C Program to explain different line-styles

Graphics in C - Predefined and User-defined Line Styles

In the previous posts, we have drawn only solid lines. Sometimes we may want to draw lines in other styles. In C programming language, different types of lines can be drawn. Besides solid lines, you can draw dotted lines, center lines, dashed lines, and user-defined lines. I have described these line styles in this post. Please type this program in your editor.

#include<graphics.h>

void main()

{

     /* Declares and initializes array of pointers

        to string */

    char *style[5]={

                        "SOLID_LINE style(value = 0)",

                        "DOTTED_LINE style(value = 1)",

                        "CENTER_LINE style(value = 2)",

                        "DASHED_LINE style(value = 3)",

                        "USERBIT_LINE style(value = 4)"

                      };

    int i, x1=100, y1=125, x2=250, y2=100;

    int upattern = 0xAA; /* bit pattern: 1010 1010 */

    int gd = DETECT, gm;

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

    /* Displays the message */

    outtextxy(200, 50, "Line Styles");

    for(i=0; i<=4; i++)

    {

          if(i==4)

          {

                 setlinestyle(i, upattern, 1);

          }

          else

          {

                 setlinestyle(i, 0, 1);

          }

          line(x1, y1, x1+100, y1);

          rectangle(x2, y2, x2+100, y2+50);

          outtextxy(x2+150, y2+25, style[i]);

          y1+=60;

          y2+=60;

    }

    getch();

    closegraph();

    restorecrtmode();

}

Compile and execute this program. In the output, you will see one set of five lines and another set of five rectangles in different line styles. For different line styles, I have used the function setlinestyle(). Function setlinestyle() sets the current line style, line pattern, and line width. Line pattern is the user-defined pattern. This function sets the style for all lines drawn by functions line(), rectangle(), drawpoly(), etc.

Declaration:

void far setlinestyle(int linestyle, unsigned upattern, int thickness);

Syntax for calling this function is given below-

setlinestyle(linestyle, upattern, thickness);

Where’ linestyle’ is either system-defined or user-defined, depending on the value of ‘linestyle’. Its values can be an integer from 0 to 4. You can give the name of constants instead of integer values. The names of constants and their corresponding integer values are given below-

Name of constant               Integer value

SOLID_LINE                                   0

DOTTED_LINE                               1

CENTER_LINE                               2

DASHED_LINE                               3

USERBIT_LINE                              4

Value ‘4’ is for user-defined line style. ‘upattern’ is user-defined pattern, which is given, when you give value ‘4’ for line-style, otherwise it is set to ‘0’.  ‘thickness’ is the width of line, and its value can be given from 1 to 3. If you give the invalid values to this function, the current line style remains unchanged.

In the above program, I have used a ‘for’ loop, which iterates through loop variable i = 0 to 4.  In the ‘for’ loop, an ‘if’ construct selects a ‘setlinestyle’ statement on the basis of the value of ‘i’. If the value of ‘i’ is 4, then line-style is USERBIT_LINE(means user-defined line-style), the statement setlinestyle(i, upattern, 1);  will be executed. ‘upattern’ has been given the hexadecimal value ‘0xAA’ (bit pattern 1010 1010), and thickness of line is ‘1’. If the value of  ‘i’ is from 0 to 3, statement setlinestyle(i, 0, 1); will be executed. This time, value of ‘upattern’ has been set to ‘0’, and ‘thickness’ of line is again ‘1’. On the basis of settings of function ‘setlinestyle(), lines and rectangles have been drawn. Function outtextxy() has been used to describe the line-styles.

Thus, this simple program describes the use of function setlinestyle(). For the remaining functions and other things, please refer my previous posts.

OUTPUT:

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