/*
 * Autocrop plug-in version 1.00
 * by Tim Newsome <drz@froody.bloke.com>
 * thanks to quartic for finding a nasty bug for me
 */

/* 1999/04/09 -- Sven Neumann <sven@gimp.org>
 * Fixed bad crash that occured when running on an entirely blank image.
 * Cleaned up the code a bit, while I was at it. 
 */ 

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#include "config.h"
#include "libgimp/gimp.h"
#include "libgimp/stdplugins-intl.h"

/* Declare local functions. */
static void query(void);
static void run(char *name,
		int nparams,
		GParam * param,
		int *nreturn_vals,
		GParam ** return_vals);
static int colors_equal(guchar *col1, guchar *col2, int bytes);
static int guess_bgcolor(GPixelRgn *pr, int width, int height, int bytes,
			 guchar *color);

static void doit(GDrawable *drawable, gint32);

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

gint bytes;
gint sx1, sy1, sx2, sy2;
int run_flag = 0;

MAIN()

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

  INIT_I18N();

  gimp_install_procedure("plug_in_autocrop",
			 "Automagically crops a picture.",
			 "",
			 "Tim Newsome",
			 "Tim Newsome",
			 "1997",
			 N_("<Image>/Image/Transforms/Autocrop"),
			 "RGB*, GRAY*, INDEXED*",
			 PROC_PLUG_IN,
			 nargs, nreturn_vals,
			 args, return_vals);
}

static void run(char *name, int n_params, GParam * param, int *nreturn_vals,
		GParam ** return_vals)
{
  static GParam values[1];
  GDrawable *drawable;
  GRunModeType run_mode;
  GStatusType status = STATUS_SUCCESS;
  gint32 image_id;
  
  *nreturn_vals = 1;
  *return_vals = values;
  
  run_mode = param[0].data.d_int32;

  INIT_I18N();
  
  if (run_mode == RUN_NONINTERACTIVE) {
    if (n_params != 3)
      status = STATUS_CALLING_ERROR;
  }

  if (status == STATUS_SUCCESS) {
    /*  Get the specified drawable  */
    drawable = gimp_drawable_get(param[2].data.d_drawable);
    image_id = param[1].data.d_image;
    
    /*  Make sure that the drawable is gray or RGB color  */
    if (gimp_drawable_is_rgb(drawable->id) ||
	gimp_drawable_is_gray(drawable->id)  ||
	gimp_drawable_is_indexed(drawable->id)) 
      {
	gimp_progress_init(_("Cropping..."));
	gimp_tile_cache_ntiles(2 * (drawable->width / gimp_tile_width() + 1));
	doit(drawable, image_id);
	
	if (run_mode != RUN_NONINTERACTIVE)
	  gimp_displays_flush();
      } 
    else 
      {
	status = STATUS_EXECUTION_ERROR;
      }

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

static void doit(GDrawable *drawable, gint32 image_id)
{
  GPixelRgn srcPR;
  gint width, height;
  int x, y, abort;
  gint32 nx, ny, nw, nh;
  guchar *buffer;
  guchar color[4] = {0, 0, 0, 0};
  int nreturn_vals;
  
  width = drawable->width;
  height = drawable->height;
  bytes = drawable->bpp;
  
  nx = 0;
  ny = 0;
  nw = width;
  nh = height;
  
  /*  initialize the pixel regions  */
  gimp_pixel_rgn_init(&srcPR, drawable, 0, 0, width, height, FALSE, FALSE);
  
  /* First, let's figure out what exactly to crop. */
  buffer = g_malloc((width > height ? width : height) * bytes);
  
  guess_bgcolor(&srcPR, width, height, bytes, color);
  
  /* Check how many of the top lines are uniform. */
  abort = 0;
  for (y = 0; y < height && !abort; y++) {
    gimp_pixel_rgn_get_row(&srcPR, buffer, 0, y, width);
    for (x = 0; x < width && !abort; x++) {
      abort = !colors_equal(color, buffer + x * bytes, bytes);
    }
  }
  if (y == height && !abort) {
    g_free(buffer);
    gimp_drawable_detach(drawable);
    return;
  }
  y--;
  ny = y;
  nh = height - y;
  
  gimp_progress_update(.25);
  
  /* Check how many of the bottom lines are uniform. */
  abort = 0;
  for (y = height - 1; y >= 0 && !abort; y--) {
    gimp_pixel_rgn_get_row(&srcPR, buffer, 0, y, width);
    for (x = 0; x < width && !abort; x++) {
      abort = !colors_equal(color, buffer + x * bytes, bytes);
    }
  }
  nh = y - ny + 2;
  
  gimp_progress_update(.5);
  
  /* Check how many of the left lines are uniform. */
  abort = 0;
  for (x = 0; x < width && !abort; x++) {
    gimp_pixel_rgn_get_col(&srcPR, buffer, x, ny, nh);
    for (y = 0; y < nh && !abort; y++) {
      abort = !colors_equal(color, buffer + y * bytes, bytes);
    }
  }
  x--;
  nx = x;
  nw = width - x;
  
  gimp_progress_update(.75);
  
  /* Check how many of the right lines are uniform. */
  abort = 0;
  for (x = width - 1; x >= 0 && !abort; x--) {
    gimp_pixel_rgn_get_col(&srcPR, buffer, x, ny, nh);
    for (y = 0; y < nh && !abort; y++) {
      abort = !colors_equal(color, buffer + y * bytes, bytes);
    }
  }
  nw = x - nx + 2;
  
  g_free(buffer);
  
  gimp_drawable_detach(drawable);
  if (nw != width || nh != height) {
    gimp_run_procedure("gimp_crop", &nreturn_vals,
		       PARAM_IMAGE, image_id,
		       PARAM_INT32, nw,
		       PARAM_INT32, nh,
		       PARAM_INT32, nx,
		       PARAM_INT32, ny,
		       PARAM_END);
  }
}

static int guess_bgcolor(GPixelRgn *pr, int width, int height, int bytes,
			 guchar *color) {
  guchar tl[4], tr[4], bl[4], br[4];
  
  gimp_pixel_rgn_get_pixel(pr, tl, 0, 0);
  gimp_pixel_rgn_get_pixel(pr, tr, width - 1, 0);
  gimp_pixel_rgn_get_pixel(pr, bl, 0, height - 1);
  gimp_pixel_rgn_get_pixel(pr, br, width - 1, height - 1);
  
  /* Algorithm pinched from pnmcrop.
   * To guess the background, first see if 3 corners are equal.
   * Then if two are equal.
   * Otherwise average the colors.
   */

  if (colors_equal(tr, bl, bytes) && colors_equal(tr, br, bytes)) {
    memcpy(color, tr, bytes);
    return 3;
  } else if (colors_equal(tl, bl, bytes) && colors_equal(tl, br, bytes)) {
    memcpy(color, tl, bytes);
    return 3;
  } else if (colors_equal(tl, tr, bytes) && colors_equal(tl, br, bytes)) {
    memcpy(color, tl, bytes);
    return 3;
  } else if (colors_equal(tl, tr, bytes) && colors_equal(tl, bl, bytes)) {
    memcpy(color, tl, bytes);
    return 3;
    
  } else if (colors_equal(tl, tr, bytes) || colors_equal(tl, bl, bytes) ||
	     colors_equal(tl, br, bytes)) {
    memcpy(color, tl, bytes);
    return 2;
  } else if (colors_equal(tr, bl, bytes) || colors_equal(tr, bl, bytes)) {
    memcpy(color, tr, bytes);
    return 2;
  } else if (colors_equal(br, bl, bytes)) {
    memcpy(color, br, bytes);
    return 2;
  } else {
    while (bytes--) {
      color[bytes] = (tl[bytes] + tr[bytes] + bl[bytes] + br[bytes]) / 4;
    }
    return 0;
  }
}

static int 
colors_equal(guchar *col1, guchar *col2, int bytes) {
  int equal = 1;
  int b;

  if ((bytes == 2 || bytes == 4) &&	/* HACK! */
      col1[bytes-1] == 0 &&
      col2[bytes-1] == 0) {
    return 1;				/* handle zero alpha */
  }
  
  for (b = 0; b < bytes; b++) {
    if (col1[b] != col2[b]) {
      equal = 0;
      break;
    }
  }
  
  return equal;
}