On Sun, Feb 24, 2019 at 1:39 AM Cameron Simpson <c...@cskk.id.au> wrote:
> It looks like the resizeterm() function updates the curses _internal_
> records of what it believes the physcial terminal size to be. When you
> physically resize a terminal the processes within it receive a SIGWINCH
> signal, and those which pay attention to that signal should then consult
> the terminal to find out its new size.
>
> The curses library notices this signal, and calls resizeterm() to update
> its own internal idea of the terminal size so that it knows how to draw
> correctly on the screen. It does _not_ change the terminal; it changes
> curses' beliefs _about_ the terminal.
>
> If you call resizeterm() yourself you will cause curses to act from then
> on as though the physcial terminal has the size you supplied. That may
> make for bad rendering if that size does not match reality (consider
> cursor motions "from the right edge" or "from the bottom edge" - their
> sizes are computed from where curses thinks those edges are).
>
> Test the function curses.is_term_resized(nlines,ncols), whose doco says:
>
> Return True if resize_term() would modify the window structure, False
> otherwise.
>
> The is_term_resized() function looks up the current physical size and
> reports False if that matches curses current beliefs, and True if it
> does not match, meaning that the physical size has changed since curses
> last set up its beliefs (for example, in some environment where the
> resize _doesn't_ propagate a SIGWINCH to the process using curses, so it
> hasn't noticed).
>
> Does this clarify things for you?
What you say makes sense and supports much of what I had concluded
from my coding experiments. However, I still cannot get the function
call, curses.resizeterm(), to do anything meaningful, which suggests
that I still do not truly understand its usage. I created the
following script to test things out:
#!/usr/bin/env python3
import curses
def start_cli(stdscr):
max_y, max_x = stdscr.getmaxyx()
stdscr.clear()
stdscr.border()
stdscr.addstr(2, 2, "This is the beginning!")
stdscr.refresh()
while True:
char = chr(stdscr.getch())
if char in 'Qq':
return
if curses.is_term_resized(max_y, max_x):
max_y, max_x = stdscr.getmaxyx()
stdscr.clear()
stdscr.addstr(max_y//2, max_x//2, "You resized the terminal!")
stdscr.addstr(max_y//2 + 1, max_x//2, "Resizing your
window -- NOW!")
#curses.resizeterm(max_y, max_x)
stdscr.border()
stdscr.refresh()
if __name__ == '__main__':
curses.wrapper(start_cli)
Notice that I have "curses.resizeterm( ..." commented out. Whether I
comment it out or leave it in, the behavior I observe while manually
resizing my terminal window is the same. The stdscr.border() still
tracks around the limits of the full terminal screen size. I had also
tried not adding stdscr.border() in the if block, thinking that maybe
curses.resizeterm() would redraw the border once I refreshed the
screen, but that did not happen.
So what am I misunderstanding? Can someone show me a code snippet
that I can run which will demonstrate the usefulness and usage of
curses.resizeterm()?
TIA!
--
boB
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