How do I use getch from curses without clearing the screen?

Question

I'm learning to program in C and want to be able to type characters into the terminal while my code is running without pressing return. My program works, however when I call initscr(), the screen is cleared - even after calling filter(). The documentation for filter suggests it should disable clearing - however this is not the case for me.

#include <stdio.h>
#include <curses.h>
#include <term.h>

int main(void) {

    int ch;

    filter();
    initscr();
    cbreak();
    noecho();
    keypad(stdscr, TRUE);

    while((ch = getch()) != EOF);

    endwin();

    return 0;
}

Why does the above code still clearr the screen, and what could be done to fix it?

I'm using Debian Lenny (stable) and gnome-terminal if that helps.

Answer 1

Extending the answer by mike.dld, this works for me on MacOS X 10.6.6 (GCC 4.5.2) with the system curses library - without clearing the screen. I added the ability to record the characters typed (logged to a file "x"), and the ability to type CONTROL-D and stop the program rather than forcing the user to interrupt.

#include <stdio.h>
#include <curses.h>
#include <term.h>

#define CONTROL(x)  ((x) & 0x1F)

int main(void)
{
    FILE *fp = fopen("x", "w");
    if (fp == 0)
        return(-1);
    SCREEN *s = newterm(NULL, stdin, stdout);
    if (s == 0)
        return(-1);
    cbreak();
    noecho();
    keypad(stdscr, TRUE);

    int ch;
    while ((ch = getch()) != EOF && ch != CONTROL('d'))
        fprintf(fp, "%d\n", ch);

    endwin();

    return 0;
}