www.pudn.com > CG2Programs.rar > pieChart.c

/* pieChart, Chapter 3, p. 138-139 */

#include 
#include 
#include "graphics.h"

#define N_DATA 12
#define ROUND(a) ((int)(a+0.5))

typedef enum
{Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec} Months;

int readData (char * inFile, float * data)
{
  int fileError = FALSE;
  FILE * fp;
  Months month;

  if ((fp = fopen (inFile, "r")) == NULL)
    fileError = TRUE;
  else {
    for (month = Jan; month <= Dec; month++)  
      fscanf (fp, "%f", &data[month]);
    fclose (fp);
  }
  return (fileError);
}

/* EXAMPLE STARTS HERE */
#define TWO_PI 6.28

void pieChart (float * data)
{
  wcPt2 pts[2], center;
  float radius = WINDOW_HEIGHT / 4.0;
  float newSlice, total = 0.0, lastSlice = 0.0;
  Months month;

  center.x = WINDOW_WIDTH / 2;
  center.y = WINDOW_HEIGHT / 2;
  pCircle (center, radius);
  for (month = Jan; month <= Dec; month++) 
    total += data[month];
  pts[0].x = center.x; pts[0].y = center.y;
  for (month = Jan; month <= Dec; month++) {
    newSlice = TWO_PI * data[month] / total + lastSlice;
    pts[1].x = center.x + radius * cosf (newSlice); 
    pts[1].y = center.y + radius * sinf (newSlice); 
    pPolyline (2, pts);
    lastSlice = newSlice;
  }
}
/* EXAMPLE ENDS HERE */

void main (int argc, char ** argv)
{
  float data[N_DATA];
  int dataError = FALSE;
  long windowID;

  if (argc < 2) {
    fprintf (stderr, "Usage: %s dataFileName\n", argv[0]);
    exit ();
  }
  dataError = readData (argv[1], data);
  if (dataError) {
    fprintf (stderr, "%s error.  Couldn't read data file %s\n", argv[1]);
    exit ();
  }
  windowID = openGraphics (*argv, WINDOW_WIDTH, WINDOW_HEIGHT);
  setBackground (WHITE);
  setColor (BLACK);
  pieChart (data);
  sleep (10);
  closeGraphics (windowID);
}