C++ Pixels In Console Window

Question

In C++ using Code::Blocks v10.05, how do I draw a single pixel on the console screen? Is this easy at all, or would it be easier to just draw a rectangle? How do I color it?

Answer 1

If you're willing to have the image look blocky, you could take advantage of the block characters from the console code page.

• █ = '\xDB' = U+2588 FULL BLOCK
• ▄ = '\xDC' = U+2584 LOWER HALF BLOCK
• ▀ = '\xDF' = U+2580 UPPER HALF BLOCK
• and space

By using the half-blocks in combination with colored text, you can turn an 80×25 console window into an 80×50 16-color display. (This was the approach used by the QBasic version of Nibbles.)

Then, you just need to convert your image to the 16-color palette and a reasonably small size.

Answer 2

To use in CodeBlocks I found this (you have to add a linker option -lgdi32): //Code Blocks: Project Build Options Linker settings Othoer linker options: add -lgdi32

I forgot: You have to put this before including windows.h :#define _WIN32_WINNT 0x0500

The whole cosine code again. Ready to compile

//Code Blocks: Project Build Options Linker settings Othoer linker options: add -lgdi32
#define _WIN32_WINNT 0x0500
#include "windows.h"
#include <iostream>
#include <cmath>
using namespace std;
#define PI 3.14
int main(){
    HWND myconsole = GetConsoleWindow();
    HDC mydc = GetDC(myconsole);
    int pixel =0;
    COLORREF COLOR= RGB(255,255,255);

    //Draw pixels
    for(double i = 0; i < PI * 4; i += 0.05)
    {
        SetPixel(mydc,pixel,(int)(50+25*cos(i)),COLOR);
        pixel+=1;
    }

    ReleaseDC(myconsole, mydc);
    cin.ignore();
    return 0;
}

Answer 3

windows.h provides a function SetPixel() to print a pixel at specified location of a window. The general form of the function is

SetPixel(HDC hdc, int x, int y, COLORREF& color);

where, x and y are coordinates of pixel to be display and color is the color of pixel.

Important: to print the pixel in your machine with Code::blocks IDE, add a link library libgdi32.a (it is usually inside MinGW\lib ) in linker setting.

Answer 4

I have drawn the straight line using windows.h in code::blocks. I can't explain it in details, but I can provide you a code and procedure to compile it in code::blocks.

1. go to setting menu and select compiler and debugger.
2. Click on linker tab and add a link library libgdi32.a which is at C:\Program Files\CodeBlocks\MinGW\lib directory.

Now compile this program

#include <windows.h>

#include <cmath>

#define ROUND(a) ((int) (a + 0.5))

/* set window handle */

static HWND sHwnd;

static COLORREF redColor=RGB(255,0,0);

static COLORREF blueColor=RGB(0,0,255);

static COLORREF greenColor=RGB(0,255,0);


void SetWindowHandle(HWND hwnd){

sHwnd=hwnd;

}

/* SetPixel */

void setPixel(int x,int y,COLORREF& color=redColor){

if(sHwnd==NULL){

    MessageBox(NULL,"sHwnd was not initialized !","Error",MB_OK|MB_ICONERROR);

    exit(0);

}

HDC hdc=GetDC(sHwnd);

SetPixel(hdc,x,y,color);

ReleaseDC(sHwnd,hdc);

return;

// NEVERREACH //

}


void drawLineDDA(int xa, int ya, int xb, int yb){

   int dx = xb - xa, dy = yb - ya, steps, k;

   float xIncrement, yIncrement, x = xa, y = ya;

   if(abs(dx) > abs(dy)) steps = abs(dx);

   else steps = abs(dy);

   xIncrement = dx / (float) steps;

   yIncrement = dy / (float) steps;

   setPixel(ROUND(x), ROUND(y));

   for(int k = 0; k < steps; k++){

    x += xIncrement;

    y += yIncrement;

    setPixel(x, y);

 }

}

/* Window Procedure WndProc */

LRESULT CALLBACK WndProc(HWND hwnd,UINT message,WPARAM wParam,LPARAM lParam){

 switch(message){

    case WM_PAINT:

        SetWindowHandle(hwnd);

        drawLineDDA(10, 20, 250, 300);

        break;

    case WM_CLOSE: // FAIL THROUGH to call DefWindowProc

        break;

    case WM_DESTROY:

        PostQuitMessage(0);

        return 0;

    default:

    break; // FAIL to call DefWindowProc //

  }

 return DefWindowProc(hwnd,message,wParam,lParam);

}

int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPSTR lpCmdLine,int      iCmdShow){

static TCHAR szAppName[] = TEXT("Straight Line");

WNDCLASS wndclass;

wndclass.style         = CS_HREDRAW|CS_VREDRAW ;

wndclass.lpfnWndProc   = WndProc ;

wndclass.cbClsExtra    = 0 ;

wndclass.cbWndExtra    = 0 ;

wndclass.hInstance     = hInstance ;

wndclass.hIcon         = LoadIcon (NULL, IDI_APPLICATION) ;

wndclass.hCursor       = LoadCursor (NULL, IDC_ARROW) ;

wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;

wndclass.lpszMenuName  = NULL ;

wndclass.lpszClassName = szAppName ;

// Register the window //

if(!RegisterClass(&wndclass)){

    MessageBox(NULL,"Registering the class failled","Error",MB_OK|MB_ICONERROR);

    exit(0);

}

// CreateWindow //

HWND hwnd=CreateWindow(szAppName,"DDA - Programming Techniques",

            WS_OVERLAPPEDWINDOW,

             CW_USEDEFAULT,

             CW_USEDEFAULT,

             CW_USEDEFAULT,

             CW_USEDEFAULT,

             NULL,

             NULL,

             hInstance,

             NULL);

if(!hwnd){

    MessageBox(NULL,"Window Creation Failed!","Error",MB_OK);

    exit(0);

  }

  // ShowWindow and UpdateWindow //

  ShowWindow(hwnd,iCmdShow);

 UpdateWindow(hwnd);

 // Message Loop //

 MSG msg;

 while(GetMessage(&msg,NULL,0,0)){

    TranslateMessage(&msg);

    DispatchMessage(&msg);

 }

  /* return no error to the operating system */

  return 0;

}

In this program I have used DDA line drawing algorithm. Pixel drawing tasks is done by setPixel(ROUND(x), ROUND(y)) function. This is windows programing which you can learn details here

Answer 5

Console is a text device, so in general you don't write to individual pixels. You can create a special font and select it as a font for console, but it will be monochromatic. There are libraries which simplify writing console UI (e.g. Curses), but I believe that you also have more gamelike functionality in mind besides just showing a sprite.

if you want to write a game, I suggest taking a look at some of the graphics/game frameworks/libs, e.g. SDL

Answer 6

It depends on your OS. I suppose you are programming in a Windows platform, therefore you can use SetPixel but you have to use "windows.h" to get a console handle, so here an example for drawing the cos() function:

#include<windows.h>
#include<iostream>
#include <cmath>

using namespace std;

#define PI 3.14

int main() 
{
    //Get a console handle
    HWND myconsole = GetConsoleWindow();
    //Get a handle to device context
    HDC mydc = GetDC(myconsole);

    int pixel =0;

    //Choose any color
    COLORREF COLOR= RGB(255,255,255); 

    //Draw pixels
    for(double i = 0; i < PI * 4; i += 0.05)
    {
        SetPixel(mydc,pixel,(int)(50+25*cos(i)),COLOR);
        pixel+=1;
    }

    ReleaseDC(myconsole, mydc);
    cin.ignore();
    return 0;
}

You can also use some others libraries like: conio.h allegro.h sdl, etc.