etch.c

#include <curses.h>
#include <signal.h>

#define RED_RED         9
#define WHITE_BLACK     10
#define WHITE_WHITE     11

void done();
void rszf();
void drwc();
void drwf();

const char* TITLE   = "Etch-a-Sketch";
const char* MOVE    = "Use the Arrow Keys to Move.";
const char* KEYS    = "Press 's' to Shake. Press 'q' to Quit.";

int x, y, mx, my, t, r, b, l;

void done()
{
    endwin();
    exit (0);
}

void rszf()
{
    endwin();
    curs_set(0);
    refresh();
    drwf();
    drwc();
}

void drwc()
{
    if (x > r) x = r;
    if (x < l) x = l;
    if (y > b) y = b;
    if (y < t) y = t;

    color_set(WHITE_WHITE, NULL);
    mvaddch(y, x, '.');

    refresh();
}

void drwf()
{
    mx = getmaxx(stdscr);
    my = getmaxy(stdscr);

    t = 1;
    r = mx - 2;
    b = my - 2;
    l = 1;

    clear();

    color_set(RED_RED, NULL);
    box(stdscr, 0, 0);

    if (r - l >= strlen(TITLE) && b - t > 2)
    {
        color_set(RED_RED, NULL);
        mvhline(t + 1, l, 0, r);

        attron(A_BOLD);
        color_set(WHITE_BLACK, NULL);
        mvaddstr(t, (r - l - strlen(TITLE)) / 2, TITLE);
        attroff(A_BOLD);

        t += 2;
    }

    if (r - l > 14 && b - t > 8)
    {
        color_set(RED_RED, NULL);
        mvhline(b - 6, l, 0, r);

        color_set(WHITE_WHITE, NULL);
        mvaddstr(b - 4, l + 2, "....");
        mvaddstr(b - 3, l + 1, "......");
        mvaddstr(b - 2, l + 1, "......");
        mvaddstr(b - 1, l + 2, "....");

        mvaddstr(b - 4, r - 6, "....");
        mvaddstr(b - 3, r - 7, "......");
        mvaddstr(b - 2, r - 7, "......");
        mvaddstr(b - 1, r - 6, "....");

        if (r - l > strlen(MOVE) + 16 && r - l > strlen(KEYS) + 16)
        {
            color_set(WHITE_BLACK, NULL);
            mvaddstr(b - 3, (r - l - strlen(MOVE) + 2) / 2, MOVE);
            mvaddstr(b - 2, (r - l - strlen(KEYS) + 2) / 2, KEYS);
        }

        b -= 7;
    }

    touchwin(stdscr);
    refresh();
}

int main()
{
    signal(SIGINT, done);
    signal(SIGWINCH, rszf);

    initscr();
    keypad(stdscr, TRUE);
    nonl();
    cbreak();
    noecho();
    curs_set(0);

    if (has_colors())
    {
        start_color();

        init_pair(RED_RED,      COLOR_RED,     COLOR_RED);
        init_pair(WHITE_BLACK,  COLOR_WHITE,   COLOR_BLACK);
        init_pair(WHITE_WHITE,  COLOR_WHITE,   COLOR_WHITE);
    }

    drwf();

    x = l;
    y = t;

    drwc();

    for (;;)
    {
        switch (getch())
        {
            case KEY_UP:      y--;        break;
            case KEY_RIGHT:   x++;        break;
            case KEY_DOWN:    y++;        break;
            case KEY_LEFT:    x--;        break;

            case 's':         drwf();     break;
            case 'q':         done();     break;
        }

        drwc();
    }

    return 1;
}

This is oldest piece of code that I've written that I still have. I wrote it when I was 13!