/* SPDX-License-Identifier: GPL-2.0-or-later
 * Copyright 2001-2002 NaN Holding BV. All rights reserved. */

/** \file
 * \ingroup bli
 */

#include "BLI_math_base.h"
#include "BLI_math_color.h"
#include "BLI_math_color_blend.h"
#include "BLI_math_vector.h"
#include "BLI_utildefines.h"

#ifndef __MATH_COLOR_BLEND_INLINE_C__
#  define __MATH_COLOR_BLEND_INLINE_C__

/* don't add any saturation to a completely black and white image */
#  define EPS_SATURATION 0.0005f
#  define EPS_ALPHA 0.0005f

/***************************** Color Blending ********************************
 *
 * - byte colors are assumed to be straight alpha
 * - byte colors uses to do >>8 (same as /256) but actually should do /255,
 *   otherwise get quick darkening due to rounding
 * - divide_round_i is also used to avoid darkening due to integers always
 *   rounding down
 * - float colors are assumed to be premultiplied alpha
 */

/* straight alpha byte blending modes */

MINLINE void blend_color_mix_byte(uchar dst[4], const uchar src1[4], const uchar src2[4])
{
  if (src2[3] != 0) {
    /* straight over operation */
    const int t = src2[3];
    const int mt = 255 - t;
    int tmp[4];

    tmp[0] = (mt * src1[3] * src1[0]) + (t * 255 * src2[0]);
    tmp[1] = (mt * src1[3] * src1[1]) + (t * 255 * src2[1]);
    tmp[2] = (mt * src1[3] * src1[2]) + (t * 255 * src2[2]);
    tmp[3] = (mt * src1[3]) + (t * 255);

    dst[0] = (uchar)divide_round_i(tmp[0], tmp[3]);
    dst[1] = (uchar)divide_round_i(tmp[1], tmp[3]);
    dst[2] = (uchar)divide_round_i(tmp[2], tmp[3]);
    dst[3] = (uchar)divide_round_i(tmp[3], 255);
  }
  else {
    /* no op */
    copy_v4_v4_uchar(dst, src1);
  }
}

MINLINE void blend_color_add_byte(uchar dst[4], const uchar src1[4], const uchar src2[4])
{
  if (src2[3] != 0) {
    /* straight add operation */
    const int t = src2[3];
    int tmp[3];

    tmp[0] = (src1[0] * 255) + (src2[0] * t);
    tmp[1] = (src1[1] * 255) + (src2[1] * t);
    tmp[2] = (src1[2] * 255) + (src2[2] * t);

    dst[0] = (uchar)min_ii(divide_round_i(tmp[0], 255), 255);
    dst[1] = (uchar)min_ii(divide_round_i(tmp[1], 255), 255);
    dst[2] = (uchar)min_ii(divide_round_i(tmp[2], 255), 255);
    dst[3] = src1[3];
  }
  else {
    /* no op */
    copy_v4_v4_uchar(dst, src1);
  }
}

MINLINE void blend_color_sub_byte(uchar dst[4], const uchar src1[4], const uchar src2[4])
{
  if (src2[3] != 0) {
    /* straight sub operation */
    const int t = src2[3];
    int tmp[3];

    tmp[0] = (src1[0] * 255) - (src2[0] * t);
    tmp[1] = (src1[1] * 255) - (src2[1] * t);
    tmp[2] = (src1[2] * 255) - (src2[2] * t);

    dst[0] = (uchar)max_ii(divide_round_i(tmp[0], 255), 0);
    dst[1] = (uchar)max_ii(divide_round_i(tmp[1], 255), 0);
    dst[2] = (uchar)max_ii(divide_round_i(tmp[2], 255), 0);
    dst[3] = src1[3];
  }
  else {
    /* no op */
    copy_v4_v4_uchar(dst, src1);
  }
}

MINLINE void blend_color_mul_byte(uchar dst[4], const uchar src1[4], const uchar src2[4])
{
  if (src2[3] != 0) {
    /* straight multiply operation */
    const int t = src2[3];
    const int mt = 255 - t;
    int tmp[3];

    tmp[0] = (mt * src1[0] * 255) + (t * src1[0] * src2[0]);
    tmp[1] = (mt * src1[1] * 255) + (t * src1[1] * src2[1]);
    tmp[2] = (mt * src1[2] * 255) + (t * src1[2] * src2[2]);

    dst[0] = (uchar)divide_round_i(tmp[0], 255 * 255);
    dst[1] = (uchar)divide_round_i(tmp[1], 255 * 255);
    dst[2] = (uchar)divide_round_i(tmp[2], 255 * 255);
    dst[3] = src1[3];
  }
  else {
    /* no op */
    copy_v4_v4_uchar(dst, src1);
  }
}

MINLINE void blend_color_lighten_byte(uchar dst[4], const uchar src1[4], const uchar src2[4])
{
  if (src2[3] != 0) {
    /* straight lighten operation */
    const int t = src2[3];
    const int mt = 255 - t;
    int tmp[3];

    tmp[0] = (mt * src1[0]) + (t * max_ii(src1[0], src2[0]));
    tmp[1] = (mt * src1[1]) + (t * max_ii(src1[1], src2[1]));
    tmp[2] = (mt * src1[2]) + (t * max_ii(src1[2], src2[2]));

    dst[0] = (uchar)divide_round_i(tmp[0], 255);
    dst[1] = (uchar)divide_round_i(tmp[1], 255);
    dst[2] = (uchar)divide_round_i(tmp[2], 255);
    dst[3] = src1[3];
  }
  else {
    /* no op */
    copy_v4_v4_uchar(dst, src1);
  }
}

MINLINE void blend_color_darken_byte(uchar dst[4], const uchar src1[4], const uchar src2[4])
{
  if (src2[3] != 0) {
    /* straight darken operation */
    const int t = src2[3];
    const int mt = 255 - t;
    int tmp[3];

    tmp[0] = (mt * src1[0]) + (t * min_ii(src1[0], src2[0]));
    tmp[1] = (mt * src1[1]) + (t * min_ii(src1[1], src2[1]));
    tmp[2] = (mt * src1[2]) + (t * min_ii(src1[2], src2[2]));

    dst[0] = (uchar)divide_round_i(tmp[0], 255);
    dst[1] = (uchar)divide_round_i(tmp[1], 255);
    dst[2] = (uchar)divide_round_i(tmp[2], 255);
    dst[3] = src1[3];
  }
  else {
    /* no op */
    copy_v4_v4_uchar(dst, src1);
  }
}

MINLINE void blend_color_erase_alpha_byte(uchar dst[4], const uchar src1[4], const uchar src2[4])
{
  if (src2[3] != 0) {
    /* straight so just modify alpha channel */
    const int t = src2[3];

    dst[0] = src1[0];
    dst[1] = src1[1];
    dst[2] = src1[2];
    dst[3] = (uchar)max_ii(src1[3] - divide_round_i(t * src2[3], 255), 0);
  }
  else {
    /* no op */
    copy_v4_v4_uchar(dst, src1);
  }
}

MINLINE void blend_color_add_alpha_byte(uchar dst[4], const uchar src1[4], const uchar src2[4])
{
  if (src2[3] != 0) {
    /* straight so just modify alpha channel */
    const int t = src2[3];

    dst[0] = src1[0];
    dst[1] = src1[1];
    dst[2] = src1[2];
    dst[3] = (uchar)min_ii(src1[3] + divide_round_i(t * src2[3], 255), 255);
  }
  else {
    /* no op */
    copy_v4_v4_uchar(dst, src1);
  }
}

MINLINE void blend_color_overlay_byte(uchar dst[4], const uchar src1[4], const uchar src2[4])
{
  const int fac = (int)src2[3];
  if (fac != 0) {
    const int mfac = 255 - fac;
    int i = 3;

    while (i--) {
      int temp;

      if (src1[i] > 127) {
        temp = 255 - ((255 - 2 * (src1[i] - 127)) * (255 - src2[i]) / 255);
      }
      else {
        temp = (2 * src1[i] * src2[i]) >> 8;
      }
      dst[i] = (uchar)min_ii((temp * fac + src1[i] * mfac) / 255, 255);
    }
  }
  else {
    /* no op */
    copy_v4_v4_uchar(dst, src1);
  }
}

MINLINE void blend_color_hardlight_byte(uchar dst[4], const uchar src1[4], const uchar src2[4])
{
  const int fac = (int)src2[3];
  if (fac != 0) {
    const int mfac = 255 - fac;
    int i = 3;

    while (i--) {
      int temp;

      if (src2[i] > 127) {
        temp = 255 - ((255 - 2 * (src2[i] - 127)) * (255 - src1[i]) / 255);
      }
      else {
        temp = (2 * src2[i] * src1[i]) >> 8;
      }
      dst[i] = (uchar)min_ii((temp * fac + src1[i] * mfac) / 255, 255);
    }
  }
  else {
    /* no op */
    copy_v4_v4_uchar(dst, src1);
  }
}

MINLINE void blend_color_burn_byte(uchar dst[4], const uchar src1[4], const uchar src2[4])
{
  const int fac = src2[3];
  if (fac != 0) {
    const int mfac = 255 - fac;
    int i = 3;

    while (i--) {
      const int temp = (src2[i] == 0) ? 0 : max_ii(255 - ((255 - src1[i]) * 255) / src2[i], 0);
      dst[i] = (uchar)((temp * fac + src1[i] * mfac) / 255);
    }
  }
  else {
    /* no op */
    copy_v4_v4_uchar(dst, src1);
  }
}

MINLINE void blend_color_linearburn_byte(uchar dst[4], const uchar src1[4], const uchar src2[4])
{
  const int fac = src2[3];
  if (fac != 0) {
    const int mfac = 255 - fac;
    int i = 3;

    while (i--) {
      const int temp = max_ii(src1[i] + src2[i] - 255, 0);
      dst[i] = (uchar)((temp * fac + src1[i] * mfac) / 255);
    }
  }
  else {
    /* no op */
    copy_v4_v4_uchar(dst, src1);
  }
}

MINLINE void blend_color_dodge_byte(uchar dst[4], const uchar src1[4], const uchar src2[4])
{
  const int fac = src2[3];
  if (fac != 0) {
    const int mfac = 255 - fac;
    int i = 3;

    while (i--) {
      const int temp = (src2[i] == 255) ? 255 : min_ii((src1[i] * 255) / (255 - src2[i]), 255);
      dst[i] = (uchar)((temp * fac + src1[i] * mfac) / 255);
    }
  }
  else {
    /* no op */
    copy_v4_v4_uchar(dst, src1);
  }
}

MINLINE void blend_color_screen_byte(uchar dst[4], const uchar src1[4], const uchar src2[4])
{
  const int fac = src2[3];
  if (fac != 0) {
    const int mfac = 255 - fac;
    int i = 3;

    while (i--) {
      const int temp = max_ii(255 - (((255 - src1[i]) * (255 - src2[i])) / 255), 0);
      dst[i] = (uchar)((temp * fac + src1[i] * mfac) / 255);
    }
  }
  else {
    /* no op */
    copy_v4_v4_uchar(dst, src1);
  }
}

MINLINE void blend_color_softlight_byte(uchar dst[4], const uchar src1[4], const uchar src2[4])
{
  const int fac = src2[3];
  if (fac != 0) {
    const int mfac = 255 - fac;
    int i = 3;

    while (i--) {
      int temp;

      if (src1[i] < 127) {
        temp = ((2 * ((src2[i] / 2) + 64)) * src1[i]) / 255;
      }
      else {
        temp = 255 - (2 * (255 - ((src2[i] / 2) + 64)) * (255 - src1[i]) / 255);
      }
      dst[i] = (uchar)((temp * fac + src1[i] * mfac) / 255);
    }
  }
  else {
    /* no op */
    copy_v4_v4_uchar(dst, src1);
  }
}

MINLINE void blend_color_pinlight_byte(uchar dst[4], const uchar src1[4], const uchar src2[4])
{
  const int fac = src2[3];
  if (fac != 0) {
    const int mfac = 255 - fac;
    int i = 3;

    while (i--) {
      int temp;

      if (src2[i] > 127) {
        temp = max_ii(2 * (src2[i] - 127), src1[i]);
      }
      else {
        temp = min_ii(2 * src2[i], src1[i]);
      }
      dst[i] = (uchar)((min_ii(temp, 255) * fac + src1[i] * mfac) / 255);
    }
  }
  else {
    /* no op */
    copy_v4_v4_uchar(dst, src1);
  }
}

MINLINE void blend_color_linearlight_byte(uchar dst[4], const uchar src1[4], const uchar src2[4])
{
  const int fac = src2[3];
  if (fac != 0) {
    const int mfac = 255 - fac;
    int i = 3;

    while (i--) {
      int temp;

      if (src2[i] > 127) {
        temp = min_ii(src1[i] + 2 * (src2[i] - 127), 255);
      }
      else {
        temp = max_ii(src1[i] + 2 * src2[i] - 255, 0);
      }
      dst[i] = (uchar)((temp * fac + src1[i] * mfac) / 255);
    }
  }
  else {
    /* no op */
    copy_v4_v4_uchar(dst, src1);
  }
}

MINLINE void blend_color_vividlight_byte(uchar dst[4], const uchar src1[4], const uchar src2[4])
{
  const int fac = src2[3];
  if (fac != 0) {
    const int mfac = 255 - fac;
    int i = 3;

    while (i--) {
      int temp;

      if (src2[i] == 255) {
        temp = (src1[i] == 0) ? 127 : 255;
      }
      else if (src2[i] == 0) {
        temp = (src1[i] == 255) ? 127 : 0;
      }
      else if (src2[i] > 127) {
        temp = min_ii(((src1[i]) * 255) / (2 * (255 - src2[i])), 255);
      }
      else {
        temp = max_ii(255 - ((255 - src1[i]) * 255 / (2 * src2[i])), 0);
      }
      dst[i] = (uchar)((temp * fac + src1[i] * mfac) / 255);
    }
  }
  else {
    /* no op */
    copy_v4_v4_uchar(dst, src1);
  }
}

MINLINE void blend_color_difference_byte(uchar dst[4], const uchar src1[4], const uchar src2[4])
{
  const int fac = src2[3];
  if (fac != 0) {
    const int mfac = 255 - fac;
    int i = 3;

    while (i--) {
      const int temp = abs(src1[i] - src2[i]);
      dst[i] = (uchar)((temp * fac + src1[i] * mfac) / 255);
    }
  }
  else {
    /* no op */
    copy_v4_v4_uchar(dst, src1);
  }
}

MINLINE void blend_color_exclusion_byte(uchar dst[4], const uchar src1[4], const uchar src2[4])
{
  const int fac = src2[3];
  if (fac != 0) {
    const int mfac = 255 - fac;
    int i = 3;

    while (i--) {
      const int temp = 127 - min_ii(((2 * (src1[i] - 127) * (src2[i] - 127)) / 255), 127);
      dst[i] = (uchar)((temp * fac + src1[i] * mfac) / 255);
    }
  }
  else {
    /* no op */
    copy_v4_v4_uchar(dst, src1);
  }
}

MINLINE void blend_color_color_byte(uchar dst[4], const uchar src1[4], const uchar src2[4])
{
  const int fac = src2[3];
  if (fac != 0) {
    const int mfac = 255 - fac;
    float h1, s1, v1;
    float h2, s2, v2;
    float r, g, b;
    rgb_to_hsv(src1[0] / 255.0f, src1[1] / 255.0f, src1[2] / 255.0f, &h1, &s1, &v1);
    rgb_to_hsv(src2[0] / 255.0f, src2[1] / 255.0f, src2[2] / 255.0f, &h2, &s2, &v2);

    h1 = h2;
    s1 = s2;

    hsv_to_rgb(h1, s1, v1, &r, &g, &b);

    dst[0] = (uchar)(((int)(r * 255.0f) * fac + src1[0] * mfac) / 255);
    dst[1] = (uchar)(((int)(g * 255.0f) * fac + src1[1] * mfac) / 255);
    dst[2] = (uchar)(((int)(b * 255.0f) * fac + src1[2] * mfac) / 255);
  }
  else {
    /* no op */
    copy_v4_v4_uchar(dst, src1);
  }
}

MINLINE void blend_color_hue_byte(uchar dst[4], const uchar src1[4], const uchar src2[4])
{
  const int fac = src2[3];
  if (fac != 0) {
    const int mfac = 255 - fac;
    float h1, s1, v1;
    float h2, s2, v2;
    float r, g, b;
    rgb_to_hsv(src1[0] / 255.0f, src1[1] / 255.0f, src1[2] / 255.0f, &h1, &s1, &v1);
    rgb_to_hsv(src2[0] / 255.0f, src2[1] / 255.0f, src2[2] / 255.0f, &h2, &s2, &v2);

    h1 = h2;

    hsv_to_rgb(h1, s1, v1, &r, &g, &b);

    dst[0] = (uchar)(((int)(r * 255.0f) * fac + src1[0] * mfac) / 255);
    dst[1] = (uchar)(((int)(g * 255.0f) * fac + src1[1] * mfac) / 255);
    dst[2] = (uchar)(((int)(b * 255.0f) * fac + src1[2] * mfac) / 255);
  }
  else {
    /* no op */
    copy_v4_v4_uchar(dst, src1);
  }
}

MINLINE void blend_color_saturation_byte(uchar dst[4], const uchar src1[4], const uchar src2[4])
{
  const int fac = src2[3];
  if (fac != 0) {
    const int mfac = 255 - fac;
    float h1, s1, v1;
    float h2, s2, v2;
    float r, g, b;
    rgb_to_hsv(src1[0] / 255.0f, src1[1] / 255.0f, src1[2] / 255.0f, &h1, &s1, &v1);
    rgb_to_hsv(src2[0] / 255.0f, src2[1] / 255.0f, src2[2] / 255.0f, &h2, &s2, &v2);

    if (s1 > EPS_SATURATION) {
      s1 = s2;
    }

    hsv_to_rgb(h1, s1, v1, &r, &g, &b);

    dst[0] = (uchar)(((int)(r * 255.0f) * fac + src1[0] * mfac) / 255);
    dst[1] = (uchar)(((int)(g * 255.0f) * fac + src1[1] * mfac) / 255);
    dst[2] = (uchar)(((int)(b * 255.0f) * fac + src1[2] * mfac) / 255);
  }
  else {
    /* no op */
    copy_v4_v4_uchar(dst, src1);
  }
}

MINLINE void blend_color_luminosity_byte(uchar dst[4], const uchar src1[4], const uchar src2[4])
{
  const int fac = src2[3];
  if (fac != 0) {
    const int mfac = 255 - fac;
    float h1, s1, v1;
    float h2, s2, v2;
    float r, g, b;
    rgb_to_hsv(src1[0] / 255.0f, src1[1] / 255.0f, src1[2] / 255.0f, &h1, &s1, &v1);
    rgb_to_hsv(src2[0] / 255.0f, src2[1] / 255.0f, src2[2] / 255.0f, &h2, &s2, &v2);

    v1 = v2;

    hsv_to_rgb(h1, s1, v1, &r, &g, &b);

    dst[0] = (uchar)(((int)(r * 255.0f) * fac + src1[0] * mfac) / 255);
    dst[1] = (uchar)(((int)(g * 255.0f) * fac + src1[1] * mfac) / 255);
    dst[2] = (uchar)(((int)(b * 255.0f) * fac + src1[2] * mfac) / 255);
  }
  else {
    /* no op */
    copy_v4_v4_uchar(dst, src1);
  }
}

MINLINE void blend_color_interpolate_byte(uchar dst[4],
                                          const uchar src1[4],
                                          const uchar src2[4],
                                          float ft)
{
  /* do color interpolation, but in premultiplied space so that RGB colors
   * from zero alpha regions have no influence */
  const int t = (int)(255 * ft);
  const int mt = 255 - t;
  int tmp = (mt * src1[3] + t * src2[3]);

  if (tmp > 0) {
    dst[0] = (uchar)divide_round_i(mt * src1[0] * src1[3] + t * src2[0] * src2[3], tmp);
    dst[1] = (uchar)divide_round_i(mt * src1[1] * src1[3] + t * src2[1] * src2[3], tmp);
    dst[2] = (uchar)divide_round_i(mt * src1[2] * src1[3] + t * src2[2] * src2[3], tmp);
    dst[3] = (uchar)divide_round_i(tmp, 255);
  }
  else {
    copy_v4_v4_uchar(dst, src1);
    dst[3] = 0;
  }
}

/* premultiplied alpha float blending modes */

MINLINE void blend_color_mix_float(float dst[4], const float src1[4], const float src2[4])
{
  if (src2[3] != 0.0f) {
    /* premul over operation */
    const float t = src2[3];
    const float mt = 1.0f - t;

    dst[0] = mt * src1[0] + src2[0];
    dst[1] = mt * src1[1] + src2[1];
    dst[2] = mt * src1[2] + src2[2];
    dst[3] = mt * src1[3] + t;
  }
  else {
    /* no op */
    copy_v4_v4(dst, src1);
  }
}

MINLINE void blend_color_add_float(float dst[4], const float src1[4], const float src2[4])
{
  if (src2[3] != 0.0f) {
    /* unpremul > add > premul, simplified */
    dst[0] = src1[0] + src2[0] * src1[3];
    dst[1] = src1[1] + src2[1] * src1[3];
    dst[2] = src1[2] + src2[2] * src1[3];
    dst[3] = src1[3];
  }
  else {
    /* no op */
    copy_v4_v4(dst, src1);
  }
}

MINLINE void blend_color_sub_float(float dst[4], const float src1[4], const float src2[4])
{
  if (src2[3] != 0.0f) {
    /* unpremul > subtract > premul, simplified */
    dst[0] = max_ff(src1[0] - src2[0] * src1[3], 0.0f);
    dst[1] = max_ff(src1[1] - src2[1] * src1[3], 0.0f);
    dst[2] = max_ff(src1[2] - src2[2] * src1[3], 0.0f);
    dst[3] = src1[3];
  }
  else {
    /* no op */
    copy_v4_v4(dst, src1);
  }
}

MINLINE void blend_color_mul_float(float dst[4], const float src1[4], const float src2[4])
{
  if (src2[3] != 0.0f) {
    /* unpremul > multiply > premul, simplified */
    const float t = src2[3];
    const float mt = 1.0f - t;

    dst[0] = mt * src1[0] + src1[0] * src2[0] * src1[3];
    dst[1] = mt * src1[1] + src1[1] * src2[1] * src1[3];
    dst[2] = mt * src1[2] + src1[2] * src2[2] * src1[3];
    dst[3] = src1[3];
  }
  else {
    /* no op */
    copy_v4_v4(dst, src1);
  }
}

MINLINE void blend_color_lighten_float(float dst[4], const float src1[4], const float src2[4])
{
  if (src2[3] != 0.0f) {
    /* remap src2 to have same alpha as src1 premultiplied, take maximum of
     * src1 and src2, then blend it with src1 */
    const float t = src2[3];
    const float mt = 1.0f - t;
    const float map_alpha = src1[3] / src2[3];

    dst[0] = mt * src1[0] + t * max_ff(src1[0], src2[0] * map_alpha);
    dst[1] = mt * src1[1] + t * max_ff(src1[1], src2[1] * map_alpha);
    dst[2] = mt * src1[2] + t * max_ff(src1[2], src2[2] * map_alpha);
    dst[3] = src1[3];
  }
  else {
    /* no op */
    copy_v4_v4(dst, src1);
  }
}

MINLINE void blend_color_darken_float(float dst[4], const float src1[4], const float src2[4])
{
  if (src2[3] != 0.0f) {
    /* remap src2 to have same alpha as src1 premultiplied, take minimum of
     * src1 and src2, then blend it with src1 */
    const float t = src2[3];
    const float mt = 1.0f - t;
    const float map_alpha = src1[3] / src2[3];

    dst[0] = mt * src1[0] + t * min_ff(src1[0], src2[0] * map_alpha);
    dst[1] = mt * src1[1] + t * min_ff(src1[1], src2[1] * map_alpha);
    dst[2] = mt * src1[2] + t * min_ff(src1[2], src2[2] * map_alpha);
    dst[3] = src1[3];
  }
  else {
    /* no op */
    copy_v4_v4(dst, src1);
  }
}

MINLINE void blend_color_erase_alpha_float(float dst[4], const float src1[4], const float src2[4])
{
  if (src2[3] != 0.0f && src1[3] > 0.0f) {
    /* subtract alpha and remap RGB channels to match */
    float alpha = max_ff(src1[3] - src2[3], 0.0f);
    float map_alpha;

    if (alpha <= EPS_ALPHA) {
      alpha = 0.0f;
    }

    map_alpha = alpha / src1[3];

    dst[0] = src1[0] * map_alpha;
    dst[1] = src1[1] * map_alpha;
    dst[2] = src1[2] * map_alpha;
    dst[3] = alpha;
  }
  else {
    /* no op */
    copy_v4_v4(dst, src1);
  }
}

MINLINE void blend_color_add_alpha_float(float dst[4], const float src1[4], const float src2[4])
{
  if (src2[3] != 0.0f && src1[3] < 1.0f) {
    /* add alpha and remap RGB channels to match */
    float alpha = min_ff(src1[3] + src2[3], 1.0f);
    float map_alpha;

    if (alpha >= 1.0f - EPS_ALPHA) {
      alpha = 1.0f;
    }

    map_alpha = (src1[3] > 0.0f) ? alpha / src1[3] : 1.0f;

    dst[0] = src1[0] * map_alpha;
    dst[1] = src1[1] * map_alpha;
    dst[2] = src1[2] * map_alpha;
    dst[3] = alpha;
  }
  else {
    /* no op */
    copy_v4_v4(dst, src1);
  }
}

MINLINE void blend_color_overlay_float(float dst[4], const float src1[4], const float src2[4])
{
  const float fac = src2[3];
  if (fac != 0.0f) {
    const float mfac = 1.0f - fac;
    int i = 3;

    while (i--) {
      float temp;

      if (src1[i] > 0.5f) {
        temp = 1.0f - (1.0f - 2.0f * (src1[i] - 0.5f)) * (1.0f - src2[i]);
      }
      else {
        temp = 2.0f * src1[i] * src2[i];
      }
      dst[i] = min_ff(temp * fac + src1[i] * mfac, 1.0f);
    }
  }
  else {
    /* no op */
    copy_v4_v4(dst, src1);
  }
}

MINLINE void blend_color_hardlight_float(float dst[4], const float src1[4], const float src2[4])
{
  const float fac = src2[3];
  if (fac != 0.0f) {
    const float mfac = 1.0f - fac;
    int i = 3;

    while (i--) {
      float temp;

      if (src2[i] > 0.5f) {
        temp = 1.0f - ((1.0f - 2.0f * (src2[i] - 0.5f)) * (1.0f - src1[i]));
      }
      else {
        temp = 2.0f * src2[i] * src1[i];
      }
      dst[i] = min_ff((temp * fac + src1[i] * mfac) / 1.0f, 1.0f);
    }
  }
  else {
    /* no op */
    copy_v4_v4(dst, src1);
  }
}

MINLINE void blend_color_burn_float(float dst[4], const float src1[4], const float src2[4])
{
  const float fac = src2[3];
  if (fac != 0.0f) {
    const float mfac = 1.0f - fac;
    int i = 3;

    while (i--) {
      const float temp = (src2[i] == 0.0f) ? 0.0f :
                                             max_ff(1.0f - ((1.0f - src1[i]) / src2[i]), 0.0f);
      dst[i] = (temp * fac + src1[i] * mfac);
    }
  }
  else {
    /* no op */
    copy_v4_v4(dst, src1);
  }
}

MINLINE void blend_color_linearburn_float(float dst[4], const float src1[4], const float src2[4])
{
  const float fac = src2[3];
  if (fac != 0.0f) {
    const float mfac = 1.0f - fac;
    int i = 3;

    while (i--) {
      const float temp = max_ff(src1[i] + src2[i] - 1.0f, 0.0f);
      dst[i] = (temp * fac + src1[i] * mfac);
    }
  }
  else {
    /* no op */
    copy_v4_v4(dst, src1);
  }
}

MINLINE void blend_color_dodge_float(float dst[4], const float src1[4], const float src2[4])
{
  const float fac = src2[3];
  if (fac != 0.0f) {
    const float mfac = 1.0f - fac;
    int i = 3;

    while (i--) {
      const float temp = (src2[i] >= 1.0f) ? 1.0f : min_ff(src1[i] / (1.0f - src2[i]), 1.0f);
      dst[i] = (temp * fac + src1[i] * mfac);
    }
  }
  else {
    /* no op */
    copy_v4_v4(dst, src1);
  }
}

MINLINE void blend_color_screen_float(float dst[4], const float src1[4], const float src2[4])
{
  const float fac = src2[3];
  if (fac != 0.0f) {
    const float mfac = 1.0f - fac;
    int i = 3;

    while (i--) {
      const float temp = max_ff(1.0f - ((1.0f - src1[i]) * (1.0f - src2[i])), 0.0f);
      dst[i] = (temp * fac + src1[i] * mfac);
    }
  }
  else {
    /* no op */
    copy_v4_v4(dst, src1);
  }
}

MINLINE void blend_color_softlight_float(float dst[4], const float src1[4], const float src2[4])
{
  const float fac = src2[3];
  if (fac != 0.0f) {
    const float mfac = 1.0f - fac;
    int i = 3;

    while (i--) {
      float screen = 1.0f - (1.0f - src1[i]) * (1.0f - src2[i]);
      float soft_light = ((1.0f - src1[i]) * src2[i] + screen) * src1[i];
      dst[i] = src1[i] * mfac + soft_light * fac;
    }
  }
  else {
    /* no op */
    copy_v4_v4(dst, src1);
  }
}

MINLINE void blend_color_pinlight_float(float dst[4], const float src1[4], const float src2[4])
{
  const float fac = src2[3];
  if (fac != 0.0f) {
    const float mfac = 1.0f - fac;
    int i = 3;

    while (i--) {
      float temp;

      if (src2[i] > 0.5f) {
        temp = max_ff(2.0f * (src2[i] - 0.5f), src1[i]);
      }
      else {
        temp = min_ff(2.0f * src2[i], src1[i]);
      }
      dst[i] = (temp * fac + src1[i] * mfac);
    }
  }
  else {
    /* no op */
    copy_v4_v4(dst, src1);
  }
}

MINLINE void blend_color_linearlight_float(float dst[4], const float src1[4], const float src2[4])
{
  const float fac = src2[3];
  if (fac != 0.0f) {
    const float mfac = 1.0f - fac;
    int i = 3;

    while (i--) {
      float temp;

      if (src2[i] > 0.5f) {
        temp = min_ff(src1[i] + 2.0f * (src2[i] - 0.5f), 1.0f);
      }
      else {
        temp = max_ff(src1[i] + 2.0f * src2[i] - 1.0f, 0.0f);
      }
      dst[i] = (temp * fac + src1[i] * mfac);
    }
  }
  else {
    /* no op */
    copy_v4_v4(dst, src1);
  }
}

MINLINE void blend_color_vividlight_float(float dst[4], const float src1[4], const float src2[4])
{
  const float fac = src2[3];
  if (fac != 0.0f) {
    const float mfac = 1.0f - fac;
    int i = 3;

    while (i--) {
      float temp;

      if (src2[i] == 1.0f) {
        temp = (src1[i] == 0.0f) ? 0.5f : 1.0f;
      }
      else if (src2[i] == 0.0f) {
        temp = (src1[i] == 1.0f) ? 0.5f : 0.0f;
      }
      else if (src2[i] > 0.5f) {
        temp = min_ff(((src1[i]) * 1.0f) / (2.0f * (1.0f - src2[i])), 1.0f);
      }
      else {
        temp = max_ff(1.0f - ((1.0f - src1[i]) * 1.0f / (2.0f * src2[i])), 0.0f);
      }
      dst[i] = (temp * fac + src1[i] * mfac);
    }
  }
  else {
    /* no op */
    copy_v4_v4(dst, src1);
  }
}

MINLINE void blend_color_difference_float(float dst[4], const float src1[4], const float src2[4])
{
  const float fac = src2[3];
  if (fac != 0.0f) {
    const float mfac = 1.0f - fac;
    int i = 3;

    while (i--) {
      dst[i] = (fabsf(src1[i] - src2[i]) * fac + src1[i] * mfac);
    }
  }
  else {
    /* no op */
    copy_v4_v4(dst, src1);
  }
}

MINLINE void blend_color_exclusion_float(float dst[4], const float src1[4], const float src2[4])
{
  const float fac = src2[3];
  if (fac != 0.0f) {
    const float mfac = 1.0f - fac;
    int i = 3;

    while (i--) {
      const float temp = 0.5f - ((2 * (src1[i] - 0.5f) * (src2[i] - 0.5f)));
      dst[i] = (temp * fac + src1[i] * mfac);
    }
  }
  else {
    /* no op */
    copy_v4_v4(dst, src1);
  }
}

MINLINE void blend_color_color_float(float dst[4], const float src1[4], const float src2[4])
{
  const float fac = src2[3];
  if (fac != 0.0f) {
    const float mfac = 1.0f - fac;
    float h1, s1, v1;
    float h2, s2, v2;
    float r, g, b;

    rgb_to_hsv(src1[0], src1[1], src1[2], &h1, &s1, &v1);
    rgb_to_hsv(src2[0], src2[1], src2[2], &h2, &s2, &v2);

    h1 = h2;
    s1 = s2;

    hsv_to_rgb(h1, s1, v1, &r, &g, &b);

    dst[0] = (r * fac + src1[0] * mfac);
    dst[1] = (g * fac + src1[1] * mfac);
    dst[2] = (b * fac + src1[2] * mfac);
  }
  else {
    /* no op */
    copy_v4_v4(dst, src1);
  }
}

MINLINE void blend_color_hue_float(float dst[4], const float src1[4], const float src2[4])
{
  const float fac = src2[3];
  if (fac != 0.0f) {
    const float mfac = 1.0f - fac;
    float h1, s1, v1;
    float h2, s2, v2;
    float r, g, b;

    rgb_to_hsv(src1[0], src1[1], src1[2], &h1, &s1, &v1);
    rgb_to_hsv(src2[0], src2[1], src2[2], &h2, &s2, &v2);

    h1 = h2;

    hsv_to_rgb(h1, s1, v1, &r, &g, &b);

    dst[0] = (r * fac + src1[0] * mfac);
    dst[1] = (g * fac + src1[1] * mfac);
    dst[2] = (b * fac + src1[2] * mfac);
  }
  else {
    /* no op */
    copy_v4_v4(dst, src1);
  }
}

MINLINE void blend_color_saturation_float(float dst[4], const float src1[4], const float src2[4])
{
  const float fac = src2[3];
  if (fac != 0.0f) {
    const float mfac = 1.0f - fac;
    float h1, s1, v1;
    float h2, s2, v2;
    float r, g, b;

    rgb_to_hsv(src1[0], src1[1], src1[2], &h1, &s1, &v1);
    rgb_to_hsv(src2[0], src2[1], src2[2], &h2, &s2, &v2);

    if (s1 > EPS_SATURATION) {
      s1 = s2;
    }
    hsv_to_rgb(h1, s1, v1, &r, &g, &b);

    dst[0] = (r * fac + src1[0] * mfac);
    dst[1] = (g * fac + src1[1] * mfac);
    dst[2] = (b * fac + src1[2] * mfac);
  }
  else {
    /* no op */
    copy_v4_v4(dst, src1);
  }
}

MINLINE void blend_color_luminosity_float(float dst[4], const float src1[4], const float src2[4])
{
  const float fac = src2[3];
  if (fac != 0.0f) {
    const float mfac = 1.0f - fac;
    float h1, s1, v1;
    float h2, s2, v2;
    float r, g, b;

    rgb_to_hsv(src1[0], src1[1], src1[2], &h1, &s1, &v1);
    rgb_to_hsv(src2[0], src2[1], src2[2], &h2, &s2, &v2);

    v1 = v2;
    hsv_to_rgb(h1, s1, v1, &r, &g, &b);

    dst[0] = (r * fac + src1[0] * mfac);
    dst[1] = (g * fac + src1[1] * mfac);
    dst[2] = (b * fac + src1[2] * mfac);
  }
  else {
    /* no op */
    copy_v4_v4(dst, src1);
  }
}

MINLINE void blend_color_interpolate_float(float dst[4],
                                           const float src1[4],
                                           const float src2[4],
                                           float t)
{
  /* interpolation, colors are premultiplied so it goes fine */
  const float mt = 1.0f - t;

  dst[0] = mt * src1[0] + t * src2[0];
  dst[1] = mt * src1[1] + t * src2[1];
  dst[2] = mt * src1[2] + t * src2[2];
  dst[3] = mt * src1[3] + t * src2[3];
}

#  undef EPS_SATURATION
#  undef EPS_ALPHA

#endif /* __MATH_COLOR_BLEND_INLINE_C__ */