How box() is adopting max width after resizing terminal

Question

I don't know how reexecuting the function box() is adopting max width automatically and here is test code :

getmaxyx(stdscr,y,x);
      WINDOW *titleWin = update_title_win(NULL,2,x,0,0);
      while((ch = getch()) != 27) {
          if(ch == KEY_RESIZE) {
              update_title_win(titleWin);
          }
      }

update_title_win() code :

WINDOW* update_title_win(WINDOW *win, int height, int width, int y, int x)
{
    if(!win)
        win = newwin(height,width,y,x);
    box(win,0,0);
    refresh();
    wrefresh(win);
    return win;
}

score 1 · Accepted Answer · answered Sep 17 '19 at 20:14

The ncurses library uses resizeterm to do the adjustments when getch returns KEY_RESIZE. That function will reduce the size of windows if the (terminal/screen) shrinks, but the behavior when the screen increases in size is less apparent.

The manual page for resizeterm does not mention this, but a comment in the source code explains the behavior:

/*
 * If we're increasing size, recursively search for windows that have no
 * parent, increase those to fit, then increase the contained window, etc.
 */

A window created with newwin has no parent (unlike something made with subwin). Since the titleWin started off with the full width of the screen, as the screen width changes, ncurses will attempt to keep the title window full-width.

How box() is adopting max width after resizing terminal

1 Answers1