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

/* barChart, Chapter 3, pp. 137-138 */

#include 
#include "graphics.h"

#define WINDOW_WIDTH 600
#define WINDOW_HEIGHT 500
/* The amount of space to leave on each side of the chart */
#define MARGIN_WIDTH 0.05 * WINDOW_WIDTH
#define N_DATA 12

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

char * monthNames[N_DATA] = { "Jan", "Feb", "Mar", "Apr", "May", "Jun",
                              "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" };

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 */
void barChart (float * data) 
{
  wcPt2 dataPos[4], labelPos;
  Months m;
  float x, mWidth = (WINDOW_WIDTH - 2 * MARGIN_WIDTH) / N_DATA;
  int chartBottom = 0.1 * WINDOW_HEIGHT;
  int offset = 0.05 * WINDOW_HEIGHT; /* Space between data and labels */
  int labelLength = 24;    /* Assuming fixed-width 8-pixel characters */

  labelPos.y = chartBottom;
  for (m = Jan; m <= Dec; m++) {
    /* Find the center of this month's bar */
    x = MARGIN_WIDTH + m * mWidth + 0.5 * mWidth;

    /* Shift the label to the left by one-half its assumed length */
    labelPos.x = x - 0.5 * labelLength;
    pText (labelPos, monthNames[m]);

    /* Get the coordinates for this month's bar */
    dataPos[0].x = dataPos[3].x = x - 0.5 * labelLength;
    dataPos[1].x = dataPos[2].x = x + 0.5 * labelLength;
    dataPos[0].y = dataPos[1].y = chartBottom + offset;
    dataPos[2].y = dataPos[3].y = chartBottom + offset + data[m];
    pFillArea (4, dataPos);
  }
}
/* 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);
  barChart (data);   
  sleep (10);
  closeGraphics (windowID);
}