cgraphics: C Program to create the user-defined fill-pattern

Graphics in C - Demonstration of User-defined fill-pattern

In C programming language we can give fill-patterns by two methods. One is standard system defined, and other is user-defined. I have described function setfillstyle() previously. Function setfillstyle() fills the standard predefined fill patterns. If you want to give user-defined fill patterns, you can use function setfillpattern(). Here is a simple program given below. Please type this program in your editor.

#include<graphics.h>

void main()

{

/* Declares and initializes array with

user-defined bit-pattern */

char patt[] = {0x0F, 0xF0, 0x0F, 0xF0, 0x0F, 0xF0, 0x0F, 0xF0};

int gd = DETECT, gm;

initgraph(&gd, &gm, "c:\\tc\\bgi");

/* Sets the user-defined fill-pattern and color */

setfillpattern(patt, RED);

/* Draws a rectangle */

rectangle(100, 100, 400, 400);

/* Fills the rectangle with user-defined

fill-pattern and color */

floodfill(101, 101, WHITE);

getch();

closegraph();

restorecrtmode();

}

Compile and execute this program. The output will be a rectangle filled with nice checker red pattern. To create user-defined pattern, I have used the function setfillpattern().

Declaration:

void far setfillpattern(char far *upattern, int color);

Where ‘upattern’ is a pointer to a sequence of ‘8’ bytes, each byte consists of 8 pixels. You can store this 8 byte sequence of pattern in an array. In every byte, if a bit is set to ‘1’, a pixel will be drawn, and if a bit is set to ‘0’, pixel will not be drawn. ‘colour’ parameter specifies the colour of user-defined pattern.

Syntax for calling this function is given below-

setfillpattern(upattern, color);

In the given program, an array ‘patt[8]’ has been declared and initialized with 2 hexadecimal numbers ‘0x0F’ and ‘0xF0’ in alternating fashion (0x0Fà0000 1111 and 0xF0à 1111 0000). Number of array elements is 8, which denotes to 8 bytes. Therefore, wherever a bit is ‘1’, a pixel will be drawn in given colour, which is ‘RED’ in the given program. Therefore, a pattern of bits will be like this-

0000 1111

1111 0000

0000 1111

1111 0000

0000 1111

1111 0000

0000 1111

1111 0000

The statement given below will set a checker like pattern in red color. ‘patt’ is the address of array ‘patt[8]’.

setfillpattern(patt, RED);

Since, function rectangle() is not automatically filled with given fill pattern, I have used the function floodfill().

floodfill(101, 101, WHITE);