/* 
 * leptonica-projective-transform - Example for pixProjectiveSampled()
 *
 * Copyright (C) 2013  Antonio Ospite <ospite@studenti.unina.it>
 *
 * 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 3 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, see <http://www.gnu.org/licenses/>.
 */

#include <stdio.h>
#include <errno.h>
#include <leptonica/allheaders.h>

#define WIDTH 800
#define HEIGHT 480

#define X_CORRECTION 200

int main(int argc, char *argv[])
{
	int ret;
	PIX *image;
	BOX *viewport;
	PIX *cropped_image;
	PTA *src;
	PTA *dst;
	l_float32 *transform_coeffs;
	PIX *transformed_image;

	if (argc != 2) {
		fprintf(stderr, "usage: %s <image>\n", argv[0]);
		ret = -EINVAL;
		goto out;
	}

	image = pixRead(argv[1]);
	if (image == NULL) {
		fprintf(stderr, "Cannot load image\n");
		ret = -EINVAL;
		goto out;
	}

	src = ptaCreate(4);
	if (src == NULL) {
		ret = -ENOMEM;
		goto out_destroy_image;
	}
	ptaAddPt(src, 0, 0);
	ptaAddPt(src, WIDTH, 0);
	ptaAddPt(src, WIDTH, HEIGHT);
	ptaAddPt(src, 0, HEIGHT);

	dst = ptaCreate(4);
	if (dst == NULL) {
		ret = -ENOMEM;
		goto out_destroy_pta_src;
	}
	ptaAddPt(dst, X_CORRECTION, 0);
	ptaAddPt(dst, WIDTH - X_CORRECTION, 0);
	ptaAddPt(dst, WIDTH, HEIGHT);
	ptaAddPt(dst, 0, HEIGHT);

	transform_coeffs = NULL;
	ret = getProjectiveXformCoeffs(dst, src, &transform_coeffs);
	if (ret != 0) {
		ret = -ENOMEM;
		goto out_destroy_pta_dst;
	}

	/* Transform only a part of the whole image */
	viewport = boxCreateValid(0, 0, WIDTH, HEIGHT);
	if (viewport == NULL) {
		ret = -EINVAL;
		goto out_free_transform_coeffs;
	}
	cropped_image = pixClipRectangle(image, viewport, NULL);
	if (cropped_image == NULL) {
		ret = -EINVAL;
		goto out_destroy_viewport;
	}

	/* Apply the perspective transformation */
	transformed_image = pixProjectiveSampled(cropped_image, transform_coeffs, L_BRING_IN_BLACK);
	if (transformed_image == NULL) {
		fprintf(stderr, "Cannot create transformed image\n");
		ret = -EINVAL;
		goto out_free_cropped_image;
	}

	ret = pixWrite("transformed_image.jpg", transformed_image, IFF_JFIF_JPEG);
	if (ret != 0) {
		ret = -EINVAL;
		goto cleanup;
	}

	ret = 0;

cleanup:
	pixDestroy(&transformed_image);
out_free_cropped_image:
	pixDestroy(&cropped_image);
out_destroy_viewport:
	boxDestroy(&viewport);
out_free_transform_coeffs:
	FREE(transform_coeffs);
out_destroy_pta_dst:
	ptaDestroy(&dst);
out_destroy_pta_src:
	ptaDestroy(&src);
out_destroy_image:
	pixDestroy(&image);
out:
	return ret;
}