#include "hdf.h"

#define  FILE_NAME       "General_RImages.hdf"
#define  RI_ATTR_NAME    "Image Attribute 2"

int main( ) 
{
   /************************* Variable declaration **************************/

   intn   status;          /* status for functions returning an intn */
   int32  gr_id, ri_id, file_id,
          f_att_index,     /* index of file attributes */
          ri_att_index,    /* index of raster image attributes */
          data_type,       /* image data type */
          n_values,        /* number of values in an attribute */
          value_index,     /* index of values in an attribute */
          n_rimages,       /* number of raster images in the file */
          n_file_attrs;    /* number of file attributes */
   char   attr_name[H4_MAX_GR_NAME];  /* buffer to hold the attribute name     */
   VOIDP  data_buf;                /* buffer to hold the attribute values   */
   int16 *int_ptr;      /* int16 pointer to point to a void data buffer     */
   char8 *char_ptr;     /* char8 pointer to point to a void data buffer     */

   /********************** End of variable declaration **********************/

   /*
   * Open the HDF file.
   */
   file_id = Hopen (FILE_NAME, DFACC_READ, 0);

   /*
   * Initialize the GR interface.
   */
   gr_id = GRstart (file_id);

   /*
   * Determine the number of attributes in the file.
   */
   status = GRfileinfo (gr_id, &n_rimages, &n_file_attrs);
   if (status != FAIL && n_file_attrs > 0)
   {
      for (f_att_index = 0; f_att_index < n_file_attrs; f_att_index++)
      {
         /*
         * Get information about the current file attribute.
         */
         status = GRattrinfo (gr_id, f_att_index, attr_name, &data_type, 
                              &n_values);

         /*
         * Allocate a buffer to hold the file attribute data.  In this example,
         * knowledge about the data type is assumed to be available from 
         * the previous example for simplicity.  In reality, the size
         * of the type must be determined based on the machine where the 
         * program resides.
         */
         if (data_type == DFNT_CHAR8)
         {
            data_buf = malloc (n_values * sizeof (char8));
            if (data_buf == NULL)
            {
               printf ("Unable to allocate space for attribute data.\n");
               exit (1);
            }
         }
         else
         {
            printf ("Unable to determine data type to allocate data buffer.\n");
            exit (1);
         }

         /*
         * Read and display the attribute values.
         */
         status = GRgetattr (gr_id, f_att_index, (VOIDP)data_buf);

         char_ptr = (char8 *) data_buf;
         printf ("Attribute %s: ", attr_name);
         for (value_index = 0; value_index < n_values; value_index++)
            printf ("%c", char_ptr[value_index]);
         printf ("\n");

         /*
         * Free the space allocated for the data buffer.
         */

         free (data_buf);

      } /* for */
   } /* if */

   /*
   * Select the second image in the file.
   */
   ri_id = GRselect (gr_id, 1);

   /*
   * Find the image attribute named RI_ATTR_NAME.
   */
   ri_att_index = GRfindattr (ri_id, RI_ATTR_NAME);

   /*
   * Get information about the attribute.
   */
   status = GRattrinfo (ri_id, ri_att_index, attr_name, &data_type, &n_values);

   /*
   * Allocate a buffer to hold the file attribute data.  As mentioned above,
   * knowledge about the data type is assumed to be available from
   * the previous example for simplicity.  In reality, the size of the 
   * type must be determined based on the machine where the program resides.
   */
   if (data_type == DFNT_INT16)
      data_buf = malloc (n_values * sizeof (int16));

   /*
   * Read and display the attribute values.
   */
   status = GRgetattr (ri_id, ri_att_index, (VOIDP)data_buf);

   printf ("\nAttribute %s: ", RI_ATTR_NAME);
   int_ptr = (int16 *)data_buf;
   for (value_index = 0; value_index < n_values; value_index++)
      printf ("%d ", int_ptr[value_index]);
   printf ("\n");

   /*
   * Free the space allocated for the data buffer.
   */
   free (data_buf);

   /*
   * Terminate access to the raster image and to the GR interface, and
   * close the file.
   */

   status = GRendaccess (ri_id);
   status = GRend (gr_id);
   status = Hclose (file_id);
   return 0;
}