#include <math.h>
#include <grass/raster.h>
#include <grass/display.h>
#include <grass/gis.h>

char percent[] = "%";

int 
draw_slice (
    struct Colors *colors,
    int fill_flag,
    DCELL fill_color1,
    DCELL fill_color2,
    int txt_color,
    double cx,
    double cy,
    double r,          /* in normalized coords. */
    double a1,
    double a2             /* in degrees */
)
{
int    tt,tb,tr,tl;
int    height, width;
int    yoffset,
       xoffset;
int    x[1000], y[1000];
int    lx,ly;
int    i=1;
char   txt[512];
       double arc,
       arc_incr=0.01;
DCELL fill_color;

D_get_screen_window(&tt, &tb, &tl, &tr);

height = tb-tt;
width = tr-tl;
yoffset = tb;
xoffset = tl;

while (a2/arc_incr > 998)
   arc_incr *= 2;

x[0] = (int)((double)xoffset+cx*(double)width);
y[0] = (int)((double)yoffset-cy*(double)height);

arc=a1;
if(fill_flag && fill_color1 != fill_color2)
{
   i = 1;
   while ( arc<=(a1+a2) )
   {
      fill_color = fill_color1 + (arc-a1) * 
			 (fill_color2-fill_color1)/ a2;
      x[i] = x[0] + r*(width)*cos(arc/57.296);
      y[i] = y[0] - r*(height)*sin(arc/57.296);
      if(i==2)
      {
         D_d_color(fill_color, colors);
         R_polygon_abs(x+i-2,y+i-2,3);
	 x[i-1] = x[i];
	 y[i-1] = y[i];
      }
      else
	 i++;
      arc = arc+arc_incr;
   }
}
else
{
   i = 1;
   while ( arc<=(a1+a2) )
   {
      x[i] = x[0] + r*(width)*cos(arc/57.296);
      y[i] = y[0] - r*(height)*sin(arc/57.296);
      i++;
      arc = arc+arc_incr;
   }

   if (!fill_flag)
   {
      R_standard_color(txt_color);
      R_polyline_abs(x,y,i);
   }
   else 
   {
      D_d_color(fill_color1, colors);
      R_polygon_abs(x,y,i);
   }
}

if (a2>15.0) 
{
   /* draw a label */
   arc = a1+a2/2;
   sprintf(txt,"%2.0f%s",(double)(a2/(double)360.0)*(double)100.0,percent);
   R_get_text_box(txt,&tt,&tb,&tl,&tr);
   lx  = x[0] + (r+0.03)*(width)*cos(arc/57.296)-(tr-tl)/2;      
   ly  = y[0] - (r+0.03)*(height)*sin(arc/57.296)+(tb-tt)/2;      
   R_move_abs(lx,ly);
   R_standard_color(txt_color);
   R_text(txt);
}

	return 0;
}

int draw_slice_unfilled (
    struct Colors *colors,
    int tc,
    double cx,
    double cy, /* circle center, in normalized coords. */
    double r,      /* circle radius, in normalized units */
    double a1,     /* arc start position, in degrees */
    double a2     /* arc size, in degrees */
)
{
	draw_slice(colors,0,0.,0.,tc,cx,cy,r,a1,a2);

	return 0;
}


int draw_slice_filled (
    struct Colors *colors,
    DCELL fc,     /* fill color */
    int tc,     /* text color */
    double cx,
    double cy, /* circle center, in normalized coords. */
    double r,      /* circle radius, in normalized units */
    double a1,     /* arc start position, in degrees */
    double a2     /* arc size, in degrees */
)
{
	draw_slice(colors, 1,fc,fc,tc,cx,cy,r,a1,a2);

	return 0;
}