/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2001-2002 by NaN Holding BV.
 * All rights reserved.
 *
 * The Original Code is: some of this file.
 *
 * ***** END GPL LICENSE BLOCK *****
 * */

/** \file blender/blenlib/intern/math_color_inline.c
 *  \ingroup bli
 */


#include "BLI_math_color.h"
#include "BLI_utildefines.h"

#include "math.h"

#ifndef __MATH_COLOR_INLINE_C__
#define __MATH_COLOR_INLINE_C__

/******************************** Color Space ********************************/

MINLINE void srgb_to_linearrgb_v3_v3(float linear[3], const float srgb[3])
{
	linear[0] = srgb_to_linearrgb(srgb[0]);
	linear[1] = srgb_to_linearrgb(srgb[1]);
	linear[2] = srgb_to_linearrgb(srgb[2]);
}

MINLINE void linearrgb_to_srgb_v3_v3(float srgb[3], const float linear[3])
{
	srgb[0] = linearrgb_to_srgb(linear[0]);
	srgb[1] = linearrgb_to_srgb(linear[1]);
	srgb[2] = linearrgb_to_srgb(linear[2]);
}

MINLINE void srgb_to_linearrgb_v4(float linear[4], const float srgb[4])
{
	srgb_to_linearrgb_v3_v3(linear, srgb);
	linear[3] = srgb[3];
}

MINLINE void linearrgb_to_srgb_v4(float srgb[4], const float linear[4])
{
	linearrgb_to_srgb_v3_v3(srgb, linear);
	srgb[3] = linear[3];
}

MINLINE void linearrgb_to_srgb_uchar3(unsigned char srgb[3], const float linear[3])
{
	float srgb_f[3];

	linearrgb_to_srgb_v3_v3(srgb_f, linear);
	F3TOCHAR3(srgb_f, srgb);
}

MINLINE void linearrgb_to_srgb_uchar4(unsigned char srgb[4], const float linear[4])
{
	float srgb_f[4];

	linearrgb_to_srgb_v4(srgb_f, linear);
	F4TOCHAR4(srgb_f, srgb);
}

/* predivide versions to work on associated/pre-multiplied alpha. if this should
 * be done or not depends on the background the image will be composited over,
 * ideally you would never do color space conversion on an image with alpha
 * because it is ill defined */

MINLINE void srgb_to_linearrgb_predivide_v4(float linear[4], const float srgb[4])
{
	float alpha, inv_alpha;

	if (srgb[3] == 1.0f || srgb[3] == 0.0f) {
		alpha = 1.0f;
		inv_alpha = 1.0f;
	}
	else {
		alpha = srgb[3];
		inv_alpha = 1.0f / alpha;
	}

	linear[0] = srgb_to_linearrgb(srgb[0] * inv_alpha) * alpha;
	linear[1] = srgb_to_linearrgb(srgb[1] * inv_alpha) * alpha;
	linear[2] = srgb_to_linearrgb(srgb[2] * inv_alpha) * alpha;
	linear[3] = srgb[3];
}

MINLINE void linearrgb_to_srgb_predivide_v4(float srgb[4], const float linear[4])
{
	float alpha, inv_alpha;

	if (linear[3] == 1.0f || linear[3] == 0.0f) {
		alpha = 1.0f;
		inv_alpha = 1.0f;
	}
	else {
		alpha = linear[3];
		inv_alpha = 1.0f / alpha;
	}

	srgb[0] = linearrgb_to_srgb(linear[0] * inv_alpha) * alpha;
	srgb[1] = linearrgb_to_srgb(linear[1] * inv_alpha) * alpha;
	srgb[2] = linearrgb_to_srgb(linear[2] * inv_alpha) * alpha;
	srgb[3] = linear[3];
}

/* LUT accelerated conversions */

extern float BLI_color_from_srgb_table[256];
extern unsigned short BLI_color_to_srgb_table[0x10000];

MINLINE unsigned short to_srgb_table_lookup(const float f)
{

	union {
		float f;
		unsigned short us[2];
	} tmp;
	tmp.f = f;
#ifdef __BIG_ENDIAN__
	return BLI_color_to_srgb_table[tmp.us[0]];
#else
	return BLI_color_to_srgb_table[tmp.us[1]];
#endif
}

MINLINE void linearrgb_to_srgb_ushort4(unsigned short srgb[4], const float linear[4])
{
	srgb[0] = to_srgb_table_lookup(linear[0]);
	srgb[1] = to_srgb_table_lookup(linear[1]);
	srgb[2] = to_srgb_table_lookup(linear[2]);
	srgb[3] = FTOUSHORT(linear[3]);
}

MINLINE void srgb_to_linearrgb_uchar4(float linear[4], const unsigned char srgb[4])
{
	linear[0] = BLI_color_from_srgb_table[srgb[0]];
	linear[1] = BLI_color_from_srgb_table[srgb[1]];
	linear[2] = BLI_color_from_srgb_table[srgb[2]];
	linear[3] = srgb[3] * (1.0f / 255.0f);
}

MINLINE void srgb_to_linearrgb_uchar4_predivide(float linear[4], const unsigned char srgb[4])
{
	float fsrgb[4];
	int i;

	if (srgb[3] == 255 || srgb[3] == 0) {
		srgb_to_linearrgb_uchar4(linear, srgb);
		return;
	}

	for (i = 0; i < 4; i++)
		fsrgb[i] = srgb[i] * (1.0f / 255.0f);

	srgb_to_linearrgb_predivide_v4(linear, fsrgb);
}

MINLINE void rgba_char_args_set(char col[4], const char r, const char g, const char b, const char a)
{
	col[0] = r;
	col[1] = g;
	col[2] = b;
	col[3] = a;
}

MINLINE void rgba_char_args_test_set(char col[4], const char r, const char g, const char b, const char a)
{
	if (col[3] == 0) {
		col[0] = r;
		col[1] = g;
		col[2] = b;
		col[3] = a;
	}
}

MINLINE void cpack_cpy_3ub(unsigned char r_col[3], const unsigned int pack)
{
	r_col[0] = ((pack) >>  0) & 0xFF;
	r_col[1] = ((pack) >>  8) & 0xFF;
	r_col[2] = ((pack) >> 16) & 0xFF;
}


/** \name RGB/Grayscale Functions
 *
 * \warning
 * These are only an approximation,
 * in almost _all_ cases, #IMB_colormanagement_get_luminance should be used instead.
 * however for screen-only colors which don't depend on the currently loaded profile - this is preferred.
 * Checking theme colors for contrast, etc. Basically anything outside the render pipeline.
 *
 * \{ */

/**
 * ITU-R BT.709 primaries
 * http://en.wikipedia.org/wiki/Relative_luminance
 *
 * Real values are:
 * ``Y = 0.2126390059(R) + 0.7151686788(G) + 0.0721923154(B)``
 * according to: "Derivation of Basic Television Color Equations", RP 177-1993
 *
 * As this sums slightly above 1.0, the document recommends to use:
 * ``0.2126(R) + 0.7152(G) + 0.0722(B)``, as used here.
 *
 * The high precision values are used to calculate the rounded byte weights so they add up to 255:
 * ``54(R) + 182(G) + 19(B)``
 */
MINLINE float rgb_to_grayscale(const float rgb[3])
{
	return  (0.2126f * rgb[0]) + (0.7152f * rgb[1]) + (0.0722f * rgb[2]);
}

MINLINE unsigned char rgb_to_grayscale_byte(const unsigned char rgb[3])
{
	return (unsigned char)(((54  * (unsigned short)rgb[0]) +
	                        (182 * (unsigned short)rgb[1]) +
	                        (19  * (unsigned short)rgb[2])) / 255);
}

/** \} */



MINLINE int compare_rgb_uchar(const unsigned char col_a[3], const unsigned char col_b[3], const int limit)
{
	const int r = (int)col_a[0] - (int)col_b[0];
	if (ABS(r) < limit) {
		const int g = (int)col_a[1] - (int)col_b[1];
		if (ABS(g) < limit) {
			const int b = (int)col_a[2] - (int)col_b[2];
			if (ABS(b) < limit) {
				return 1;
			}
		}
	}

	return 0;
}

MINLINE float dither_random_value(float s, float t)
{
	static float vec[2] = {12.9898f, 78.233f};
	float value;

	value = sinf(s * vec[0] + t * vec[1]) * 43758.5453f;
	return value - floorf(value);
}

MINLINE void float_to_byte_dither_v3(unsigned char b[3], const float f[3], float dither, float s, float t)
{
	float dither_value = dither_random_value(s, t) * 0.005f * dither;

	b[0] = FTOCHAR(dither_value + f[0]);
	b[1] = FTOCHAR(dither_value + f[1]);
	b[2] = FTOCHAR(dither_value + f[2]);
}

/**************** Alpha Transformations *****************/

MINLINE void premul_to_straight_v4_v4(float straight[4], const float premul[4])
{
	if (premul[3] == 0.0f || premul[3] == 1.0f) {
		straight[0] = premul[0];
		straight[1] = premul[1];
		straight[2] = premul[2];
		straight[3] = premul[3];
	}
	else {
		const float alpha_inv = 1.0f / premul[3];
		straight[0] = premul[0] * alpha_inv;
		straight[1] = premul[1] * alpha_inv;
		straight[2] = premul[2] * alpha_inv;
		straight[3] = premul[3];
	}
}

MINLINE void premul_to_straight_v4(float color[4])
{
	premul_to_straight_v4_v4(color, color);
}

MINLINE void straight_to_premul_v4_v4(float premul[4], const float straight[4])
{
	const float alpha = straight[3];
	premul[0] = straight[0] * alpha;
	premul[1] = straight[1] * alpha;
	premul[2] = straight[2] * alpha;
	premul[3] = straight[3];
}

MINLINE void straight_to_premul_v4(float color[4])
{
	straight_to_premul_v4_v4(color, color);
}

MINLINE void straight_uchar_to_premul_float(float result[4], const unsigned char color[4])
{
	const float alpha = color[3] * (1.0f / 255.0f);
	const float fac = alpha * (1.0f / 255.0f);

	result[0] = color[0] * fac;
	result[1] = color[1] * fac;
	result[2] = color[2] * fac;
	result[3] = alpha;
}

MINLINE void premul_float_to_straight_uchar(unsigned char *result, const float color[4])
{
	if (color[3] == 0.0f || color[3] == 1.0f) {
		result[0] = FTOCHAR(color[0]);
		result[1] = FTOCHAR(color[1]);
		result[2] = FTOCHAR(color[2]);
		result[3] = FTOCHAR(color[3]);
	}
	else {
		const float alpha_inv = 1.0f / color[3];

		/* hopefully this would be optimized */
		result[0] = FTOCHAR(color[0] * alpha_inv);
		result[1] = FTOCHAR(color[1] * alpha_inv);
		result[2] = FTOCHAR(color[2] * alpha_inv);
		result[3] = FTOCHAR(color[3]);
	}
}

#endif /* __MATH_COLOR_INLINE_C__ */