Pointer images

      #include <gandalf/image/image_pointer.h>

Gandalf pointer images allow storage and manipulation of a 2D array of generic pointers, stored as void * values. Pointer images have format GAN_GREY_LEVEL_IMAGE and type GAN_POINTER. All the standard functions given above. Note that when a pointer image is freed, the pointer pixels are left ``hanging'', so they should if necessary be freed first before freeing the pointer image. This code fragment illustrates the use of pointer image functions.

      Gan_Image *pImage;
      Gan_Vector4 *apv4Vector[5], *pv4Vector;
      int iCount, iRow, iCol;

      /* allocate 300x200 pointer image, and initialise all pointer "pixels"
         to NULL */
      pImage = gan_image_alloc_p ( 300, 200 );
      gan_image_fill_zero(pImage);

      /* allocate some pointers to 4-vectors */
      for ( iCount = 5-1; iCount >= 0; iCount-- )
         apv4Vector[iCount] = gan_malloc_object(Gan_Vector4);

      /* set some pointer "pixels" */
      gan_image_set_pix_p ( pImage, 271,  39, apv4Vector[0] );
      gan_image_set_pix_p ( pImage,  30, 120, apv4Vector[1] );
      gan_image_set_pix_p ( pImage,  78,  49, apv4Vector[2] );
      gan_image_set_pix_p ( pImage, 147, 120, apv4Vector[3] );
      gan_image_set_pix_p ( pImage, 232, 130, apv4Vector[4] );

      /* now free allocated vectors by searching for non-NULL values in the
         image */
      for ( iRow = (int)pImage->height-1; iRow >= 0; iRow-- )
         for ( iCol = (int)pImage->width-1; iCol >= 0; iCol-- )
            if ( (pv4Vector = gan_image_get_pix_p ( pImage, iRow, iCol )) != NULL )
               free(pv4Vector);

      /* free image */
      gan_image_free ( pImage );