C Program to draw arc, pie-slice, and rectangle

Graphics in C - Draw arc, pie-slice, rectangle

C programming language is a very powerful computer language. It has all the functions you will need to create graphics. Here are a few more functions, which I shall demonstrate today. Before I explain something, please type this program in your editor:

#include<graphics.h>

void main()

{

        int gd=DETECT, gm, maxx, maxy;

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

        /* Finds maximum screen coordinates */

        maxx = getmaxx();

        maxy = getmaxy();

        /* Draws a circular arc */

        arc(maxx/5, maxy/5, 60, 250, 50);

        /* Draws a full circular arc (circle) */

        arc(maxx/3, maxy/5, 0, 360, 50);

        /* Draws a pie-slice */

        pieslice(maxx/2, maxy/5, 50, 270, 50);

        /* Draws a rectangle */

        rectangle(maxx*3/5, maxy/8, maxx*3/5+120, maxy/8+80);

        /* Sets the fill style and color */

        setfillstyle(HATCH_FILL, RED);

        /* Draws the pie-slice filled with above

           fill-style and color */

        pieslice(maxx/5, maxy/2, 60, 300, 50);

        arc(maxx/3, maxy/2, 0, 360, 50);

        /* floodfill() fills the arc with current

           fill-style and color */

        floodfill(maxx/3+1, maxy/2+1, WHITE);

        rectangle(maxx/2, maxy*2/5, maxx/2+120, maxy*2/5+80);

        /* floodfill() fills the rectangle with

           current fill-style and color */

        floodfill(maxx/2+1, maxy*2/5+1, WHITE);

        getch();

        closegraph();

        restorecrtmode();

}

Compile and execute this program. There are seven graphics in the output. In these, first graphic is an arc,  second is a fully drawn arc or say, circle. For these I have used function arc(). Function arc() draws a circular arc in the current drawing color.

Declaration:

void far arc(int x, int y, int stangle, int endangle, int radius);

Where ‘(x, y)’ is the center point of arc, ‘stangle’ is the start angle in degrees, ‘endangle’  is the end angle in degrees, and ‘radius’ is the radius of circular arc in pixels.

Syntax for calling this function is given below-

arc(x, y, stangle, endangle, radius);

Therefore, in the above program, the statement given below will draw a circular arc, whose center is ‘(maxx/5, maxy/5)’, start angle is ‘60’ degrees, end angle is ‘250’ degrees, and radius is ‘50’ pixels.

arc(maxx/5, maxy/5, 60, 250, 50);

If start angle is ‘0’, and end angle is ‘360’ degrees, the call to arc draws a complete circle. Hence, the statement given below will draw a complete circle.

arc(maxx/3, maxy/5, 0, 360, 50);

In the output, third graphic is a pie slice. For  drawing pie slice, I have used the function pieslice(). Function pieslice() draws a circular pie-slice in the current drawing color, then fills it using the current fill pattern and fill color.

Declaration:

void far pieslice(int x, int y, int stangle, int endangle, int radius);

Meaning of arguments is same as that of in the function arc().

Syntax for calling the function pieslice() is given below-

pieslice(x, y, stangle, endangle, radius);

Therefore, the statement given below will draw a circular pie slice with default fill pattern, and fill colour, since I have not set the fill pattern, and fill colour. On my computer default fill pattern is ‘solid fill’, and default fill colour is ‘white’.

pieslice(maxx/2, maxy/5, 50, 270, 50);

As I have mentioned earlier in the case of arc(), if the start angle is ‘0’, and end angle is ‘360’ degrees, the graphic drawn by the function pieslice() too will be a complete circle, filled  with current fill pattern, and current fill color. 

Fourth graphic is a rectangle. This has been drawn by the function rectangle(). Function rectangle() draws a rectangle in the current line style, thickness, and drawing colour.

Declaration:

void far rectangle(int left, int top, int right, int bottom);

Where ‘(left, top)’ is the upper left corner and ‘(right, bottom)’ is the lower right corner of the rectangle.

Syntax for calling the function rectangle() is given below-

rectangle(left, top, right, bottom);

Therefore, the statement given below draws a rectangle from ‘(maxx*3/5, maxy/8)’ to ‘(maxx*3/5+120, maxy/8+80)’ in the default color(white), default thickness(1 pixel), and default line style(solid).

rectangle(maxx*3/5, maxy/8, maxx*3/5+120, maxy/8+80);

How to change the colour, thickness, and line style, I’ll explain this later on.

Fifth graphic is a pie slice, filled with red pattern. These pattern and colour have been defined by the statement given below-

setfillstyle(HATCH_FILL, RED);

Function setfillstyle() has already been defined in my previous post.

Now, current fill pattern is ‘HATCH_FILL’, and current fill colour is ‘RED’.

Therefore, the statement given below draws a pie slice, filled with current fill pattern(HATCH_FILL), and current fill colour(RED).

pieslice(maxx/5, maxy/2, 60, 300, 50);

Sixth, and seventh graphics are a full drawn arc(complete circle), and a rectangle. These are filled with current fill pattern(HATCH_FILL), and current fill color(RED). These graphics are drawn by the functions arc() and rectangle(), which I have already explained. These graphics are not automatically filled by current fill pattern, and current fill color. To fill these graphics I have used the function floodfill(). This function fills a bounded region or an enclosed area.

Declaration:

void far floodfill((int x, int y, int border);

The area bounded by the color border is flooded with the current fill pattern, and current fill color. ‘(x, y)’ is a ‘seed point’. If the seed is within an enclosed area, the inside will be filled. If the seed is outside the enclosed area, the exterior will be filled. Argument ‘border’ is the color of the border of the enclosed area.

Function floodfill() does not work with the IBM-8514 driver.

Syntax for calling this function is given below-

floodfill(x, y, border_color);

I have used function floodfill() every time after function arc(), and function rectangle().

arc(maxx/3, maxy/2, 0, 360, 50);

floodfill(maxx/3+1, maxy/2+1, WHITE);

rectangle(maxx/2, maxy*2/5, maxx/2+120, maxy*2/5+80);

floodfill(maxx/2+1, maxy*2/5+1, WHITE);

Points ‘(maxx/3+1, maxy/2+1)’, and ‘( maxx/2+1, maxy*2/5+1)’ are the seed points, which are slightly inside the arc(complete circle), and the rectangle. Therefore, these are filled with current fill pattern, and current fill colour, which are red hatched pattern in our case. ‘WHITE’ is the colour of border of these graphics.

Now, the explanation of this simple program is complete. I’ll explain a few more functions in my next article. For the remaining functions and terms, please refer my previous posts.

OUTPUT:

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