Redraw delay when using getch() with timeout() set - c

Question

I have ncurses program where I need instant response to user input and term resize and 1 sec delay between redraws.
By using sleep(1) I got instant redraw on startup and term resize but 1 sec delay on user input.
By using timeout(1 * 1000) and getch() I get instant response for input but 1 sec redraw delay on startup and resize.
Here is example program to demonstrate the problem:
#include <stdlib.h>
#include <stdio.h>
#include <signal.h>
#include <ncurses.h>
static sig_atomic_t resize;
void sighandler(int sig) {
if (sig == SIGWINCH)
resize = 1;
}
int main(int argc, char *argv[]) {
double delay = 1.0;
char key = ERR;
WINDOW *testwin;
if (argc > 1)
delay = strtod(argv[1], NULL);
signal(SIGWINCH, sighandler);
initscr();
timeout(delay * 1000);
testwin = newwin(LINES, COLS, 0, 0);
while (key != 'q') {
if (key != ERR)
resize = 1;
if (resize) {
endwin();
refresh();
clear();
werase(testwin);
wresize(testwin, LINES, COLS);
resize = 0;
}
box(testwin, 0, 0);
wnoutrefresh(testwin);
doupdate();
key = getch();
}
delwin(testwin);
endwin();
return EXIT_SUCCESS;
}

Answer 1

I'm thinking about select and/or threads: one thread could monitor the resize while the other one will wait for user input.
You can synchronize threads with a select, which can wait on multiple file descriptors: for example you can write on a pipe when you detect an event to wake-up the main process. Cool thing is you can also set a timeout to be woken-up even if no event happened (then you can put a timeout of one second to trigger the redraw).

Answer 2

I managed to solve the resize delay by removing clear();
#include <stdlib.h>
#include <stdio.h>
#include <signal.h>
#include <ncurses.h>
static sig_atomic_t resize;
void sighandler(int sig) {
if (sig == SIGWINCH)
resize = 1;
}
int main(int argc, char *argv[]) {
double delay = 1.0;
char key = ERR;
WINDOW *testwin;
if (argc > 1)
delay = strtod(argv[1], NULL);
signal(SIGWINCH, sighandler);
initscr();
timeout(delay * 1000);
testwin = newwin(LINES, COLS, 0, 0);
while (key != 'q') {
key = getch();
if (key != ERR)
resize = 1;
if (resize) {
endwin();
refresh();
werase(testwin);
wresize(testwin, LINES, COLS);
resize = 0;
}
box(testwin, 0, 0);
wnoutrefresh(testwin);
doupdate();
}
delwin(testwin);
endwin();
return EXIT_SUCCESS;
}