/* Interpolate/Extrapolate 1.01 --- image filter plug-in for The Gimp
 * Copyright (C) 1996 Federico Mena Quintero
 *
 * You can contact me at quartic@polloux.fciencias.unam.mx
 * You can contact the original The Gimp authors at gimp@xcf.berkeley.edu
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */


#include <stdio.h>
#include <stdlib.h>

#include "gimp.h"


/* Useful macros */

#define MAX(a, b) ((a) > (b) ? (a) : (b))
#define CLAMP(a, x, b) (((x) <= (a)) ? (a) : (((x) <= (b)) ? (x) : (b)))


#ifndef _AIX
typedef unsigned char uchar;
#endif


/***** Local functions *****/

static void image_menu_callback(int item_id, void *client_data, void *call_data);
static void double_callback(int item_id, void *client_data, void *call_data);
static void ok_callback(int item_id, void *client_data, void *call_data);
static void cancel_callback(int item_id, void *client_data, void *call_data);

static void do_interpolate(Image img1, Image img2, double value);


/***** Local vars *****/

static char *prog_name;
static int   dialog_id;


/***** Functions *****/

/*****/

int
main(int argc, char **argv)
{
	Image  img1, img2;
	int    img1_menu_id, img2_menu_id;
	int    value_id;
	int    group_id, temp_id;
	char   buf[100];
	long   img1_id, img2_id;
	double value;

	/* Save program name */

	prog_name = argv[0];

	/* Initialize filter and continue if success */

	if (!gimp_init(argc, argv))
		return 0;

	img1_id = img2_id = 0;
	value = 0.0;

	dialog_id = gimp_new_dialog("Interpolate/Extrapolate");

	group_id = gimp_new_row_group(dialog_id, DEFAULT, NORMAL, "");

	img1_menu_id = gimp_new_image_menu(dialog_id, group_id,
					   IMAGE_CONSTRAIN_RGB | IMAGE_CONSTRAIN_GRAY,
					   "First Image");
	gimp_add_callback(dialog_id, img1_menu_id, image_menu_callback, &img1_id);


	img2_menu_id = gimp_new_image_menu(dialog_id, group_id,
					   IMAGE_CONSTRAIN_RGB | IMAGE_CONSTRAIN_GRAY,
					   "Second Image");
	gimp_add_callback(dialog_id, img2_menu_id, image_menu_callback, &img2_id);


	temp_id = gimp_new_column_group(dialog_id, group_id, NORMAL, "");
	gimp_new_label(dialog_id, temp_id, "Amount of first image:");
	sprintf(buf, "%0.3f", value);
	value_id = gimp_new_text(dialog_id, temp_id, buf);
	gimp_add_callback(dialog_id, value_id, double_callback, &value);

	gimp_add_callback(dialog_id, gimp_ok_item_id(dialog_id), ok_callback, NULL);

	gimp_add_callback(dialog_id, gimp_cancel_item_id(dialog_id), cancel_callback, NULL);

	if (gimp_show_dialog(dialog_id)) {
		img1 = gimp_get_input_image(img1_id);

		if (img2_id != img1_id)
			img2 = gimp_get_input_image(img2_id);
		else
			img2 = img1;

		if (img1 && img2) {
			gimp_init_progress("Interpolate/Extrapolate");

			do_interpolate(img1, img2, value);
		} /* if */
		
		if (img1)
			gimp_free_image(img1);

		if (img2 && (img1 != img2))
			gimp_free_image(img2);
	} /* if */

	gimp_quit();
	
	return 0;
} /* main */


/*****/

static void
image_menu_callback(int item_id, void *client_data, void *call_data)
{
	*((long *) client_data) = *((long *) call_data);
} /* image_menu_callback */


/*****/

static void
double_callback(int item_id, void *client_data, void *call_data)
{
	*((double *) client_data) = atof(call_data);
} /* double_callback */


/*****/

static void
ok_callback(int item_id, void *client_data, void *call_data)
{
	gimp_close_dialog(dialog_id, 1);
} /* ok_callback */


/*****/

static void
cancel_callback(int item_id, void *client_data, void *call_data)
{
	gimp_close_dialog(dialog_id, 0);
} /* cancel_callback */


/*****/

static void
do_interpolate(Image img1, Image img2, double value)
{
	Image     img_dest;
	ImageType dest_type;
	long  	  img1_channels, img2_channels, dest_channels;
	long  	  width, height;
	uchar 	 *src1, *src2, *dest;
	uchar 	  p1[3], p2[3];
	double    v;
	int   	  x, y, k;

	src1 = gimp_image_data(img1);
	src2 = gimp_image_data(img2);

	width  = gimp_image_width(img1);
	height = gimp_image_height(img1);

	img1_channels = gimp_image_channels(img1);
	img2_channels = gimp_image_channels(img2);
	dest_channels = MAX(img1_channels, img2_channels);

	if ((gimp_image_type(img1) == RGB_IMAGE)
	    || (gimp_image_type(img2) == RGB_IMAGE))
		dest_type = RGB_IMAGE;
	else
		dest_type = GRAY_IMAGE;

	img_dest  = gimp_new_image(0, width, height, dest_type);
	dest      = gimp_image_data(img_dest);

	for (y = 0; y < height; y++) {
		for (x = 0; x < width; x++) {
			/* Fetch and (if necessary) duplicate pixel from first image */
			
			for (k = 0; k < img1_channels; k++)
				p1[k] = *src1++;

			if (img1_channels < img2_channels)
				for (k = 1; k < img2_channels; k++)
					p1[k] = p1[0];

			/* Fetch and (if necessary) duplicate pixel from second image */
			
			for (k = 0; k < img2_channels; k++)
				p2[k] = *src2++;

			if (img2_channels < img1_channels)
				for (k = 1; k < img1_channels; k++)
					p2[k] = p2[0];

			/* Interpolate! */
			
			for (k = 0; k < dest_channels; k++) {
				v = value * p1[k] + (1.0 - value) * p2[k];
				*dest++ = CLAMP(0, v, 255);
			} /* for */
		} /* for */

		if (y % 64 == 0)
			gimp_do_progress(y, height);
	} /* for */

	gimp_display_image(img_dest);
	gimp_update_image(img_dest);
	gimp_free_image(img_dest);
} /* do_interpolate */