Program to fill different types of geometric shapes using Boundary Fill Algorithm

 # include <iostream.h>
 # include <graphics.h>
 # include    <conio.h>
 # include     <math.h>


 void show_screen( );

 void Boundary_fill(const int,const int,const int,const int);

 void Circle(const int,const int,const int);
 void Triangle(const int,const int,const int,const int,const int,const int);
 void Rectangle(const int,const int,const int,const int);
 void Polygon(const int,const int []);
 void Line(const int,const int,const int,const int);


 int main( )
    {
       int driver=VGA;
       int mode=VGAHI;

       initgraph(&driver,&mode,\"..\\\\Bgi\");

       show_screen( );

       setcolor(15);
     Circle(175,175,40);

     Boundary_fill(175,175,10,15);

       setcolor(15);
       settextstyle(0,0,1);
     outtextxy(150,225,\"Circle\");

       setcolor(15);
     Rectangle(375,145,475,205);

     Boundary_fill(400,175,9,15);

       setcolor(15);
       settextstyle(0,0,1);
     outtextxy(390,215,\"Rectangle\");

       setcolor(15);
     Triangle(135,360,215,360,175,290);

     Boundary_fill(175,325,8,15);

       setcolor(15);
       settextstyle(0,0,1);
     outtextxy(145,370,\"Triangle\");

       int polygon_points[14]={ 365,325, 400,290, 450,290, 485,325,
                        450,360, 400,360, 365,325 };

       setcolor(15);
     Polygon(7,polygon_points);

     Boundary_fill(425,325,12,15);

       setcolor(15);
       settextstyle(0,0,1);
     outtextxy(395,370,\"Polygon\");

       getch( );
       return 0;
    }


 //--------------------------  Boundary_fill( )  -------------------------//


 void Boundary_fill(const int x,const int y,
                 const int fill_color,const int boundary_color)
    {
       if(getpixel(x,y)!=boundary_color && getpixel(x,y)!=fill_color)
      {
         putpixel(x,y,fill_color);

         Boundary_fill((x+1),y,fill_color,boundary_color);
         Boundary_fill((x-1),y,fill_color,boundary_color);
         Boundary_fill(x,(y+1),fill_color,boundary_color);
         Boundary_fill(x,(y-1),fill_color,boundary_color);
      }
    }


 //------------------------------  Circle( )  ----------------------------//


 void Circle(const int h,const int k,const int r)
    {
       int color=getcolor( );

       int x=0;
       int y=r;
       int p=(1-r);

       do
      {
         putpixel((h+x),(k+y),color);
         putpixel((h+y),(k+x),color);
         putpixel((h+y),(k-x),color);
         putpixel((h+x),(k-y),color);
         putpixel((h-x),(k-y),color);
         putpixel((h-y),(k-x),color);
         putpixel((h-y),(k+x),color);
         putpixel((h-x),(k+y),color);

         x++;

         if(p<0)
        p+=((2*x)+1);

         else
        {
           y--;
           p+=((2*(x-y))+1);
        }
      }
       while(x<=y);
    }


 //----------------------------  Triangle( )  ----------------------------//


 void Triangle(const int x_1,const int y_1,const int x_2,const int y_2,
                        const int x_3,const int y_3)
    {
       Line(x_1,y_1,x_2,y_2);
       Line(x_2,y_2,x_3,y_3);
       Line(x_3,y_3,x_1,y_1);
    }


 //---------------------------  Rectangle( )  ----------------------------//


 void Rectangle(const int x_1,const int y_1,const int x_2,const int y_2)
    {
       Line(x_1,y_1,x_2,y_1);
       Line(x_2,y_1,x_2,y_2);
       Line(x_2,y_2,x_1,y_2);
       Line(x_1,y_2,x_1,y_1);
    }


 //-----------------------------  Polygon( )  ----------------------------//


 void Polygon(const int n,const int coordinates[])
    {
       if(n>=2)
      {
         Line(coordinates[0],coordinates[1],
                         coordinates[2],coordinates[3]);

         for(int count=1;count<(n-1);count++)
        Line(coordinates[(count*2)],coordinates[((count*2)+1)],
                        coordinates[((count+1)*2)],
                        coordinates[(((count+1)*2)+1)]);
      }
    }


 //-------------------------------  Line( )  -----------------------------//


 void Line(const int x_1,const int y_1,const int x_2,const int y_2)
    {
       int color=getcolor( );

       int x1=x_1;
       int y1=y_1;

       int x2=x_2;
       int y2=y_2;

       if(x_1>x_2)
      {
         x1=x_2;
         y1=y_2;

         x2=x_1;
         y2=y_1;
      }

       int dx=abs(x2-x1);
       int dy=abs(y2-y1);
       int inc_dec=((y2>=y1)?1:-1);

       if(dx>dy)
      {
         int two_dy=(2*dy);
         int two_dy_dx=(2*(dy-dx));
         int p=((2*dy)-dx);

         int x=x1;
         int y=y1;

         putpixel(x,y,color);

         while(x<x2)
        {
           x++;

           if(p<0)
              p+=two_dy;

           else
              {
             y+=inc_dec;
             p+=two_dy_dx;
              }

           putpixel(x,y,color);
        }
      }

       else
      {
         int two_dx=(2*dx);
         int two_dx_dy=(2*(dx-dy));
         int p=((2*dx)-dy);

         int x=x1;
         int y=y1;

         putpixel(x,y,color);

         while(y!=y2)
        {
           y+=inc_dec;

           if(p<0)
              p+=two_dx;

           else
              {
             x++;
             p+=two_dx_dy;
              }

           putpixel(x,y,color);
        }
      }
    }


 //--------------------------  show_screen( )  ---------------------------//


 void show_screen( )
    {
       setfillstyle(1,1);
     bar(220,26,420,38);

       settextstyle(0,0,1);
     setcolor(15);
       outtextxy(5,5,\"******************************************************************************\");
       outtextxy(5,17,\"*-**************************************************************************-*\");
       outtextxy(5,29,\"*-------------------------                           ------------------------*\");
       outtextxy(5,41,\"*-**************************************************************************-*\");
       outtextxy(5,53,\"*-**************************************************************************-*\");

     setcolor(11);
       outtextxy(228,29,\"Boundary Fill Algorithm\");

     setcolor(15);

       for(int count=0;count<=30;count++)
          outtextxy(5,(65+(count*12)),\"*-*                                                                        *-*\");

       outtextxy(5,438,\"*-**************************************************************************-*\");
       outtextxy(5,450,\"*-------------------------                          -------------------------*\");
       outtextxy(5,462,\"******************************************************************************\");

     setcolor(12);
       outtextxy(229,450,\"Press any Key to exit.\");
    }