Curses Windowing Example

.gitignore

demo
*.swp

demo.c

#include <ncurses.h>
#include <unistd.h>

void draw_borders(WINDOW *screen) {
  int x, y, i;

  getmaxyx(screen, y, x);

  // 4 corners
  mvwprintw(screen, 0, 0, "+");
  mvwprintw(screen, y - 1, 0, "+");
  mvwprintw(screen, 0, x - 1, "+");
  mvwprintw(screen, y - 1, x - 1, "+");

  // sides
  for (i = 1; i < (y - 1); i++) {
    mvwprintw(screen, i, 0, "|");
    mvwprintw(screen, i, x - 1, "|");
  }

  // top and bottom
  for (i = 1; i < (x - 1); i++) {
    mvwprintw(screen, 0, i, "-");
    mvwprintw(screen, y - 1, i, "-");
  }
}

int main(int argc, char *argv[]) {
  int parent_x, parent_y, new_x, new_y;
  int score_size = 3;

  initscr();
  noecho();
  curs_set(FALSE);

  // set up initial windows
  getmaxyx(stdscr, parent_y, parent_x);

  WINDOW *field = newwin(parent_y - score_size, parent_x, 0, 0);
  WINDOW *score = newwin(score_size, parent_x, parent_y - score_size, 0);

  draw_borders(field);
  draw_borders(score);

  while(1) {
    getmaxyx(stdscr, new_y, new_x);

    if (new_y != parent_y || new_x != parent_x) {
      parent_x = new_x;
      parent_y = new_y;

      wresize(field, new_y - score_size, new_x);
      wresize(score, score_size, new_x);
      mvwin(score, new_y - score_size, 0);

      wclear(stdscr);
      wclear(field);
      wclear(score);

      draw_borders(field);
      draw_borders(score);
    }

    // draw to our windows
    mvwprintw(field, 1, 1, "Field");
    mvwprintw(score, 1, 1, "Score");

    // refresh each window
    wrefresh(field);
    wrefresh(score);
  }

  endwin();

  return 0;
}

Makefile

CFLAGS=-Wall
LDFLAGS=-lncurses

all: demo

clean:
	rm -rf demo

There is 100% CPU usage because there is no usleep being used, which is normally common in such loops.

While that would be an improvement over the original example, my advice is:

1. In a curses-based program, don't use usleep() where napms() will suffice. usleep() introduces a POSIX dependency, while napms() is native to curses, so the app may still be portable to non-POSIX systems.
2. Don't use napms() where a blocking getch() will do. Most curses apps will and should spend most of their time in an idle loop waiting on user input, so you may as well let getch() do the work of idling. In the case of this example, even resize events are reported as KEY_RESIZE key events by ncurses and PDCurses. And even in cases where a non-blocking getch() is needed, you can often rely on mechanisms like halfdelay() or timeout() instead of resorting to an explicit napms().