text: /*****************************************************************************
                                    pamdice
  ******************************************************************************
    Slice a Netpbm image vertically and/or horizontally into multiple images.
  
    By Bryan Henderson, San Jose CA 2001.01.31
  
    Contributed to the public domain.
  
  ******************************************************************************/
  
  #include <string.h>
  
  #include "pam.h"
  #include "shhopt.h"
  #include "nstring.h"
  #include "mallocvar.h"
  
  #define MAXFILENAMELEN 80
      /* Maximum number of characters we accept in filenames */
  
  struct cmdlineInfo {
      /* All the information the user supplied in the command line,
         in a form easy for the program to use.
      */
      const char * inputFilespec;  /* '-' if stdin */
      char * outstem; 
          /* null-terminated string, max MAXFILENAMELEN-10 characters */
      unsigned int sliceVertically;    /* boolean */
      unsigned int sliceHorizontally;  /* boolean */
      unsigned int width;    /* Meaningless if !sliceVertically */
      unsigned int height;   /* Meaningless if !sliceHorizontally */
      unsigned int hoverlap; 
          /* Meaningless if !sliceVertically.  Guaranteed < width */
      unsigned int voverlap; 
          /* Meaningless if !sliceHorizontally.  Guaranteed < height */
      unsigned int verbose;
  };
  
  
  static void
  parseCommandLine ( int argc, char ** argv,
                     struct cmdlineInfo * const cmdlineP ) {
  /*----------------------------------------------------------------------------
     parse program command line described in Unix standard form by argc
     and argv.  Return the information in the options as *cmdlineP.  
  
     If command line is internally inconsistent (invalid options, etc.),
     issue error message to stderr and abort program.
  
     Note that the strings we return are stored in the storage that
     was passed to us as the argv array.  We also trash *argv.
  -----------------------------------------------------------------------------*/
      optEntry *option_def;
          /* Instructions to optParseOptions3 on how to parse our options.
           */
      optStruct3 opt;
      
      unsigned int outstemSpec, hoverlapSpec, voverlapSpec;
      unsigned int option_def_index;
  
      MALLOCARRAY_NOFAIL(option_def, 100);
  
      option_def_index = 0;   /* incremented by OPTENT3 */
      OPTENT3(0, "width",       OPT_UINT,    &cmdlineP->width,       
              &cmdlineP->sliceVertically,       0 );
      OPTENT3(0, "height",      OPT_UINT,    &cmdlineP->height,
              &cmdlineP->sliceHorizontally,     0 );
      OPTENT3(0, "hoverlap",    OPT_UINT,    &cmdlineP->hoverlap,
              &hoverlapSpec,                    0 );
      OPTENT3(0, "voverlap",    OPT_UINT,    &cmdlineP->voverlap,
              &voverlapSpec,                    0 );
      OPTENT3(0, "outstem",     OPT_STRING,  &cmdlineP->outstem,
              &outstemSpec,                     0 );
      OPTENT3(0, "verbose",     OPT_FLAG,    NULL,
              &cmdlineP->verbose,               0 );
  
      opt.opt_table = option_def;
      opt.short_allowed = FALSE;  /* We have no short (old-fashioned) options */
      opt.allowNegNum = FALSE;  /* We have no parms that are negative numbers */
  
      optParseOptions3( &argc, argv, opt, sizeof(opt), 0 );
          /* Uses and sets argc, argv, and some of *cmdline_p and others. */
  
      if (cmdlineP->sliceVertically) {
          if (hoverlapSpec) {
              if (cmdlineP->hoverlap > cmdlineP->width - 1)
                  pm_error("-hoverlap value must be less than -width (%u).  "
                           "You specified %u.",
                           cmdlineP->width, cmdlineP->hoverlap);
          } else
              cmdlineP->hoverlap = 0;
      }
      if (cmdlineP->sliceHorizontally) {
          if (voverlapSpec) {
              if (cmdlineP->voverlap > cmdlineP->height - 1)
                  pm_error("-voverlap value must be less than -height (%u).  "
                           "You specified %u.",
                           cmdlineP->height, cmdlineP->voverlap);
          } else
              cmdlineP->voverlap = 0;
      }
  
      if (!outstemSpec)
          pm_error("You must specify the -outstem option to indicate where to "
                   "put the output images.");
      if (argc-1 < 1)
          cmdlineP->inputFilespec = "-";
      else if (argc-1 == 1)
          cmdlineP->inputFilespec = argv[1];
      else 
          pm_error("Progam takes at most 1 parameter: the file specification.  "
                   "You specified %d", argc-1);
  }
  
  
  
  static unsigned int
  divup(unsigned int const dividend,
        unsigned int const divisor) {
  /*----------------------------------------------------------------------------
     Divide 'dividend' by 'divisor' and round up to the next whole number.
  -----------------------------------------------------------------------------*/
      return (dividend + divisor - 1) / divisor;
  }
  
  
  
  static void
  computeSliceGeometry(struct cmdlineInfo const cmdline,
                       struct pam         const inpam,
                       bool               const verbose,
                       unsigned int *     const nHorizSliceP,
                       unsigned int *     const sliceHeightP,
                       unsigned int *     const bottomSliceHeightP,
                       unsigned int *     const nVertSliceP,
                       unsigned int *     const sliceWidthP,
                       unsigned int *     const rightSliceWidthP
                       ) {
  /*----------------------------------------------------------------------------
     Compute the geometry of the slices, both common slices and possibly
     smaller remainder slices at the top and right.
  -----------------------------------------------------------------------------*/
      if (cmdline.sliceHorizontally) {
          if (cmdline.height >= inpam.height)
              *nHorizSliceP = 1;
          else
              *nHorizSliceP = 1 + divup(inpam.height - cmdline.height, 
                                        cmdline.height - cmdline.voverlap);
          *sliceHeightP = cmdline.height;
      } else {
          *nHorizSliceP = 1;
          *sliceHeightP = inpam.height;
      }
  
      *bottomSliceHeightP = 
          inpam.height - (*nHorizSliceP-1) * (cmdline.height - cmdline.voverlap);
  
      if (cmdline.sliceVertically) {
          if (cmdline.width >= inpam.width)
              *nVertSliceP = 1;
          else
              *nVertSliceP = 1 + divup(inpam.width - cmdline.width, 
                                       cmdline.width - cmdline.hoverlap);
          *sliceWidthP = cmdline.width;
      } else {
          *nVertSliceP = 1;
          *sliceWidthP = inpam.width;
      }
  
      *rightSliceWidthP = 
          inpam.width - (*nVertSliceP-1) * (cmdline.width - cmdline.hoverlap);
  
      if (verbose) {
          pm_message("Creating %u images, %u across by %u down; "
                     "each %u w x %u h",
                     *nVertSliceP * *nHorizSliceP,
                     *nVertSliceP, *nHorizSliceP,
                     *sliceWidthP, *sliceHeightP);
          if (*rightSliceWidthP != *sliceWidthP)
              pm_message("Right vertical slice is only %u wide", 
                         *rightSliceWidthP);
          if (*bottomSliceHeightP != *sliceHeightP)
              pm_message("Bottom horizontal slice is only %u high",
                         *bottomSliceHeightP);
      }
  }
  
  
  
  static unsigned int
  ndigits(unsigned int const arg) {
  /*----------------------------------------------------------------------------
     Return the minimum number of digits it takes to represent the number
     'arg' in decimal.
  -----------------------------------------------------------------------------*/
      unsigned int leftover;
      unsigned int i;
  
      for (leftover = arg, i = 0; leftover > 0; leftover /= 10, ++i);
  
      return MAX(1, i);
  }
  
  
  
  static void
  computeOutputFilenameFormat(int           const format, 
                              char          const outstem[],
                              unsigned int  const nHorizSlice,
                              unsigned int  const nVertSlice,
                              const char ** const filenameFormatP) {
  
      const char * filenameSuffix;
  
      switch(PNM_FORMAT_TYPE(format)) {
      case PPM_TYPE: filenameSuffix = "ppm"; break;
      case PGM_TYPE: filenameSuffix = "pgm"; break;
      case PBM_TYPE: filenameSuffix = "pbm"; break;
      case PAM_TYPE: filenameSuffix = "pam"; break;
      default:       filenameSuffix = "";    break;
      }
      
      asprintfN(filenameFormatP, "%s_%%0%uu_%%0%uu.%s",
                outstem, ndigits(nHorizSlice), ndigits(nVertSlice),
                filenameSuffix);
  
      if (*filenameFormatP == NULL)
          pm_error("Unable to allocate memory for filename format string");
  }
  
  
  
  static void
  openOutStreams(struct pam   const inpam, 
                 struct pam         outpam[],
                 unsigned int const horizSlice, 
                 unsigned int const nHorizSlice,
                 unsigned int const nVertSlice,
                 unsigned int const sliceHeight, 
                 unsigned int const sliceWidth,
                 unsigned int const rightSliceWidth,
                 unsigned int const hOverlap,
                 char         const outstem[]) {
  /*----------------------------------------------------------------------------
     Open the output files for a single horizontal slice (there's one file
     for each vertical slice) and write the Netpbm headers to them.  Also
     compute the pam structures to control each.
  -----------------------------------------------------------------------------*/
      const char * filenameFormat;
      unsigned int vertSlice;
  
      computeOutputFilenameFormat(inpam.format, outstem, nHorizSlice, nVertSlice,
                                  &filenameFormat);
  
      for (vertSlice = 0; vertSlice < nVertSlice; ++vertSlice) {
          const char * filename;
  
          asprintfN(&filename, filenameFormat, horizSlice, vertSlice);
  
          if (filename == NULL)
              pm_error("Unable to allocate memory for output filename");
          else {
              outpam[vertSlice] = inpam;
              outpam[vertSlice].file = pm_openw(filename);
              
              outpam[vertSlice].width = 
                  vertSlice < nVertSlice-1 ? sliceWidth : rightSliceWidth;
              
              outpam[vertSlice].height = sliceHeight;
              
              pnm_writepaminit(&outpam[vertSlice]);
  
              strfree(filename);
          }
      }        
      strfree(filenameFormat);
  }
  
  
  
  static void
  closeOutFiles(struct pam pam[], unsigned int const nVertSlice) {
  
      unsigned int vertSlice;
      
      for (vertSlice = 0; vertSlice < nVertSlice; ++vertSlice)
          pm_close(pam[vertSlice].file);
  }
  
  static void
  sliceRow(tuple              inputRow[], 
           struct pam         outpam[], 
           unsigned int const nVertSlice,
           unsigned int const hOverlap) {
  /*----------------------------------------------------------------------------
     Distribute the row inputRow[] across the 'nVerticalSlice' output
     files described by outpam[].  Each outpam[x] tells how many columns
     of inputRow[] to take and what their composition is.
  
     'hOverlap', which is meaningful only when nVertSlice is greater than 1,
     is the amount by which slices overlap each other.
  -----------------------------------------------------------------------------*/
      tuple * outputRow;
      unsigned int vertSlice;
      unsigned int const sliceWidth = outpam[0].width;
      unsigned int const stride = 
          nVertSlice > 1 ? sliceWidth - hOverlap : sliceWidth;
  
      for (vertSlice = 0, outputRow = inputRow; 
           vertSlice < nVertSlice; 
           outputRow += stride, ++vertSlice) {
          pnm_writepamrow(&outpam[vertSlice], outputRow);
      }
  }
  
  
  /*----------------------------------------------------------------------------
     The input reader.  This just reads the input image row by row, except
     that it lets us back up up to a predefined amount (the window size).
     When we're overlapping horizontal slices, that's useful.  It's not as
     simple as just reading the entire image into memory at once, but uses
     a lot less memory.
  -----------------------------------------------------------------------------*/
  
  struct inputWindow {
      unsigned int windowSize;
      unsigned int firstRowInWindow;
      struct pam pam;
      tuple ** rows;
  };
  
  static void
  initInput(struct inputWindow * const inputWindowP,
            struct pam *         const pamP,
            unsigned int         const windowSize) {
      
      struct pam allocPam;  /* Just for allocating the window array */
      unsigned int i;
  
      inputWindowP->pam = *pamP;
      inputWindowP->windowSize = windowSize;
  
      allocPam = *pamP;
      allocPam.height = windowSize;
      
      inputWindowP->rows = pnm_allocpamarray(&allocPam);
  
      inputWindowP->firstRowInWindow = 0;
  
      /* Fill the window with the beginning of the image */
      for (i = 0; i < windowSize && i < pamP->height; ++i)
          pnm_readpamrow(&inputWindowP->pam, inputWindowP->rows[i]);
  }
  
  static void
  termInputWindow(struct inputWindow * const inputWindowP) {
  
      struct pam freePam;  /* Just for freeing window array */
  
      freePam = inputWindowP->pam;
      freePam.height = inputWindowP->windowSize;
  
      pnm_freepamarray(inputWindowP->rows, &freePam);
  }
  
  static tuple *
  getInputRow(struct inputWindow * const inputWindowP,
              unsigned int         const row) {
  
      if (row < inputWindowP->firstRowInWindow)
          pm_error("INTERNAL ERROR: attempt to back up too far with "
                   "getInputRow() (row %u)", row);
      if (row >= inputWindowP->pam.height)
          pm_error("INTERNAL ERROR: attempt to read beyond bottom of "
                   "input image (row %u)", row);
  
      while (row >= inputWindowP->firstRowInWindow + inputWindowP->windowSize) {
          tuple * const oldRow0 = inputWindowP->rows[0];
          unsigned int i;
          /* Slide the window down one row */
          for (i = 0; i < inputWindowP->windowSize - 1; ++i)
              inputWindowP->rows[i] = inputWindowP->rows[i+1];
          ++inputWindowP->firstRowInWindow;
  
          /* Read in the new last row in the window */
          inputWindowP->rows[i] = oldRow0;  /* Reuse the memory */
          pnm_readpamrow(&inputWindowP->pam, inputWindowP->rows[i]);
      }        
  
      return inputWindowP->rows[row - inputWindowP->firstRowInWindow];
  }
  
  /*-----  end of input reader ----------------------------------------------*/
  
  
  
  static void
  allocOutpam(unsigned int  const nVertSlice,
              struct pam ** const outpamArrayP) {
  
      struct pam * outpamArray;
  
      MALLOCARRAY(outpamArray, nVertSlice);
  
      if (outpamArray == NULL)
          pm_error("Unable to allocate array for %u output pam structures.",
                   nVertSlice);
  
      *outpamArrayP = outpamArray;
  }
  
  
  
  int
  main(int argc, char ** argv) {
  
      struct cmdlineInfo cmdline;
      FILE    *ifP;
      struct pam inpam;
      unsigned int horizSlice;
          /* Number of the current horizontal slice.  Slices are numbered
             sequentially starting at 0.
          */
      unsigned int sliceWidth;
          /* Width in pam columns of each vertical slice, except
             the rightmost slice, which may be narrower.  If we aren't slicing
             vertically, that means one slice, i.e. the slice width
             is the image width.  
          */
      unsigned int rightSliceWidth;
          /* Width in pam columns of the rightmost vertical slice. */
      unsigned int sliceHeight;
          /* Height in pam rows of each horizontal slice, except
             the bottom slice, which may be shorter.  If we aren't slicing
             horizontally, that means one slice, i.e. the slice height
             is the image height.  
          */
      unsigned int bottomSliceHeight;
          /* Height in pam rows of the bottom horizontal slice. */
      unsigned int nHorizSlice;
      unsigned int nVertSlice;
      struct inputWindow inputWindow;
      
      struct pam * outpam;
          /* malloc'ed.  outpam[x] is the pam structure that controls
             the current horizontal slice of vertical slice x.
          */
  
      pnm_init(&argc, argv);
      
      parseCommandLine(argc, argv, &cmdline);
          
      ifP = pm_openr(cmdline.inputFilespec);
  
      pnm_readpaminit(ifP, &inpam, PAM_STRUCT_SIZE(tuple_type));
  
      computeSliceGeometry(cmdline, inpam, !!cmdline.verbose,
                           &nHorizSlice, &sliceHeight, &bottomSliceHeight,
                           &nVertSlice, &sliceWidth, &rightSliceWidth);
  
      allocOutpam(nVertSlice, &outpam);
      
      initInput(&inputWindow, &inpam, 
                nHorizSlice > 1 ? cmdline.voverlap + 1 : 1);
  
      for (horizSlice = 0; horizSlice < nHorizSlice; ++horizSlice) {
          unsigned int const thisSliceFirstRow = 
              horizSlice * (sliceHeight - cmdline.voverlap);
          unsigned int const thisSliceHeight = 
              horizSlice < nHorizSlice-1 ? sliceHeight : bottomSliceHeight;
  
          unsigned int row;
  
          openOutStreams(inpam, outpam, horizSlice, nHorizSlice, nVertSlice, 
                         thisSliceHeight, sliceWidth, rightSliceWidth,
                         cmdline.hoverlap, cmdline.outstem);
  
          for (row = 0; row < thisSliceHeight; ++row) {
              tuple * const inputRow =
                  getInputRow(&inputWindow, thisSliceFirstRow + row);
              sliceRow(inputRow, outpam, nVertSlice, cmdline.hoverlap);
          }
          closeOutFiles(outpam, nVertSlice);
      }
  
      termInputWindow(&inputWindow);
  
      free(outpam);
  
      pm_close(ifP);
  
      return 0;
  }
  