Introduction to graphics programming in c

Date:27/03/2015

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Introduction to Graphics

Programming in

Team: Golden Girlzz

Contents

❏ Setting Up graphics using gcc

❏ Basic Idea About Graphics Programming in C

❏ Some functions in Graphics

❏ Working Example

❏ Computer Graphics is one of the most powerful and interesting aspect

of computers.

❏ There are many things we can do in graphics apart from drawing

figures of various shapes.

❏ All video games, animation, multimedia predominantly works using

computer graphics.

❏ There is a large number of functions in C which are used for putting pixel

on a graphic screen to form lines, shapes and patterns.

❏ The Default output mode of C language programs is “Text” mode.

❏ We have to switch to “Graphic” mode before drawing any graphical shape

like line, rectangle, circle etc.

❏ First of all, we must include the ”graphics.h” header file in our source

program

❏ GCC compiler doesn’t provides inbuilt facility to run graphics.h library.

❏ So you are not able to run graphics in C language

❏ To run "graphics.h" library in Ubuntu, following are some simple steps.

Graphics in C

Make sure that you have basic compilers installed. For this run the command:

Install few packages that required. Run the command:

Run “graphics.h” in Ubuntu

#1

sudo apt-get install build-essential

#2

sudo apt-get install libsdl-image1.2 libsdl-image1.2-dev guile-1.8 guile-

1.8-dev libsdl1.2debian libart-2.0-dev libaudiofile-dev libesd0-dev

libdirectfb-dev libdirectfb-extra libfreetype6-dev libxext-dev x11proto-

xext-dev libfreetype6 libaa1 libaa1-dev libslang2-dev libasound2

libasound2-dev

Now download libgraph

Copy libgraph-1.0.2.tar.gz to your home folder. Right click on it and select "Extract

Here".

Then run following commands one by one.

Now Ubuntu is ready to run graphics program. To do that add

#include<graphics.h> in your C program.

Here is a sample program to test it's working or not. sample.c

#3

cd libgraph-1.0.2

./configure

sudo make

sudo make install

sudo cp /usr/local/lib/libgraph.* /usr/li

#4

#include<graphics.h>

main() {

int gd=DETECT,gm;

initgraph(&gd,&gm,NULL);

closegraph();

}

❏ Run it with following command:

If you get following screen then graphics.h is working

gcc sample.c -o sample -lgraph

./sample

#5

Initializing Graphics Mode

❏ The initgraph function is used to switch the output from text mode to

graphics mode

❏ The initgraph function takes three arguments

❏ Syntax: –

intigraph(&graphics_driver,&graphics_mode,Path _to_driver);

❏ Example:

If you are working on Turbo C, use the path “c:\\tc\\bgi”

initgraph(&dr, &md, NULL );

Graphics Driver

Type

Initial Graphics

Mode

Directory Path of

Graphics Driver

Closing Graphics Mode

❏ Graphics mode must be closed at the end

❏ For that function closegraph() is used

❏ Syntax: –

closegraph();

Some Functions in

“graphics.h”

void line(int x1, int y1, int x2, int y2);

❏ Remarks

➔ line draws a line from (x1, y1) to (x2, y2) using the

current color

line()❏ line function is used to draw a line from a point(x1,y1) to

point(x2,y2)

❏ Syntax :-

void circle(int x, int y, int radius);

● (x , y) -> Center point of circle

● radius-> Radius of circle

circle()

❏ Circle function is used to draw a circle with center (x,y) and

third parameter specifies the radius of the circle.

❏ Syntax :-

void rectangle(int left, int top, int right, int

bottom);

rectangle()❏ Coordinates of left top and right bottom corner are required

to draw the rectangle.

❏ Syntax:-

void bar( left, top, right, bottom);

bar( )

❏ bar function draws a bar

❏ bar draws a filled-in, rectangular, two-dimensional bar.

❏ žSyntax:

void ellipse(int x, int y, int stangle, int endangle, int

xradius, int yradius);

ellipse()❏ Ellipse function is used to draw an ellipse, (x,y) are

coordinates of center of the ellipse, stangle is the

starting angle, end angle is the ending angle, and fifth

and sixth parameters specifies the X and Y radius of

the ellipse.

❏ Syntax :-

Note the Point:

In this, color can be represented

using the name of colors in

CAPITAL LETTER and also using

the numbers

Eg:

code 0 means BLACK

code 1 means BLUE

code 2 means GREEN

putpixel() and getpixel()

❏ getpixel() returns the color of pixel present at point(x, y)

❏ Syntax: –

❏ putpixel plots a pixel at a point(x, y) of specified color

❏ Syntax:-

int getpixel(int x, int y);

void putpixel(int x, int y, int color);

setbkcolor()

❏ setbkcolor function changes current background color e.g.

setbkcolor(YELLOW) changes the current background color to

YELLOW.

❏ Remember that default drawing color is WHITE and background color

is BLACK.

❏ Syntax :-

void setbkcolor(int color);

setcolor()

❏ setcolor() function changes current drawing color

❏ Syntax :-

❏ Example:

changes the current drawing color to YELLOW.

void setcolor(int color);

setcolor(YELLOW);

Text with Graphics

❏ There are functions in C language that draw text characters in

graphics mode.

❏ These functions can be used to mix text and graphics in the same

image.

❏ These functions also make it possible to change text font and very the

size of text.

outtext()

❏ displays a string in the viewport (graphics mode)

❏ Declaration:

❏ outtext display a text string, using the current justification settings and

the current font, direction, and size

❏ outtext outputs textstring at the current position (CP)

void outtext(char *textstring);

outtextxy()

❏ outtextxy displays a string at the specified location (graphics mode)

❏ Declaration:

❏ Remarks: outtextxy() display a text string, using the current

justification settings and the current font, direction, and size.(CP)

outtextxy() displays textstring in the viewport at the position (x, y)

void outtextxy(x, y, char *textstring);

Working

#include<graphics.h>

#include<stdio.h>

main() {

int gd = DETECT,gm,left=100,top=100,right=200,bottom=200;

int x=300,y=150,radius=50,color;

initgraph(&gd, &gm,NULL);

printf("Press any key to change the back color");

getch();

setbkcolor(2);

setcolor(RED);

outtext("Introduction to Graphics Programming....\n");

outtextxy(100,100,"Text at position x=100 and y=100");

color=getpixel(0,0);

printf("color of pixel at (0,0) = %d",color);

putpixel(25,25,YELLOW);

putpixel(25,26,YELLOW);

putpixel(25,27,YELLOW);

rectangle(left, top, right, bottom);

circle(x, y, radius);

bar(left+100,top+100,right+100,bottom+100);

line(left - 10, top + 150, left + 410, top + 150);

ellipse(x, y + 200, 0, 360, 100, 50);

outtextxy(left + 100, top + 325, "My First C Graphics Program");

getch();

closegraph();

return 0;

}

and the output is..

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