I20 Answer

#include <stdlib.h>
#include <stdio.h>
#include "basicImage.c"

int main ( int argc, char* argv[] )
{
  image img ;
  int r, c;
  int nrows, ncols, below, above, radius ;
  int rc, cc; /* coordinates of center */

  if ( argc != 7)
  {
    printf("diagImage fileName nrows ncols below above radius\n");
    return EXIT_SUCCESS;
  }

  nrows = atoi( argv[2] );
  ncols = atoi( argv[3] );
  below = atoi( argv[4] );
  above = atoi( argv[5] );
  radius= atoi( argv[6] );

  if ( newImage( &img, nrows, ncols ) == NULL )
  {
    printf(">>error<< can't allocate memory\n");
    return;
  }

  /* calculate the coordinates of the center */
  rc = nrows/2;
  cc = ncols/2;

  /* First create the diagonally split two level image */
  for ( r = 0; r < img.nrows; r++ )
    for ( c = 0; c < img.ncols; c++ )
      if ( r > c )
        setPixel( img, r, c, below );
      else
        setPixel( img, r, c, above );

  /* start the random number generator */
  srand( time(NULL) );

  /* Next randomly select 25% of the pixels */
  for ( j=0; j < (nrows*ncols)/4; j++ )
  {
    r = rand()%nrows;
    c = rand()%ncols;

    /* if the selected pixel is inside of the circle */
    /* reverse its gray level */
    if ( (r-rc)*(r-rc)+(c-cc)*(c-cc) < radius*radius )
      if ( r > c )
        setPixel( img, r, c, above );
      else
        setPixel( img, r, c, below );
  }

  writePGMImage( img, argv[1]);
  freeImage( &img );
}