/**
* @file			trapcorr.c
* @brief		isosceles trapeze correction algorithm
* @author		Patrick Roth - roth@stettbacher.ch
* @copyright	Stettbacher Signal Processing AG
* 
* @remarks
*
* <PRE>
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
* </PRE>
*
*/

#include <stdio.h>
#include <string.h>
#include <math.h>

#include "color_pipe_private.h"



/**
 * Pixel value interpolation of RGB image (8 bit per color channel).
 * If a pixel coordinate with a fraction part is of interest, do interpolate the correct value from their neighbor's pixel.
 * 
 * E. g. the pixel coordinate x/y = 1.8/2.3 gives the following weights:
 *          +------+------+
 *          |      |      |
 *          | 14%  | 56%  |		14% = 20%*70%, 56% = 80%*70%
 *          |      |      |
 *          +------+------+
 *          |      |      |
 *          | 6%   | 24%  |		6% = 20%*30%, 24% = 80%*30%
 *          |      |      |
 *          +------+------+
 * 
 * The weights are applied to the neighors and the resulting pixel value is saved at the given location.
 * 
 * NOTE
 * The input and output image must have the same pixel size.
 * 
 * @param img_out On return: image with interpolated values
 * @param x saved interpolated pixel value at this x-coordinate
 * @param y saved interpolated pixel value at this y-coordinate
 * @param height image height of input and output image in number of pixels
 * @param width image width of input and output image in number of pixels
 * @param img_in input image to interpolate pixel values
 * @param coord_x x-coordinate to interpolate
 * @param coord_y y-coordinate to interpolate
 * @param scale_fact coordinates are scaled by this factor
 */
static void interpolate_rgb8_scalar(uint8_t *img_out, const int x, const int y, const int height, const int width,
						 const uint8_t *img_in, const int coord_x, const int coord_y, const int scale_fact)
#include "alg_interpolate_rgb_scalar.h"


/**
 * Pixel value interpolation of RGB image (16 bit per color channel).
 * If a pixel coordinate with a fraction part is of interest, do interpolate the correct value from their neighbor's pixel.
 * 
 * E. g. the pixel coordinate x/y = 1.8/2.3 gives the following weights:
 *          +------+------+
 *          |      |      |
 *          | 14%  | 56%  |		14% = 20%*70%, 56% = 80%*70%
 *          |      |      |
 *          +------+------+
 *          |      |      |
 *          | 6%   | 24%  |		6% = 20%*30%, 24% = 80%*30%
 *          |      |      |
 *          +------+------+
 * 
 * The weights are applied to the neighors and the resulting pixel value is saved at the given location.
 * 
 * NOTE
 * The input and output image must have the same pixel size.
 * 
 * @param img_out On return: image with interpolated values
 * @param x saved interpolated pixel value at this x-coordinate
 * @param y saved interpolated pixel value at this y-coordinate
 * @param height image height of input and output image in number of pixels
 * @param width image width of input and output image in number of pixels
 * @param img_in input image to interpolate pixel values
 * @param coord_x x-coordinate to interpolate
 * @param coord_y y-coordinate to interpolate
 * @param scale_fact coordinates are scaled by this factor
 */
static void interpolate_rgb16_scalar(uint16_t *img_out, const int x, const int y, const int height, const int width,
						  const uint16_t *img_in, const int coord_x, const int coord_y, const int scale_fact)
#include "alg_interpolate_rgb_scalar.h"


/**
 * Pixel value interpolation of monochrome image (8 bit per pixel).
 * If a pixel coordinate with a fraction part is of interest, do interpolate the correct value from their neighbor's pixel.
 * 
 * E. g. the pixel coordinate x/y = 1.8/2.3 gives the following weights:
 *          +------+------+
 *          |      |      |
 *          | 14%  | 56%  |		14% = 20%*70%, 56% = 80%*70%
 *          |      |      |
 *          +------+------+
 *          |      |      |
 *          | 6%   | 24%  |		6% = 20%*30%, 24% = 80%*30%
 *          |      |      |
 *          +------+------+
 * 
 * The weights are applied to the neighors and the resulting pixel value is saved at the given location.
 * 
 * NOTE
 * The input and output image must have the same pixel size.
 * 
 * @param img_out On return: image with interpolated values
 * @param x saved interpolated pixel value at this x-coordinate
 * @param y saved interpolated pixel value at this y-coordinate
 * @param height image height of input and output image in number of pixels
 * @param width image width of input and output image in number of pixels
 * @param img_in input image to interpolate pixel values
 * @param coord_x x-coordinate to interpolate
 * @param coord_y y-coordinate to interpolate
 * @param scale_fact coordinates are scaled by this factor
 */
static void interpolate_mono8_scalar(uint8_t *img_out, const int x, const int y, const int height, const int width,
						 const uint8_t *img_in, const int coord_x, const int coord_y, const int scale_fact)
#include "alg_interpolate_mono_scalar.h"


/**
 * Pixel value interpolation of monochrome image (16 bit per pixel).
 * If a pixel coordinate with a fraction part is of interest, do interpolate the correct value from their neighbor's pixel.
 * 
 * E. g. the pixel coordinate x/y = 1.8/2.3 gives the following weights:
 *          +------+------+
 *          |      |      |
 *          | 14%  | 56%  |		14% = 20%*70%, 56% = 80%*70%
 *          |      |      |
 *          +------+------+
 *          |      |      |
 *          | 6%   | 24%  |		6% = 20%*30%, 24% = 80%*30%
 *          |      |      |
 *          +------+------+
 * 
 * The weights are applied to the neighors and the resulting pixel value is saved at the given location.
 * 
 * NOTE
 * The input and output image must have the same pixel size.
 * 
 * @param img_out On return: image with interpolated values
 * @param x saved interpolated pixel value at this x-coordinate
 * @param y saved interpolated pixel value at this y-coordinate
 * @param height image height of input and output image in number of pixels
 * @param width image width of input and output image in number of pixels
 * @param img_in input image to interpolate pixel values
 * @param coord_x x-coordinate to interpolate
 * @param coord_y y-coordinate to interpolate
 * @param scale_fact coordinates are scaled by this factor
 */
static void interpolate_mono16_scalar(uint16_t *img_out, const int x, const int y, const int height, const int width,
						  const uint16_t *img_in, const int coord_x, const int coord_y, const int scale_fact)
#include "alg_interpolate_mono_scalar.h"


/**
 * Apply iosceles trapez correction.
 * 
 * @param data correction data
 */ 
static void correct(struct trapcorr_data_t *data) {
	int x, y, x_corr, y_corr;
	const int width = data->width;
	const int height = data->height;
	int bit_channel =  data->bit_channel;
	struct coord_t *map = data->map;
	void *img_calib = data->img_out;
	void *img_uncalib = data->img_in;
	const int scale_fact = data->map_scale_fact;
	const int is_color = data->is_color;
	
	for(y = 0; y < height; y++) {
		for(x = 0; x < width; x++) {
			x_corr = map->x;
			y_corr = map->y;
			map++;
			
			if(bit_channel <= 8) {
				if(is_color) {
					interpolate_rgb8_scalar(img_calib, x, y, height, width, img_uncalib, x_corr, y_corr, scale_fact);
				}
				else {
					interpolate_mono8_scalar(img_calib, x, y, height, width, img_uncalib, x_corr, y_corr, scale_fact);
				}
			}
			else if(bit_channel <= 16) {
				if(is_color) {
					interpolate_rgb16_scalar(img_calib, x, y, height, width, img_uncalib, x_corr, y_corr, scale_fact);
				}
				else {
					interpolate_mono16_scalar(img_calib, x, y, height, width, img_uncalib, x_corr, y_corr, scale_fact);
				}
			}
		}
	}
}


/**
 * Initialze perspective correction map.
 * 
 * @param data required correction data
 */ 
static void init_map(struct trapcorr_data_t *data) {
	
	int x, y;
	struct coord_t *map = data->map;
	const int scale_fact = (1 << (data->map_scale_fact));
	const int width = data->width;
	const int height = data->height;
	float p, p_i, row_scale, x_corr, y_corr;
	int x_start, x_end;
	int shrink_upper;
	
	// convert -100.0...+100.0 ---> 0.0...2.0
	const float fact = data->wh/100.0f+1.0f;
	
	/*
	 * Checking whether we shrink upper or lower horizontal
	 * trapeze line.
	 */ 
	if(data->wh <= 1.0f) {
		// upper line shrinks
		shrink_upper = 1;
		p = fact * (width/2.0f);
	}
	else {
		// lower line shrinks
		shrink_upper = 0;
		p = (2.0f - fact) * (width/2.0f);
	}
	
	/*
	 * We'll loop through image with y-axis symmetrically centered.
	 * So the image is horizontally shifted to left. Do calculate
	 * the start and end values on x-axis.
	 */ 
	if((width%2) == 0) {
		// even width
		x_start = (-1)*width/2;
		x_end = width/2-1;
	}
	else {
		// odd width
		x_start = (-1)*(width-1)/2;
		x_end = (width-1)/2;
	}
	
	// loop through image
	for(y = 0; y < height; y++) {
		if(shrink_upper) {
			p_i = ((width/2.0f - p) / height) * y + p;
		}
		else {
			p_i = (-1.0f*((width/2.0f - p) / height)) * y + width/2.0f;
		}
				
		row_scale = 2.0f * p_i / width;
		
		// we don't correct vertically
		y_corr = y;
		
		for(x = x_start; x <= x_end; x++) {
			x_corr = x/row_scale;
			
			// trapeze is horizontally symmetrically centered --> shift right
			x_corr -= x_start;
			
			// apply scaling factor
			map->x = (int)roundf(x_corr*scale_fact);
			map->y = (int)roundf(y_corr*scale_fact);
			map++;
		}
	}
}


/**
 * Apply iosceles trapez correction to given image type.
 * 
 * @param trapcorr_data required data for trapez correction
 * @return 0 on success otherwise -1
 */
int trapcorr(struct trapcorr_data_t *trapcorr_data) {
	
	/*
	 * Create perspective correction map if needed.
	 */ 
	if(trapcorr_data->map_init == 0) {
		trapcorr_data->map_scale_fact = 9;	// scale by 9 means 2^9 = 512
		init_map(trapcorr_data);
		trapcorr_data->map_init = 1;
	}
	
	// apply perspective correction
	correct(trapcorr_data);
	return 0;
}