/*

 * Copyright (C) 2001 Havoc Pennington

 * Copyright (C) 2016 Alberts Muktupāvels

 *

 * 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, see <http://www.gnu.org/licenses/>.

 */

#include "config.h"

#include "meta-hsla-private.h"

/**

 * meta_hsla_from_rgba:

 * @hsla: (out): location to store #MetaHSLA color

 * @rgba: #GdkRGBA color

 *

 * Convert RGBA color to HSLA color.

 */

void

meta_hsla_from_rgba (MetaHSLA      *hsla,

                     const GdkRGBA *rgba)

{

  gdouble min;

  gdouble max;

  gdouble red;

  gdouble green;

  gdouble blue;

  gdouble delta;

  g_return_if_fail (hsla != NULL || rgba != NULL);

  red = rgba->red;

  green = rgba->green;

  blue = rgba->blue;

  if (red > green)

    {

      if (red > blue)

        max = red;

      else

        max = blue;

      if (green < blue)

        min = green;

      else

        min = blue;

    }

  else

    {

      if (green > blue)

        max = green;

      else

        max = blue;

      if (red < blue)

        min = red;

      else

        min = blue;

    }

  hsla->hue = 0;

  hsla->saturation = 0;

  hsla->lightness = (max + min) / 2;

  hsla->alpha = rgba->alpha;

  if (max != min)

    {

      if (hsla->lightness <= 0.5)

        hsla->saturation = (max - min) / (max + min);

      else

        hsla->saturation = (max - min) / (2 - max - min);

      delta = max - min;

      if (red == max)

        hsla->hue = (green - blue) / delta;

      else if (green == max)

        hsla->hue = 2 + (blue - red) / delta;

      else if (blue == max)

        hsla->hue = 4 + (red - green) / delta;

      hsla->hue *= 60;

      if (hsla->hue < 0.0)

        hsla->hue += 360;

    }

}

/**

 * meta_hsla_to_rgba:

 * @hsla: #MetaHSLA color

 * @rgba: (out): location to store #GdkRGBA color

 *

 * Convert HSLA color to RGBA color.

 */

void

meta_hsla_to_rgba (const MetaHSLA *hsla,

                   GdkRGBA        *rgba)

{

  gdouble hue;

  gdouble saturation;

  gdouble lightness;

  gdouble m1;

  gdouble m2;

  g_return_if_fail (hsla != NULL || rgba != NULL);

  saturation = hsla->saturation;

  lightness = hsla->lightness;

  if (lightness <= 0.5)

    m2 = lightness * (1 + saturation);

  else

    m2 = lightness + saturation - lightness * saturation;

  m1 = 2 * lightness - m2;

  if (saturation == 0)

    {

      rgba->red = lightness;

      rgba->green = lightness;

      rgba->blue = lightness;

    }

  else

    {

      hue = hsla->hue + 120;

      while (hue > 360)

        hue -= 360;

      while (hue < 0)

        hue += 360;

      if (hue < 60)

        rgba->red = m1 + (m2 - m1) * hue / 60;

      else if (hue < 180)

        rgba->red = m2;

      else if (hue < 240)

        rgba->red = m1 + (m2 - m1) * (240 - hue) / 60;

      else

        rgba->red = m1;

      hue = hsla->hue;

      while (hue > 360)

        hue -= 360;

      while (hue < 0)

        hue += 360;

      if (hue < 60)

        rgba->green = m1 + (m2 - m1) * hue / 60;

      else if (hue < 180)

        rgba->green = m2;

      else if (hue < 240)

        rgba->green = m1 + (m2 - m1) * (240 - hue) / 60;

      else

        rgba->green = m1;

      hue = hsla->hue - 120;

      while (hue > 360)

        hue -= 360;

      while (hue < 0)

        hue += 360;

      if (hue < 60)

        rgba->blue = m1 + (m2 - m1) * hue / 60;

      else if (hue < 180)

        rgba->blue = m2;

      else if (hue < 240)

        rgba->blue = m1 + (m2 - m1) * (240 - hue) / 60;

      else

        rgba->blue = m1;

    }

  rgba->alpha = hsla->alpha;

}

/**

 * meta_hsla_shade:

 * @source: #MetaHSLA color

 * @factor: amount to scale saturation and lightness

 * @destination: (out): location to store #MetaHSLA color

 *

 * Takes a @source color, scales saturation and lightness by @factor and

 * sets @destionation to the resulting color.

 */

void

meta_hsla_shade (const MetaHSLA *source,

                 const gdouble   factor,

                 MetaHSLA       *destination)

{

  g_return_if_fail (source != NULL || destination != NULL);

  destination->hue = source->hue;

  destination->saturation = source->saturation * factor;

  destination->saturation = CLAMP (destination->saturation, 0.0, 1.0);

  destination->lightness = source->lightness * factor;

  destination->lightness = CLAMP (destination->lightness, 0.0, 1.0);

  destination->alpha = source->alpha;

}