Simple C++ Animation – Ultimate Color Randomness

In yesterday’s post, the random rectangles are printed using console only without the help of any graphics. The basic type of each element/pixel in the console (code page 437) is defined in the following C/C++ structure:

typedef struct {
    unsigned char elem;
    unsigned char color;
} SCREENELEMENT;

Therefore, we can easily change the color and character of each pixel, to illustrate the ultimate color showing, we can use extended ASCII 219 to print out a solid square to the console.

const unsigned char BLACK = 219;

Now, the core statements are just a few lines:

    for (;;) {
        for (int i = 0; i < height; i ++) {
            for (int j = 0; j < width; j ++) {
                s[i][j].color = rand() % 16;
            }
        }
        printScreen(width, height, s);
    }

It gives the following output, you can use it as a screen saver (to rename the file extension from *.exe to *.scr)

The pre-compiled C++ animation application (g++ compiler/windows) can be downloaded [here ].

The complete C++ source code is:

/* http://HelloACM.com */
#include <iostream>
#include <stdio.h>
#include <windows.h>
#include <unistd.h> // usleep
#include <time.h> // for time

using namespace std;

const unsigned char BLACK = 219;

typedef struct {
    unsigned char elem;
    unsigned char color;
} SCREENELEMENT;

BOOL gotoxy(const WORD x, const WORD y) {
    COORD xy;
    xy.X = x;
    xy.Y = y;
    return SetConsoleCursorPosition(GetStdHandle(STD_OUTPUT_HANDLE), xy);
}

inline // update the screen
void printScreen(int width, int height, SCREENELEMENT **screen) {
    gotoxy(1, 1); // top-left corner
    for (int i = 0; i < height; i ++) {
        for (int j = 0; j < width; j ++) {             
                SCREENELEMENT *cur = &screen[i][j];             
                SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), cur->color);
                printf("%c", cur->elem); // may be faster than cout
        }
    }
}

inline // initialize the screen with pixel se
void initScreen(int width, int height, SCREENELEMENT **screen, SCREENELEMENT se) {
    for (int i = 0; i < height; i ++) {
        for (int j = 0; j < width; j ++) {
            screen[i][j] = se;
        }
    }
}

int main() {
    SetConsoleOutputCP(437);
    CONSOLE_SCREEN_BUFFER_INFO csbi;
    int ret;
    /* get the width of the console */
    ret = GetConsoleScreenBufferInfo(GetStdHandle(STD_OUTPUT_HANDLE), &csbi);
    int width = 80;
    if (ret) {
        width = csbi.dwSize.X;
    }
    int height = csbi.srWindow.Bottom - csbi.srWindow.Top;
    SCREENELEMENT **s = new SCREENELEMENT*[height];
    for (int i = 0; i < height; i ++) {
        s[i] = new SCREENELEMENT[width];
    }
    SCREENELEMENT se;
    se.elem = BLACK;
    se.color = 0;
    initScreen(width, height, s, se);
    srand(time(NULL));
    for (;;) {
        for (int i = 0; i < height; i ++) {
            for (int j = 0; j < width; j ++) {
                s[i][j].color = rand() % 16;
            }
        }
        printScreen(width, height, s);
    }
    /* clean up */
    for (int i = 0; i < height; i ++) {
        delete[] s[i];
    }
    delete[] s; 
    return 0; /* use Ctrl+C, never returns */
}

–EOF (The Ultimate Computing & Technology Blog) —