/* Tiler v0.31
 * 22 May 1997
 * Tim Rowley <tor@cs.brown.edu>
 */

/* TODO:
 * + better basis function
 * + optimize
 */

/* History:
 * v0.1: initial version
 * v0.2: fix edge conditions
 * v0.3: port to 0.99 API
 * v0.31: small bugfix
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "libgimp/gimp.h"

/* Declare local functions.
 */
static void query(void);
static void run(char *name, int nparams, GParam *param, int *nreturn_vals,
		GParam **return_vals);
static void tile(GDrawable *drawable);
static int scale(int width, int height, int x, int y, int data);


GPlugInInfo PLUG_IN_INFO =
{
  NULL,    /* init_proc */
  NULL,    /* quit_proc */
  query,   /* query_proc */
  run,     /* run_proc */
};

MAIN ()

static void
query ()
{
  static GParamDef args[] =
  {
    { PARAM_INT32, "run_mode", "Interactive, non-interactive" },
    { PARAM_IMAGE, "image", "Input image (unused)" },
    { PARAM_DRAWABLE, "drawable", "Input drawable" },
  };
  static GParamDef *return_vals = NULL;
  static int nargs = sizeof (args) / sizeof (args[0]);
  static int nreturn_vals = 0;

  gimp_install_procedure ("plug_in_make_seamless",
			  "Seamless tile creation",
			  "This plugin creates a seamless tileable from the input image",
			  "Tim Rowley",
			  "Tim Rowley",
			  "1997",
			  "<Image>/Filters/Map/Make Seamless",
			  "RGB*, GRAY*",
			  PROC_PLUG_IN,
			  nargs, nreturn_vals,
			  args, return_vals);
}


static void
run (char    *name,
     int      nparams,
     GParam  *param,
     int     *nreturn_vals,
     GParam **return_vals)
{
  static GParam values[1];
  GDrawable *drawable;
  GRunModeType run_mode;
  GStatusType status = STATUS_SUCCESS;

  run_mode = param[0].data.d_int32;

  /*  Get the specified drawable  */
  drawable = gimp_drawable_get (param[2].data.d_drawable);

  /*  Make sure that the drawable is gray or RGB color  */
  if (gimp_drawable_color (drawable->id) || gimp_drawable_gray (drawable->id))
    {
      gimp_tile_cache_ntiles (2 * (drawable->width / gimp_tile_width () + 1));
      tile(drawable);

      if (run_mode != RUN_NONINTERACTIVE)
	gimp_displays_flush ();
    }
  else
    {
      /* gimp_message ("laplace: cannot operate on indexed color images"); */
      status = STATUS_EXECUTION_ERROR;
    }

  *nreturn_vals = 1;
  *return_vals = values;

  values[0].type = PARAM_STATUS;
  values[0].data.d_status = status;

  gimp_drawable_detach (drawable);
}



static int scale(int width, int height, int x, int y, int data)
{
  int A = width/2-1;
  int B = height/2-1;
  int a, b;

  if (x<width/2)
    a = width/2-x-1; 
  else if ((x==width/2) && (width&1))
      return data;
  else
    a = x-width/2-(width&1);

  if (y<height/2)
    b = height/2-y-1; 
  else if ((y==height/2) && (height&1))
    return data;
  else
    b = y-height/2-(height&1);
  
  if ((B*a<A*b) || ((B*a==A*b) && (a&1))) {
    a = A-a;
    b = B-b;
    if (a==A)
      return data;
    else
      return data-((data*(A*B-a*B))/(A*b+A*B-a*B));
  }
  else {
    if (a==A)
      return 0;
    else 
      return (data*(A*B-a*B))/(A*b+A*B-a*B);
  }
}


static void
tile(GDrawable *drawable)
{
  long width, height;
  long bytes;
  long val;
  int wodd, hodd;
  GPixelRgn srcPR, destPR;
  gint x1, y1, x2, y2;
  gint row, col, x, y, c;
  guchar *cur_row, *dest_cur, *dest_top, *dest_bot;

  /* Get the input */

  gimp_drawable_mask_bounds(drawable->id, &x1, &y1, &x2, &y2);
  gimp_progress_init("Tiler");
  
  width = drawable->width;
  height = drawable->height;
  bytes = drawable->bpp;

  /*  allocate row buffers  */
  cur_row = (guchar *) malloc ((x2 - x1) * bytes);
  dest_cur = (guchar *) malloc ((x2 - x1) * bytes);
  dest_top = (guchar *) malloc ((x2 - x1) * bytes);
  dest_bot = (guchar *) malloc ((x2 - x1) * bytes);

  gimp_pixel_rgn_init (&srcPR, drawable, 0, 0, width, height, FALSE, FALSE);
  gimp_pixel_rgn_init (&destPR, drawable, 0, 0, width, height, TRUE, TRUE);

  y = y2-y1;
  x = x2-x1;

  wodd = x&1;
  hodd = y&1;

  for (row = 0; row <y; row++)
  {
    gimp_pixel_rgn_get_row(&destPR, dest_cur, x1, y1+row, (x2-x1));
    memset(dest_cur, 0, x*bytes);
    gimp_pixel_rgn_set_row(&destPR, dest_cur, x1, y1+row, (x2-x1));
  }

  for (row = 0; row < y; row++)
  {
    gimp_pixel_rgn_get_row(&srcPR, cur_row, x1, y1+row, (x2-x1));
    gimp_pixel_rgn_get_row(&destPR, dest_cur, x1, y1+row, (x2-x1));
    if (row>=y/2+hodd)
      gimp_pixel_rgn_get_row(&destPR, dest_top, x1, y1+(row-y/2-hodd), (x2-x1));
    if (row<y/2)
      gimp_pixel_rgn_get_row(&destPR, dest_bot, x1, y1+(row+y/2+hodd), (x2-x1));

    for (col = 0; col < x; col++)
    {
      for (c=0; c<bytes; c++) {
	val = scale(x, y, col, row, cur_row[col*bytes+c]);

	/* Main image */
	dest_cur[col*bytes+c] += val;
	/* top left */
	if ((col>=x/2+wodd) && (row>=y/2+hodd))
	  dest_top[(col-x/2-wodd)*bytes+c] += val;
	/* top right */
	if ((col<x/2) && (row>=y/2+hodd))
	  dest_top[(x/2+col+wodd)*bytes+c] += val;
	/* bottom left */
	if ((col>=x/2+wodd) && (row<y/2))
	  dest_bot[(col-x/2-wodd)*bytes+c] += val;
	/* bottom right */
	if ((col<x/2) && (row<y/2))
	  dest_bot[(col+x/2+wodd)*bytes+c] += val;
      }
    }

    gimp_pixel_rgn_set_row(&destPR, dest_cur, x1, y1+row, (x2-x1));
    if (row>=y/2+hodd)
      gimp_pixel_rgn_set_row(&destPR, dest_top, x1, y1+(row-y/2-hodd), (x2-x1));
    if (row<y/2)
      gimp_pixel_rgn_set_row(&destPR, dest_bot, x1, y1+(row+y/2+hodd), (x2-x1));

    if ((row % 5) == 0)
      gimp_progress_update((double)row/(double)(y2-y1));
  }

  gimp_drawable_flush(drawable);
  gimp_drawable_merge_shadow(drawable->id, TRUE);
  gimp_drawable_update(drawable->id, x1, y1, (x2-x1), (y2-y1));
}