Computer Graphics | Program to Draw Graphics Objects using built-in C++ functions

By the end of this blog, you will be able to draw Pixels, Lines, Circles, Rectangles, and Ellipses. To start with Computer Graphics using C++, you must import the graphics library.

// Graphics Library for C++
#include <graphics.h>

After this. you can start the methods/functions available in this graphics library. Inside main() function Before using the functions for all those objects you have to initialize the Graphics mode on your computer. This is a necessary step to change your computer display mode to generate images.

        // gm is Graphics mode, a computer display mode to
    // generate image
    // DETECT is a macro defined in "graphics.h" header file
    int gd = DETECT, gm;

    // initgraph initializes the graphics system by loading a
    // graphics driver from disk, path can be empty
    initgraph(&gd, &gm, "");

This completes your setup for any of the methods listed in the graphics library. Let’s draw a pixel first.

        // putpixel(x,y,color): plots a pixel at location (x, y)
    // of specified color
    putpixel(50, 100, YELLOW);

This will create a new window on your screen on which a pixel a drawn. In addition to it, you can also print a string on the screen using,

// outtextxy(x,y,"string"):  displays the text or
    // string at a specified point (x, y) on the screen
    outtextxy(35, 55, "PIXEL");

For drawing a line along a string “LINE” above it, you’ll need,

        // line(x1, y1, x2, y2):  draws a line from a point(x1,y1) to point(x2,y2)
    line(120, 90, 170, 170);
    outtextxy(130, 55, "LINE");

For drawing a circle along a string “CIRCLE” above it, you’ll need,

        // circle(x,y,r): Draws a circle having center at x,y and having radius as r
    circle(240, 120, 40);
    outtextxy(215, 55, "CIRCLE");

For drawing a rectangle along a string “RECTANGLE” above it, you’ll need,

        // rectangle(left, top, right, bottom): Draws a rectangle
    // having coordinates of left top and right bottom corner
    rectangle(300, 90, 400, 140);
    outtextxy(310, 55, "RECTANGLE");

For drawing an ellipse along a string “ELLIPSE” above it, you’ll need,

        // ellipse(xCenter, yCenter, startAngle, endAngle, xRadius, yRadius):
    // Draws an ellipse for a given center, starting and ending angle
    // and horizontal and vertical radius.
    ellipse(500, 120, 0, 360, 70, 35);
    outtextxy(470, 55, "ELLIPSE");

After these function calls, you will need two additional function calls. First, one is fetch() and another one is a close graph()

        // getch() is a nonstandard function and is present in
    // conio.h header file
    // it pauses the Output Console until a key is pressed
    getch();

    // closegraph function closes the graphics
    // mode and deallocates all memory allocated
    // by graphics system .
    closegraph();

That’s all you need to draw these objects. The complete code is below,

#include <iostream>
// Graphics Library for C++
#include <graphics.h>
#include <conio.h>
#include <dos.h>
using namespace std;
int main()
{   
    int gd = DETECT, gm;
    initgraph(&gd, &gm, "");

    putpixel(50, 100, YELLOW);
    outtextxy(35, 55, "PIXEL");

    line(120, 90, 170, 170);
    outtextxy(130, 55, "LINE");

    circle(240, 120, 40);
    outtextxy(215, 55, "CIRCLE");

    rectangle(300, 90, 400, 140);
    outtextxy(310, 55, "RECTANGLE");

    ellipse(500, 120, 0, 360, 70, 35);
    outtextxy(470, 55, "ELLIPSE");
    getch();
    closegraph();

    return 0;
}

The output produced will be: