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);
		}
	  }