 2024 at 23:26

I don't understand the design. What has input to do with a window (at least when we don't use echo). Also the window that receives the key depends on the key, at least in modern designs where the key travels down and up a hierarchy. How is this supposed to be implemented?

JOTN · Accepted Answer · 2010-09-27 23:36:04Z

That's working as designed. That allows you to completely redraw your next screen but only the parts that actually changed get sent to the terminal at refresh time. This isn't such a big deal these days but made a big difference when terminal connections were relatively slow.

Thanks for the reply. I understand that's the case, but I don't see anything but a blank screen. How do I get the window and text to appear initially without repeatedly calling wrefresh()?

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